Optimal biomarker ranges, with sources

A transparent catalog of the 284 biomarkers Sera supports across 12 health areas, 32 of them auto-calculated from other results rather than entered from a report. Current Sera practitioner targets, with evidence classification and source mapping actively being expanded.

Range set: Sera Production · Version 1.0 · Production · Last reviewed November 9, 2026

See the 17 patterns Sera flags across results

Methodology

Sera ranges are practitioner targets used to support structured blood-work review. They are informed by conventional laboratory reference intervals, published clinical guidance, functional and longevity literature, and feedback from early functional and integrative practitioners.

Evidence strength varies by biomarker. Some values reflect established clinical thresholds or published reference intervals; others are narrower practitioner targets or exploratory ranges. Sera targets should not be treated as universal laboratory reference intervals or as diagnostic thresholds.

Sera does not diagnose, prescribe, or replace professional clinical judgment. Practitioners should interpret results alongside the patient's history, symptoms, examination, laboratory-specific intervals, assay method, and relevant clinical context.

Sera is being developed with feedback from early functional and integrative practitioners. A formal practitioner advisory board is planned.

How Sera reads a result

Optimal
The value falls within Sera's narrower practitioner target.
Sufficient
Outside the Optimal band but within Sera's broader acceptable band.
Out of range
Outside Sera's configured bands. This does not on its own establish disease.
What the evidence labels mean
Established clinical threshold
A band edge that corresponds to a recognised diagnostic, risk or treatment threshold from a major clinical guideline or public-health body.
Published reference interval
A band that primarily reflects a published adult laboratory or population reference interval. It is not necessarily applicable to every assay or laboratory.
Functional / longevity target
A narrower target in common use in functional, integrative, preventive and longevity practice. It is not a universally validated diagnostic range.
Practitioner consensus
A band supported mainly by practitioner experience and repeated use rather than outcome-based evidence.
Exploratory index
A calculated or emerging measure that can be useful for reviewing a pattern but has no universally accepted clinical threshold.
No universal range
Sera deliberately publishes no target. Interpretation depends too heavily on assay, age, population or clinical context for a single band to be honest.
Sera practitioner target — source review pending
The band is in production and the app scores against it, but its evidence has not yet been classified and no source has been mapped to it. Treat it as a Sera practitioner target and read it alongside the issuing laboratory's own interval.
Showing 284 of 284 markers

Heart Health · 26 markers

Cholesterol, lipoproteins, and related cardiovascular risk markers

Total CholesterolEstablished clinical thresholdOne-sidedmg/dL · mmol/L

The total amount of cholesterol in your blood.

UnitOptimalSufficientOut of range
mg/dL120 – 180100 – 200above 200
mmol/L3.1 – 4.72.6 – 5.2above 5.2

Bounded on the high side only — a low result is not treated as out of range. No evidence-based lower bound; a low total cholesterol on lipid-lowering therapy is the treatment working, not a finding.

Interpretation: The acceptable band ends at the conventional 200 mg/dL (the NHS uses 5 mmol/L). The narrower optimal band of 120 to 180 mg/dL is a functional target with limited evidence: no current guideline sets it, and population studies do not show lower mortality below 180. The American Heart Association now scores non-HDL cholesterol in preference to total cholesterol, and that marker is the better one to read. A low result is not flagged.

Sources

  • Cholesterol Levels: What You Need to Know — MedlinePlus, US National Library of Medicine, 2026 · Government / public-health guidanceHealthy adult levels: total cholesterol less than 200 mg/dL, non-HDL less than 130, LDL less than 100, and HDL of 60 or more as best. HDL is low below 40 mg/dL in men and below 50 in women.
  • Cholesterol levels — National Health Service (UK), 2026 · Government / public-health guidanceHealthy adult levels in mmol/L: total cholesterol below 5, non-HDL below 4, and HDL above 1.0 for men or above 1.2 for women.

Last reviewed: November 9, 2026 · Total Cholesterol on its own page

LDL CholesterolEstablished clinical thresholdOne-sidedmg/dL · mmol/L

Low-density lipoprotein, often called bad cholesterol.

UnitOptimalSufficientOut of range
mg/dL0 – 990 – 129above 129
mmol/L0 – 2.60 – 3.3above 3.3

Bounded on the high side only — a low result is not treated as out of range. No evidence-based lower bound; current guidelines set LDL goals as low as 55 mg/dL for people at very high risk.

Interpretation: The optimal band ends at the widely used figure of less than 100 mg/dL. Current guidance sets LDL goals by overall cardiovascular risk, as low as 55 mg/dL, so read the band as a review aid, not a treatment target. A low LDL is not flagged. The acceptable band's upper edge of 129 mg/dL comes from an older category that current guidelines no longer restate.

Sources

Last reviewed: November 9, 2026 · LDL Cholesterol on its own page

HDL CholesterolEstablished clinical thresholdSex-specificmg/dL · mmol/L

High-density lipoprotein, often called good cholesterol.

UnitApplies toOptimalSufficientOut of range
mg/dLFemale60 – 10050 – 120below 50 or above 120
mg/dLMale60 – 10040 – 120below 40 or above 120
mmol/LFemale1.6 – 2.61.3 – 3.1below 1.3 or above 3.1
mmol/LMale1.6 – 2.61 – 3.1below 1 or above 3.1

Interpretation: Low HDL is read by sex: below 40 mg/dL in men and below 50 in women. Where the client's sex is not recorded, the men's figure is used. In mmol/L the women's floor is 1.3, the conversion of 50 mg/dL, where the NHS uses 1.2. The upper edges are not guideline thresholds: they reflect cohort data in which very high HDL was no longer protective.

Sources

  • Cholesterol Levels: What You Need to Know — MedlinePlus, US National Library of Medicine, 2026 · Government / public-health guidanceHealthy adult levels: total cholesterol less than 200 mg/dL, non-HDL less than 130, LDL less than 100, and HDL of 60 or more as best. HDL is low below 40 mg/dL in men and below 50 in women.
  • Cholesterol levels — National Health Service (UK), 2026 · Government / public-health guidanceHealthy adult levels in mmol/L: total cholesterol below 5, non-HDL below 4, and HDL above 1.0 for men or above 1.2 for women.
  • Extreme high high-density lipoprotein cholesterol is paradoxically associated with high mortality in men and women: two prospective cohort studies — Madsen CM, Varbo A, Nordestgaard BG — European Heart Journal, 2017 · Peer-reviewed publicationIn two Danish cohorts, all-cause mortality was lowest at an HDL of 73 mg/dL in men and 93 in women, and higher again from 116 mg/dL in men and 135 in women. The reason Sera's HDL bands have an upper edge at all. One population, observational.

Last reviewed: November 9, 2026 · HDL Cholesterol on its own page

Non-HDL CholesterolEstablished clinical thresholdOne-sidedmg/dL · mmol/L

Your total cholesterol minus HDL, which captures all the cholesterol types that can clog arteries.

UnitOptimalSufficientOut of range
mg/dL0 – 1300 – 160above 160
mmol/L0 – 3.40 – 4.1above 4.1

Bounded on the high side only — a low result is not treated as out of range. No evidence-based lower bound; current guidelines set non-HDL goals as low as 85 mg/dL for people at very high risk.

Interpretation: The optimal band ends at 130 mg/dL and the acceptable band at 160, the first two tiers of the American Heart Association's scoring. The NHS figure of below 4 mmol/L sits just under Sera's 4.1. Guideline goals are lower for people at raised cardiovascular risk, down to 85 mg/dL, so read the band as a review aid, not a treatment target. A low non-HDL is not flagged.

Sources

  • Cholesterol Levels: What You Need to Know — MedlinePlus, US National Library of Medicine, 2026 · Government / public-health guidanceHealthy adult levels: total cholesterol less than 200 mg/dL, non-HDL less than 130, LDL less than 100, and HDL of 60 or more as best. HDL is low below 40 mg/dL in men and below 50 in women.
  • Life's Essential 8: Updating and Enhancing the American Heart Association's Construct of Cardiovascular Health — American Heart Association — Circulation, 2022 · Professional societyScores non-HDL cholesterol below 130 mg/dL as ideal, with 130 to 159 as the next tier and 160 or more below that. The two edges Sera's non-HDL bands end on.
  • Cholesterol levels — National Health Service (UK), 2026 · Government / public-health guidanceHealthy adult levels in mmol/L: total cholesterol below 5, non-HDL below 4, and HDL above 1.0 for men or above 1.2 for women.
  • Guideline on the Management of Dyslipidemia — American College of Cardiology / American Heart Association, 2026 · Clinical guidelineLDL goals set by cardiovascular risk: below 100 mg/dL at borderline or intermediate risk, below 70 at high risk, and below 55 with non-HDL below 85 at very high risk. Replaces the 2018 cholesterol guideline, and is the reason Sera's LDL band is a review aid and not a treatment goal.

Last reviewed: November 9, 2026 · Non-HDL Cholesterol on its own page

Remnant CholesterolFunctional / longevity targetAuto-calculatedmg/dL

The cholesterol carried in VLDL, IDL and other remnant particles — total cholesterol with LDL and HDL taken out.

Auto-calculated

Total cholesterol − LDL − HDL

Calculated when Total Cholesterol and LDL Cholesterol and HDL Cholesterol are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
mg/dL0 – 2424 – 30below 0 or above 30

Interpretation: Captures atherogenic particles LDL cholesterol misses, so a raised remnant with an acceptable LDL is the pattern worth catching. Rises with insulin resistance and with a non-fasting draw. Read the caveat on VLDL cholesterol beside it: where LDL was calculated rather than directly measured, the two markers are the same number by construction and are not independent confirmation of each other.

Sources

  • Remnant cholesterol predicts cardiovascular disease beyond LDL and ApoB: a primary prevention study — Quispe R, Martin SS, Michos ED, et al. — European Heart Journal, 2021 · Peer-reviewed publicationIn 17,532 US adults free of cardiovascular disease, 24 mg/dL was the remnant cholesterol level equivalent to an LDL of 130 mg/dL, and people above it had more cardiovascular events even with LDL below 130. The median was 20 mg/dL. The edge Sera's optimal band ends on.
  • Remnant Cholesterol, Not LDL Cholesterol, Is Associated With Incident Cardiovascular Disease — Castañer O, Pintó X, Subirana I, et al. — Journal of the American College of Cardiology, 2020 · Peer-reviewed publicationIn the PREDIMED cohort, remnant cholesterol of 30 mg/dL or more marked people at higher risk of major cardiovascular events whether or not LDL was on target. The edge Sera's acceptable band ends on. An older, overweight Spanish population at high cardiovascular risk.

Last reviewed: November 9, 2026 · Remnant Cholesterol on its own page

VLDL CholesterolPublished reference intervalAuto-calculatedmg/dL

The cholesterol carried in VLDL particles, estimated from triglycerides.

Auto-calculated

Triglycerides ÷ 5 (mg/dL)

Calculated when Triglycerides is recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
mg/dL2 – 30—below 2 or above 30

No separate Sufficient band is currently defined for this marker.

Interpretation: The triglyceride-over-five approximation, which assumes a typical particle composition and degrades as triglycerides rise — above roughly 400 mg/dL it should not be relied on. Note also that when LDL on the same panel was calculated by the Friedewald equation, this figure and remnant cholesterol are arithmetically identical, because Friedewald derives LDL by subtracting exactly this quantity. They diverge only when LDL was measured directly, and reports rarely say which was done.

Sources

  • VLDL test — MedlinePlus, US National Library of Medicine, 2025 · Government / public-health guidanceGives the normal VLDL cholesterol level as 2 to 30 mg/dL, and notes that the estimate from triglycerides is not accurate above 400 mg/dL.

Last reviewed: November 9, 2026 · VLDL Cholesterol on its own page

TriglyceridesEstablished clinical thresholdmg/dL · mmol/L

A type of fat in your blood that is tied to your diet and metabolism.

UnitOptimalSufficientOut of range
mg/dL0 – 100100 – 150below 0 or above 150
mmol/L0 – 1.131.13 – 1.69below 0 or above 1.69

Interpretation: The upper bound is the conventional 150 mg/dL (1.7 mmol/L) threshold for a fasting sample. A non-fasting draw runs higher, and the equivalent threshold there is 175 mg/dL. The optimal band ending at 100 mg/dL is a functional target: cohort data show risk rising below 150, more clearly in men than in women, but no current guideline sets 100 as a goal.

Sources

Last reviewed: November 9, 2026 · Triglycerides on its own page

Apolipoprotein B (ApoB)Established clinical thresholdOne-sidedmg/dL · g/L

A protein found on LDL, VLDL, and other particles that can clog arteries.

UnitOptimalSufficientOut of range
mg/dL0 – 700 – 100above 100
g/L0 – 0.70 – 1above 1

Bounded on the high side only — a low result is not treated as out of range. No evidence-based lower bound; treatment thresholds run as low as 60 mg/dL for people at very high risk.

Interpretation: The optimal band ends at 70 mg/dL, the National Lipid Association's threshold for people at high cardiovascular risk. Thresholds differ by risk, from 60 to 90 mg/dL, and the association describes them as less well established than those for LDL. The acceptable band's upper edge of 100 mg/dL is wider than the association's 90 and has no source mapped to it yet. A low ApoB is not flagged.

Sources

Last reviewed: November 9, 2026 · ApoB on its own page

Apolipoprotein A1 (ApoA1)Sera practitioner target — source review pendingmg/dL · g/L

The main protein found in HDL particles.

UnitOptimalSufficientOut of range
mg/dL140 – 200120 – 140below 120 or above 200
g/L1.4 – 21.2 – 1.4below 1.2 or above 2

Sources

Source mapping is being expanded. This displayed range is a current Sera practitioner target under review.

Last reviewed: November 9, 2026

Lipoprotein(a) [Lp(a)]Established clinical thresholdOne-sidednmol/L · mg/dL · g/L

A cholesterol-carrying particle whose level is set mostly by your genes.

UnitOptimalSufficientOut of range
nmol/L0 – 750 – 125above 125
mg/dL0 – 300 – 50above 50
g/L0 – 0.30 – 0.5above 0.5

Bounded on the high side only — a low result is not treated as out of range. Risk rises with the level; a low Lp(a) is the favourable direction.

Interpretation: The optimal band ends at 75 nmol/L (30 mg/dL, 0.30 g/L), below which the EAS consensus rules risk out, and the acceptable band at 125 nmol/L (50 mg/dL, 0.50 g/L), above which it rules risk in. The 2026 ACC/AHA guideline uses the same upper figure as a risk-enhancing factor. Lp(a) is largely genetically determined and stable through life, so a single measurement is usually sufficient. g/L and mg/dL are the same mass measurement on different scales (1 g/L = 100 mg/dL). The nmol/L and mass figures are paired cut-offs from different assays, not conversions of one another.

Sources

  • Leistungsverzeichnis Lipoprotein(a) FB-PÄ 6 LPa OE — Universitätsklinikum Ulm, Zentrale Einrichtung Klinische Chemie, 2022 · Laboratory / reference-interval sourceGerman university laboratory directory, revision of 11 March 2022. It states Lp(a) mass in mg/dl with g/l in brackets and links values above about 30 mg/dl (0,3 g/l) with higher atherosclerosis risk, which equals Sera's optimal upper edge of 0.30 g/L. It also cites the EAS recommended range of below 50 mg/dl. The laboratory itself now reports in nmol/l.
  • Lipoprotein(a) in atherosclerotic cardiovascular disease and aortic stenosis: a European Atherosclerosis Society consensus statement — European Atherosclerosis Society — European Heart Journal, 2022 · Professional societySuggests Lp(a) cut-offs to rule risk out below 30 mg/dL (75 nmol/L) and to rule it in above 50 mg/dL (125 nmol/L), with the range between as a grey zone. The two edges Sera's bands end on.
  • Guideline on the Management of Dyslipidemia — American College of Cardiology / American Heart Association, 2026 · Clinical guidelineLDL goals set by cardiovascular risk: below 100 mg/dL at borderline or intermediate risk, below 70 at high risk, and below 55 with non-HDL below 85 at very high risk. Replaces the 2018 cholesterol guideline, and is the reason Sera's LDL band is a review aid and not a treatment goal.

Last reviewed: November 9, 2026 · Lipoprotein(a) on its own page

Uric AcidEstablished clinical thresholdSex-specificmg/dL · μmol/L · mmol/L

A waste product made when the body breaks down substances called purines.

UnitApplies toOptimalSufficientOut of range
mg/dLFemale3.5 – 5.52.5 – 6below 2.5 or above 6
mg/dLMale3.5 – 5.52.5 – 7below 2.5 or above 7
μmol/LFemale208 – 327149 – 357below 149 or above 357
μmol/LMale208 – 327149 – 416below 149 or above 416
mmol/LFemale0.208 – 0.3270.149 – 0.357below 0.149 or above 0.357
mmol/LMale0.208 – 0.3270.149 – 0.416below 0.149 or above 0.416

Interpretation: The acceptable band ends where hyperuricaemia is conventionally defined: above 7 mg/dL in men and above 6 in women. Where the client's sex is not recorded, the men's figure is used. The optimal band ending at 5.5 mg/dL is a functional target, supported by cohort data in which cardiovascular deaths rose from 5.6. The lower edges have no published threshold behind them.

Sources

  • Hyperuricemia — StatPearls — NCBI Bookshelf, US National Library of Medicine, 2023 · Peer-reviewed publicationDefines hyperuricaemia as a serum uric acid usually greater than 6 mg/dL in women and 7 mg/dL in men. The two ceilings of Sera's acceptable band.
  • Identification of the Uric Acid Thresholds Predicting an Increased Total and Cardiovascular Mortality Over 20 Years — Virdis A, Masi S, Casiglia E, et al. — Hypertension, 2020 · Peer-reviewed publicationIn 22,714 Italian adults followed for 20 years, the uric acid level above which deaths rose was 4.7 mg/dL for all causes and 5.6 mg/dL for cardiovascular causes, both well below the level that defines hyperuricaemia. Observational support for an optimal band ending at 5.5.

Last reviewed: November 9, 2026 · Uric Acid on its own page

HomocysteineFunctional / longevity targetOne-sidedμmol/L · nmol/mL

An amino acid that reflects your B-vitamin status and a process called methylation.

UnitOptimalSufficientOut of range
μmol/L0 – 99 – 12above 12
nmol/mL0 – 99 – 12above 12

Bounded on the high side only — a low result is not treated as out of range. No evidence-based lower bound; the published thresholds all concern a raised homocysteine.

Interpretation: Raised homocysteine can reflect low B12, folate or B6 status, or reduced kidney function. It rises with age and is higher in men. The acceptable band ends at 12 μmol/L, just above the 11 an international consensus treats as moderately raised. Laboratories commonly print a wider interval, to about 15. The optimal band ending at 9 is a functional target with no published threshold behind it. A low homocysteine is not flagged.

Sources

  • Homocysteine and Dementia: An International Consensus Statement — Smith AD, Refsum H, Bottiglieri T, et al. — Journal of Alzheimer's Disease, 2018 · Peer-reviewed publicationTreats a plasma total homocysteine above 11 μmol/L as moderately raised and as a modifiable risk factor for cognitive decline in older people. Sera's acceptable band ends just above it, at 12.

Last reviewed: November 9, 2026 · Homocysteine on its own page

LDL Particle Number (LDL-P)Published reference intervalOne-sidedAssay-dependentnmol/L

The number of LDL particles in circulation, measured by NMR, rather than the amount of cholesterol they carry.

UnitOptimalSufficientOut of range
nmol/L0 – 1,0001,000 – 1,600above 1,600

Bounded on the high side only — a low result is not treated as out of range. Risk rises with particle number; a low count is the favourable direction.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Discordance is the reason to measure it: where LDL-P is high and LDL cholesterol is not — the usual pattern in insulin resistance, with small dense particles — the standard panel understates risk. ApoB answers much the same question and is more widely available. NMR and ion-mobility methods do not give interchangeable numbers.

Sources

  • LDL-P (NMR LipoProfile) — reference range — Labcorp, 2026 · Laboratory / reference-interval sourceThe laboratory's tiers for NMR-measured LDL particle number: low below 1000 nmol/L, moderate 1000 to 1299, borderline high 1300 to 1599, high 1600 to 2000, very high above 2000. Sera's optimal band ends where low ends, and its acceptable band where high begins.

Last reviewed: November 9, 2026 · LDL particle number on its own page

LDL Size (NMR)No universal rangeUnbandednm · unbanded

The average diameter of LDL particles, measured by NMR spectroscopy.

No universal Sera range published.

The published cut-offs are percentiles of one laboratory's reference population, not outcome targets. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Sera records LDL size without a band and shows its pattern instead: on NMR, 20.6 nm and above is Pattern A and 20.5 nm and below is Pattern B, the cut-off Labcorp prints. The reference values for the NMR markers are percentiles of one laboratory's reference population rather than outcome targets, the assays are not FDA-cleared, and Labcorp states that LDL size is not associated with heart risk once LDL particle number is taken into account. Gradient-gel electrophoresis uses a cut-off of 25.5 nm on a different scale, and ion mobility reports in angstroms, so only an NMR size belongs here.

Sources

  • NMR LipoProfile w/IR Markers (LAB1048) — Labcorp (performing laboratory; assays by LipoScience), OhioHealth Laboratory Services catalog, 2026 · Laboratory / reference-interval sourceReference values: LDL size above 20.5 nm (20.6 and over Pattern A, 20.5 and under Pattern B), small LDL-P 527 nmol/L or less, HDL-P 30.5 μmol/L or more, most of them the 50th percentile of the reference population. Notes the assays are not FDA-cleared.
  • The effects of fat consumption on low-density lipoprotein particle size in healthy individuals: a narrative review — Froyen E — Lipids in Health and Disease, 2021 · Peer-reviewed publicationRestates the gradient-gel electrophoresis cut-off from Austin and Krauss: a peak LDL diameter above 25.5 nm is Pattern A, below it Pattern B. Shows why a gel size cannot be read on the NMR scale.

Last reviewed: November 9, 2026

Small LDL Particle Number (Small LDL-P)No universal rangeUnbandednmol/L · unbanded

The number of small LDL particles, measured by NMR spectroscopy.

No universal Sera range published.

The published cut-off is the median of one laboratory's reference population, not an outcome target. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Sera records small LDL-P without a band. Labcorp's reference value of 527 nmol/L or less is the median of its reference population, so half of that population sits above it by design, and the assays are not FDA-cleared. Labcorp states that small LDL-P is not associated with heart risk once total LDL particle number is taken into account, so read it with LDL-P.

Sources

  • NMR LipoProfile w/IR Markers (LAB1048) — Labcorp (performing laboratory; assays by LipoScience), OhioHealth Laboratory Services catalog, 2026 · Laboratory / reference-interval sourceReference values: LDL size above 20.5 nm (20.6 and over Pattern A, 20.5 and under Pattern B), small LDL-P 527 nmol/L or less, HDL-P 30.5 μmol/L or more, most of them the 50th percentile of the reference population. Notes the assays are not FDA-cleared.

Last reviewed: November 9, 2026

HDL Particle Number (HDL-P)No universal rangeUnbandedμmol/L · unbanded

The total number of HDL particles, measured by NMR spectroscopy.

No universal Sera range published.

The published cut-off is the median of one laboratory's reference population, and the method has been revised over the years. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Sera records HDL-P without a band. Labcorp's reference value of 30.5 μmol/L or more is the median of its reference population, and the NMR method has been revised over the years, so values from different versions differ. Compare results from the same laboratory.

Sources

  • NMR LipoProfile w/IR Markers (LAB1048) — Labcorp (performing laboratory; assays by LipoScience), OhioHealth Laboratory Services catalog, 2026 · Laboratory / reference-interval sourceReference values: LDL size above 20.5 nm (20.6 and over Pattern A, 20.5 and under Pattern B), small LDL-P 527 nmol/L or less, HDL-P 30.5 μmol/L or more, most of them the 50th percentile of the reference population. Notes the assays are not FDA-cleared.

Last reviewed: November 9, 2026

Oxidized LDL (oxLDL)No universal rangeUnbandedU/L · ng/mL · unbanded

LDL particles that have undergone oxidative modification, the form taken up by macrophages in the arterial wall.

No universal Sera range published.

Assays detect different oxidised epitopes and report on unrelated scales. Read this marker against the interval printed by the issuing laboratory.

Sources

There is no band here to attribute to a source.

Last reviewed: November 9, 2026

Lp-PLA2 ActivityPublished reference intervalOne-sidedAssay-dependentnmol/min/mL

The activity of lipoprotein-associated phospholipase A2, an enzyme produced within atherosclerotic plaque.

UnitOptimalSufficientOut of range
nmol/min/mL0 – 225—above 225

No separate Sufficient band is currently defined for this marker.

Bounded on the high side only — a low result is not treated as out of range. The cleared assay defines only a raised result.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The band ends at 225 nmol/min/mL, the cleared activity assay's own cut-off, and there is no narrower optimal band because nothing published supports one. Vascular-specific in a way hsCRP is not: it rises with plaque inflammation rather than systemic inflammation, which is why the two are not substitutes. Sera bands the activity assay only; the mass assay reports ng/mL on an unrelated scale.

Sources

Last reviewed: November 9, 2026 · Lp-PLA2 on its own page

Lp-PLA2 MassPublished reference intervalOne-sidedAssay-dependentμg/L · ng/mL

The concentration of lipoprotein-associated phospholipase A2 protein, as distinct from the activity of the enzyme.

UnitOptimalSufficientOut of range
μg/L0 – 200200 – 235above 235
ng/mL0 – 200200 – 235above 235

Bounded on the high side only — a low result is not treated as out of range. The published thresholds define only a raised result.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The amount of enzyme present, where Lp-PLA2 activity measures what it is doing. Two quantities on unrelated scales, held as separate markers for that reason — never read a mass result against the activity band. Activity is the better-validated of the two, and is the one to prefer when a laboratory offers both.

Sources

No single publication is cited: this band reflects the conventional adult laboratory interval, which varies between laboratories and assays.

Last reviewed: November 9, 2026

Myeloperoxidase (MPO)Published reference intervalOne-sidedAssay-dependentng/mL · μg/L · pmol/L

An enzyme released by activated neutrophils within the arterial wall, used as a marker of plaque instability.

UnitOptimalSufficientOut of range
ng/mL0 – 350350 – 500above 500
μg/L0 – 350350 – 500above 500
pmol/L0 – 470470 – 540above 540

Bounded on the high side only — a low result is not treated as out of range. The laboratory risk tiers define only a raised result.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Speaks to plaque vulnerability rather than plaque burden, so it can be raised where the lipid panel looks acceptable. Any neutrophil activation lifts it, so an intercurrent infection makes the result uninterpretable — repeat once well. The ng/mL and pmol/L rows come from different assays and do not convert into one another. The pmol/L bands follow the laboratory risk tiers, ending at 470 and 540. The ng/mL and μg/L bands have no published source mapped to them.

Sources

  • Myeloperoxidase (MPO) — reference range — Labcorp, 2026 · Laboratory / reference-interval sourceRisk tiers in pmol/L: low below 470, moderate 470 to 539, high above 539. The edges of Sera's pmol/L bands. The laboratory offers the test for research use, and gives no tiers in ng/mL.

Last reviewed: November 9, 2026 · Myeloperoxidase (MPO) on its own page

NT-proBNPEstablished clinical thresholdOne-sidedpg/mL · ng/L

The inactive fragment released when the heart muscle stretches, and the standard blood marker of cardiac wall stress.

UnitOptimalSufficientOut of range
pg/mL0 – 125125 – 300above 300
ng/L0 – 125125 – 300above 300

Bounded on the high side only — a low result is not treated as out of range. A low NT-proBNP is the reassuring direction; the thresholds define only a raised result.

Interpretation: A rule-out test above all: below roughly 125 pg/mL heart failure is very unlikely in someone not acutely unwell. It rises with age and with reduced kidney function independently of the heart, and — the trap — runs LOWER in obesity, so a normal value at a high BMI is less reassuring than it looks. The optimal band ends at the European Society of Cardiology's 125 pg/mL. The acceptable band's upper edge of 300 is the figure guidelines use to rule out acute heart failure in an emergency setting; NICE refers from 400 in primary care.

Sources

Last reviewed: November 9, 2026 · NT-proBNP on its own page

Triglycerides/HDL RatioExploratory indexAuto-calculatedOne-sided

The ratio of triglycerides to HDL cholesterol, used as a quick stand-in for insulin resistance and heart risk.

Auto-calculated

Triglycerides / HDL

Calculated when Triglycerides and HDL Cholesterol are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio0 – 11 – 2above 2

Bounded on the high side only — a low result is not treated as out of range. A lower ratio is the favourable direction.

Interpretation: Read it as an exploratory index rather than a diagnostic test: no published source supports 1 and 2 as cut-offs, and the figures reported in studies of insulin resistance differ by sex, by population and by whether the ratio is taken in mg/dL or mmol/L. Sera calculates it in mg/dL.

Sources

No source is listed. This is a calculated index with no universally accepted clinical threshold to cite.

Last reviewed: November 9, 2026

AIP (Atherogenic Index of Plasma)Exploratory indexAuto-calculatedindex

The base-10 logarithm of the triglyceride-to-HDL ratio, expressed in molar units.

Auto-calculated

log₁₀(Triglycerides (mmol/L) / HDL (mmol/L))

Calculated when Triglycerides and HDL Cholesterol are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
index-1 – 0.11-1 – 0.21below -1 or above 0.21

Interpretation: A proxy for LDL particle size, which the standard panel does not report: the triglyceride-to-HDL relationship tracks the shift toward small dense LDL. Being a logarithm it is frequently negative, and negative is the good end — a minus sign here is not an error. The edges of 0.11 and 0.21 are the risk tiers proposed by the index's original authors. No current guideline or recent European or North American cohort restates them, so read it as an exploratory index.

Sources

No source is listed. This is a calculated index with no universally accepted clinical threshold to cite.

Last reviewed: November 9, 2026

ApoB/ApoA1 RatioExploratory indexAuto-calculated

ApoB, carried by every particle that can enter the artery wall, against ApoA1, the main protein of HDL.

Auto-calculated

ApoB / ApoA1 (same unit)

Calculated when Apolipoprotein B (ApoB) and Apolipoprotein A1 (ApoA1) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio0 – 0.60.6 – 0.9below 0 or above 0.9

Interpretation: The ratio of ApoB, carried by every particle that can enter the artery wall, to ApoA1, the main protein of HDL. Sera calculates it from the two results after putting them in the same unit. The optimal band ends at 0.6 and the acceptable band at 0.9, the low and medium risk tiers a large Swedish cohort proposed in 2021. The authors call these tentative, and no guideline has adopted a ratio threshold, so read it as an exploratory index alongside ApoB itself, which carries the treatment targets. The cohort found the same pattern in men and women. The often quoted figures of 0.9 for men and 0.8 for women come from older work and are not used. A low ratio is not flagged.

Sources

Last reviewed: November 9, 2026

Total Cholesterol/HDL RatioExploratory indexAuto-calculatedOne-sided

The ratio of total cholesterol to HDL cholesterol, a well-established heart risk marker.

Auto-calculated

Total Cholesterol / HDL

Calculated when Total Cholesterol and HDL Cholesterol are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio0 – 3.50 – 5above 5

Bounded on the high side only — a low result is not treated as out of range. No evidence-based lower bound; a lower ratio is the favourable direction.

Interpretation: Read it as an exploratory index rather than a diagnostic test: the figures of 3.5 and 5 are widely repeated rules of thumb, found in patient references and not in any current guideline. Guidelines have moved to non-HDL cholesterol and ApoB, which answer the same question with thresholds behind them. A low ratio is not flagged.

Sources

No source is listed. This is a calculated index with no universally accepted clinical threshold to cite.

Last reviewed: November 9, 2026

LDL/HDL Ratio (Castelli Risk Index II)Exploratory indexAuto-calculatedOne-sidedratio

LDL cholesterol divided by HDL cholesterol.

Auto-calculated

LDL cholesterol / HDL cholesterol

Calculated when LDL Cholesterol and HDL Cholesterol are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio0 – 22 – 3above 3

Bounded on the high side only — a low result is not treated as out of range. A lower ratio is the favourable direction.

Interpretation: The narrower companion to the total-cholesterol-to-HDL ratio: it drops the VLDL contribution and compares only the two lipoproteins that move in opposite directions. Like every LDL-based measure it is silent on particle number, which is what ApoB and LDL-P address. No published source supports 2 and 3 as cut-offs: the figures reported in cohort studies run from about 2.5 to 3.4 and vary by population, so read it as an exploratory index.

Sources

No source is listed. This is a calculated index with no universally accepted clinical threshold to cite.

Last reviewed: November 9, 2026

Blood Sugar · 16 markers

Glucose, insulin, and long-term blood sugar control

Fasting GlucoseEstablished clinical thresholdmg/dL · mmol/L

Your blood sugar level after not eating, usually overnight.

UnitOptimalSufficientOut of range
mg/dL70 – 8570 – 99below 70 or above 99
mmol/L3.9 – 4.73.9 – 5.5below 3.9 or above 5.5

Interpretation: The acceptable band stops at 99 mg/dL (5.5 mmol/L), immediately below the ADA's impaired-fasting-glucose threshold of 100 mg/dL (5.6 mmol/L). The line is not the same everywhere: NICE in the UK counts 5.5 to 6.9 mmol/L as high risk, and Diabetes Canada does not call fasting glucose impaired until 6.1 mmol/L. The lower edge of 70 mg/dL (3.9 mmol/L) is the usual laboratory lower limit and the conventional definition of low blood sugar. The narrower optimal band ending at 85 mg/dL is a practitioner target, not a guideline figure; no current guideline or recent cohort study sets it.

Sources

  • Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026 — American Diabetes Association Professional Practice Committee — Diabetes Care, 2026 · Clinical guidelinePrediabetes by fasting glucose is 100 to 125 mg/dL (5.6 to 6.9 mmol/L). Sera's sufficient band stops at 99 mg/dL, just below it. Current edition in force.
  • Diabetes Testing — Centers for Disease Control and Prevention, 2024 · Government / public-health guidanceFasting blood sugar: normal is 99 mg/dL or below, prediabetes 100 to 125, diabetes 126 or above. Matches Sera's sufficient upper edge.
  • Glucose — Labcorp, 2026 · Laboratory / reference-interval sourceReference range 70 to 99 mg/dL, the same two numbers as Sera's sufficient band. Page carries no date; opened October 2026.
  • Low Blood Sugar (Hypoglycemia) — Centers for Disease Control and Prevention, 2024 · Government / public-health guidanceBlood sugar below 70 mg/dL is called low blood sugar. The page is written for people with diabetes; it is the conventional figure behind Sera's lower edge of 70.
  • Type 2 diabetes: prevention in people at high risk (PH38): Recommendations — National Institute for Health and Care Excellence, 2017 · Clinical guidelineA fasting plasma glucose of 5.5 to 6.9 mmol/L indicates high risk of type 2 diabetes; below 5.5 is not high risk. Published 2012, last updated September 2017 and still in force. The NICE line sits 0.1 mmol/L lower than the ADA line, so exactly 5.5 mmol/L is high risk under NICE.
  • Definition, Classification and Diagnosis of Diabetes, Prediabetes and Metabolic Syndrome (Chapter 3) — Diabetes Canada Clinical Practice Guidelines Expert Committee (Punthakee Z, Goldenberg R, Katz P), 2018 · Clinical guidelineImpaired fasting glucose is 6.1 to 6.9 mmol/L in Canada, a higher line than the ADA's 5.6. Sera's 5.5 mmol/L is the stricter ADA convention. 2018 is the current full edition.

Last reviewed: November 9, 2026 · Fasting Glucose on its own page

Glucose (Random / Non-Fasting)Published reference intervalmg/dL · mmol/L

Blood glucose drawn without fasting, at any time of day.

UnitOptimalSufficientOut of range
mg/dL70 – 140—below 70 or above 140
mmol/L3.9 – 7.8—below 3.9 or above 7.8

No separate Sufficient band is currently defined for this marker.

Interpretation: The band is Mayo Clinic Laboratories' random glucose interval, 70 to 140 mg/dL, and North Bristol's non-fasting upper limit of 7.8 mmol/L. A German cohort followed for 11.7 years found mortality was not significantly raised below 7.8 mmol/L and doubled from 7.8 to 11.0. A result above 7.8 is not a diagnosis, but usually leads to an HbA1c or a fasting glucose; some NHS laboratories ask for a fasting test above 6.0. The ADA and NICE diagnose diabetes from a random result only at 11.1 mmol/L (200 mg/dL) or more with symptoms. Below 3.9 mmol/L (70 mg/dL) is low blood sugar, although UK laboratories print lower limits of 3.0 to 3.8. There is no optimal band: the value depends on when and what the client last ate. A glucose that the report does not label as random or non-fasting is read as fasting glucose.

Sources

Last reviewed: November 9, 2026 · Random glucose on its own page

Fasting InsulinFunctional / longevity targetAssay-dependentμIU/mL · pmol/L · mIU/L

Your insulin level after not eating, usually overnight.

UnitOptimalSufficientOut of range
μIU/mL3 – 82 – 20below 2 or above 20
pmol/L21 – 5614 – 139below 14 or above 139
mIU/L3 – 82 – 20below 2 or above 20

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No guideline sets a fasting insulin threshold, and assays are not standardised against each other. The acceptable band of 2 to 20 μIU/mL sits between two laboratory intervals and matches neither: Labcorp prints 2.6 to 24.9. The optimal band of 3 to 8 is a functional target with no cohort or society source behind either edge.

Sources

  • Insulin — Labcorp, 2026 · Laboratory / reference-interval sourceReference range for fasting insulin is 2.6 to 24.9 μIU/mL on Labcorp's Roche assay. Sera's sufficient band of 2 to 20 is narrower at the top and wider at the bottom. Page carries no date; opened October 2026.

Last reviewed: November 9, 2026 · Fasting Insulin on its own page

TyG Index (Triglyceride–Glucose Index)Exploratory indexAuto-calculatedindex

A logarithmic combination of fasting triglycerides and fasting glucose, used as a surrogate for insulin resistance.

Auto-calculated

ln(Triglycerides (mg/dL) × Fasting glucose (mg/dL) / 2)

Calculated when Triglycerides and Fasting Glucose are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
index0 – 8.58.5 – 9below 0 or above 9

Interpretation: Does HOMA-IR's job without a fasting insulin, which is why it appears so widely in cohort studies: the two inputs are on every routine panel. Both must come from a genuinely fasting sample; a fed triglyceride inflates it. There is no guideline threshold. Sera's 8.5 and 9.0 are round numbers near cut-offs derived in individual cohorts: 8.46 as a cardiovascular risk enhancer in a Greek general-population cohort, and 8.76 to 9.10 for mortality in US adults with cardiometabolic syndrome. They apply only to the ln(TG × glucose / 2) formula in mg/dL; some papers use a different formula that gives values near 4.9.

Sources

Last reviewed: November 9, 2026

HbA1c (Glycated Hemoglobin)Established clinical thresholdOne-sided% · mmol/mol

Your average blood sugar over the past 2 to 3 months.

UnitOptimalSufficientOut of range
%4.5 – 5.44 – 5.6above 5.6
mmol/mol26 – 3620 – 38above 38

Bounded on the high side only — a low result is not treated as out of range. No established lower limit — a low HbA1c reflects red cell lifespan (haemolysis, recent transfusion, pregnancy) rather than better glycaemic control.

Interpretation: The acceptable band stops at 5.6% (38 mmol/mol), immediately below the ADA's prediabetes threshold of 5.7% (39 mmol/mol). NICE in the UK and Diabetes Canada draw the line higher, at 6.0% (42 mmol/mol). The optimal band ending at 5.4% follows pooled European and US cohort data in which 5.0 to under 5.5% was the lowest-risk group; its lower edge of 4.5% has no published source. A low result is not flagged, but it is not a sign of better control: it usually reflects red cell lifespan, and pooled data show higher mortality below 5.0% in people without diabetes.

Sources

Last reviewed: November 9, 2026 · HbA1c on its own page

eAG (Estimated Average Glucose)No universal rangeAuto-calculatedUnbandedmg/dL · unbanded

HbA1c restated as the average blood glucose it corresponds to, using the ADA's formula.

Auto-calculated

28.7 × HbA1c (%) − 46.7 (ADA)

Calculated when HbA1c (Glycated Hemoglobin) is recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

A restatement of HbA1c in glucose units; HbA1c carries the band. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Calculated from HbA1c by the ADA formula, 28.7 × HbA1c (%) − 46.7. It is HbA1c in glucose units, so it carries no band of its own: HbA1c carries the verdict. An HbA1c entered in mmol/mol is converted to % first by the NGSP/IFCC equation.

Sources

  • eAG/A1C Conversion Calculator — American Diabetes Association, 2026 · Professional societyStates the formula eAG = 28.7 × A1C − 46.7, from the ADAG study (Nathan 2008). The formula Sera uses.

Last reviewed: November 9, 2026

HOMA-IRExploratory indexAuto-calculatedOne-sided

A simple score that estimates how well your body responds to insulin. The name stands for Homeostatic Model Assessment of Insulin Resistance.

Auto-calculated

(Fasting Insulin × Fasting Glucose) / 405

Calculated when Fasting Insulin and Fasting Glucose are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio0.5 – 10.5 – 1.9above 1.9

Bounded on the high side only — a low result is not treated as out of range. No published lower threshold for homa-ir.

Interpretation: HOMA-IR has no guideline threshold and depends on the insulin assay: the same sample has read from 1.3 to 2.1 in different laboratories. The acceptable band ends at 1.9, the upper 95th percentile in healthy Finnish adults and the best cut-off for fatty liver in the same study; a German population study put the upper reference limit higher, at 2.35. The optimal band ending at 1.0 is about the median of healthy adults in that German study (1.09), a functional target and not a risk threshold. A low result is not flagged, because no published threshold defines one.

Sources

Last reviewed: November 9, 2026

QUICKI (Quantitative Insulin Sensitivity Check Index)No universal rangeAuto-calculatedUnbandedUnitless · unbanded

An insulin sensitivity score from fasting insulin and fasting glucose. Lower means less sensitive to insulin.

Auto-calculated

1 / (log₁₀ Fasting Insulin (μIU/mL) + log₁₀ Fasting Glucose (mg/dL))

Calculated when Fasting Insulin and Fasting Glucose are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

Insulin assays are not standardised, so no cut-off holds across laboratories. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Calculated as 1 / (log fasting insulin + log fasting glucose), the formula in the NIH Endotext chapter. It is a transform of the same two numbers HOMA-IR uses and adds no new information. The same chapter states that no universal cut-off is possible, because insulin assays are not standardised, so Sera shows it without a band.

Sources

  • Assessing Insulin Sensitivity and Resistance in Humans — Muniyappa R, Madan R, Varghese RT — Endotext, 2024 · Professional societyGives QUICKI = 1 / (log fasting insulin in μU/mL + log fasting glucose in mg/dL), and states that no universal cut-off is possible because insulin assays are not standardised.

Last reviewed: November 9, 2026

Glucose (2h Post-Meal)Functional / longevity targetmg/dL · mmol/L

Blood sugar measured about two hours after eating a normal meal.

UnitOptimalSufficientOut of range
mg/dL70 – 12070 – 140below 70 or above 140
mmol/L3.9 – 6.73.9 – 7.8below 3.9 or above 7.8

Interpretation: No guideline sets a 2-hour post-meal range for adults without diabetes. The 140 mg/dL (7.8 mmol/L) edge is borrowed from the 2-hour value of the glucose tolerance test, which uses a standard glucose drink, not a meal; sensor data from healthy adults agree with it in practice, with glucose above 140 for about 2% of the day. The optimal edge of 120 mg/dL (6.7 mmol/L) is a functional target with no published source. A result below 70 mg/dL (3.9 mmol/L) is flagged as low, as it is for fasting glucose: low blood sugar two hours after eating is a finding in its own right.

Sources

  • 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026 — American Diabetes Association Professional Practice Committee — Diabetes Care, 2026 · Clinical guidelineTwo hours after a 75 g glucose drink, 140 to 199 mg/dL (7.8 to 11.0 mmol/L) is impaired glucose tolerance. Sera applies the same 140 line to a meal, which the guideline does not do. Current edition in force.
  • Diabetes Tests & Diagnosis — National Institute of Diabetes and Digestive and Kidney Diseases (NIH), 2022 · Government / public-health guidanceTwo hours after the glucose drink, normal is 139 mg/dL or below and prediabetes is 140 to 199. Supports ending the band at 139, not 140.
  • Continuous Glucose Monitoring Profiles in Healthy Nondiabetic Participants: A Multicenter Prospective Study — Shah VN, DuBose SN, Li Z, et al. — The Journal of Clinical Endocrinology & Metabolism, 2019 · Peer-reviewed publication153 healthy, non-obese US participants aged 7 to 80 wore a blinded glucose sensor: glucose was between 70 and 140 mg/dL for a median 96% of the time and above 140 for 2.1% (about 30 minutes a day). Healthy people seldom exceed 140 at any time, meals included. Says nothing about 120.
  • Low Blood Sugar (Hypoglycemia) — Centers for Disease Control and Prevention, 2024 · Government / public-health guidanceBlood sugar below 70 mg/dL (3.9 mmol/L) is called low blood sugar, whenever it is measured. The page is written for people with diabetes; it is the conventional figure behind the lower edge of this band.

Last reviewed: November 9, 2026 · 2-hour post-meal glucose on its own page

C-PeptideSera practitioner target — source review pendingAssay-dependentng/mL · nmol/L · μg/L · pmol/L

A fragment released in equal amounts to insulin when your pancreas makes it, so it shows how much insulin your own body is producing.

UnitOptimalSufficientOut of range
ng/mL0.8 – 3.9—below 0.8 or above 3.9
nmol/L0.265 – 1.29—below 0.265 or above 1.29
μg/L0.8 – 3.9—below 0.8 or above 3.9
pmol/L265 – 1,290—below 265 or above 1,290

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Laboratories disagree, and Sera's band of 0.8 to 3.9 ng/mL matches none of them: Mayo and Labcorp give 1.1 to 4.4 ng/mL fasting, and a UK NHS laboratory gives 190 to 990 pmol/L, about half that at the top. Read the result against the range on the report, and only for a fasting sample.

Sources

  • CPR - Overview: C-Peptide, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceFasting reference interval 1.1 to 4.4 ng/mL by electrochemiluminescence immunoassay; convert with ng/mL x 331 = pmol/L. The page is undated (current test catalogue, opened October 2026). It also states more than 20% cross-reactivity with proinsulin. Neither edge matches Sera's 0.8 or 3.9.
  • C-Peptide (test 010108) — Labcorp, 2026 · Laboratory / reference-interval sourceReference interval 1.1 to 4.4 ng/mL for fasting patients, by electrochemiluminescence immunoassay on the Roche cobas. Undated test directory page, opened October 2026. Same interval as Mayo.
  • C-Peptide (serum) — Royal Liverpool and Broadgreen University Hospitals NHS Trust pathology, 2026 · Laboratory / reference-interval sourceFasting reference range 190 to 990 pmol/L, sample to be taken with a blood glucose. The page carries no date (opened October 2026). It is lower at both ends than the US interval, which is the evidence that the band is assay-dependent.
  • C-peptide — Oxford University Hospitals NHS Foundation Trust, Clinical Biochemistry, 2026 · Laboratory / reference-interval sourceGives decision thresholds rather than a reference range: fasting C-peptide below 80 pmol/L suggests absolute insulin deficiency. Says C-peptide increases and is uninterpretable in renal impairment. Undated page, opened October 2026.

Last reviewed: November 9, 2026

Glucose (2h OGTT)Established clinical thresholdmg/dL · mmol/L

The 2-hour blood sugar from a formal oral glucose tolerance test, where you drink a standard 75g glucose solution after fasting.

UnitOptimalSufficientOut of range
mg/dL70 – 12070 – 140below 70 or above 140
mmol/L3.9 – 6.73.9 – 7.8below 3.9 or above 7.8

Interpretation: Bands follow the standardised 75 g OGTT thresholds in the ADA Standards of Care 2026: impaired glucose tolerance from 7.8 mmol/L (140 mg/dL), diabetes from 11.1 mmol/L (200 mg/dL). Diagnostic because the glucose load is standardised, unlike a post-meal sample. The optimal band ending at 6.7 mmol/L (120 mg/dL) is a functional target: no guideline defines a tighter 2-hour target below 7.8, although risk rises gradually through the normal range rather than starting at the threshold. A 2-hour result below 3.9 mmol/L (70 mg/dL) is flagged as low, as it is for fasting glucose.

Sources

  • Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026 — American Diabetes Association Professional Practice Committee — Diabetes Care, 2026 · Clinical guidelineTable 2.2 defines impaired glucose tolerance as a 2-hour value of 140 to 199 mg/dL (7.8 to 11.0 mmol/L) during a 75 g OGTT; Table 2.1 defines diabetes as 200 mg/dL (11.1 mmol/L) or more. Sera's acceptable band stops just below 140 mg/dL.
  • Low Blood Sugar (Hypoglycemia) — Centers for Disease Control and Prevention, 2024 · Government / public-health guidanceBlood sugar below 70 mg/dL (3.9 mmol/L) is called low blood sugar, whenever it is measured. The page is written for people with diabetes; it is the conventional figure behind the lower edge of this band.

Last reviewed: November 9, 2026 · 2-hour OGTT glucose on its own page

FructosaminePublished reference intervalμmol/L · mmol/L

Glycated serum proteins, reflecting average glucose over the previous two to three weeks.

UnitOptimalSufficientOut of range
μmol/L200 – 250250 – 285below 200 or above 285
mmol/L0.2 – 0.250.25 – 0.285below 0.2 or above 0.285

Interpretation: A two-to-three-week window rather than HbA1c's three months, which makes it the better measure where red cell lifespan is abnormal — haemolysis, recent transfusion, pregnancy, chronic kidney disease — and for judging a change made a few weeks ago. It falls with low albumin for reasons unconnected to glucose, so check protein status before reading a low value as improvement. The acceptable band of 200 to 285 μmol/L is the Mayo Clinic Laboratories reference interval, and UK laboratories agree on the upper edge. The optimal upper edge of 250 has no source: in healthy US adults the upper reference limit was 258.

Sources

  • FRUCT - Overview: Fructosamine, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference interval 200 to 285 μmol/L (colorimetric method), reflecting glycaemic control over the previous 1 to 3 weeks. Matches both outer edges of Sera's band. Undated test catalogue page, opened October 2026.
  • Fructosamine — North Bristol NHS Trust, Severn Pathology, 2026 · Laboratory / reference-interval sourceSerum reference range 205 to 285 μmol/L; described as occasionally useful where HbA1c is unreliable, for example reduced red cell survival. Supports the upper edge of 285; the lower edge is 5 above Sera's. Undated page, opened October 2026.
  • Fructosamine — University Hospitals Birmingham NHS Foundation Trust, Clinical Biochemistry, 2026 · Laboratory / reference-interval sourceAdult reference range 205 to 285 μmol/L, sourced to Abbott Diagnostics. States fructosamine should not be used in patients with proteinuria because it is lowered by urinary albumin loss. Undated page, opened October 2026.
  • Fructosamine — University of Michigan MLabs, 2026 · Laboratory / reference-interval sourceReference range 185 to 285 μmol/L. Same upper edge as Sera; the lower limit is 15 below Sera's 200, so results of 185 to 199 are normal at this laboratory. Undated page, opened October 2026.
  • Establishment of Community-Based Reference Intervals for Fructosamine, Glycated Albumin, and 1,5-Anhydroglucitol. — Selvin E, Warren B, He X, Sacks DB, Saenger AK — Clinical Chemistry, 2018 · Peer-reviewed publicationIn 1,799 healthy US adults (ARIC study) the 2.5th and 97.5th percentiles for fructosamine were 194.8 and 258.0 μmol/L, and the value equivalent to an HbA1c of 6.5% was 270.2 μmol/L. Supports an upper limit of healthy near 258, not Sera's 250, and shows 285 lies above the diabetes-equivalent value.

Last reviewed: November 9, 2026 · Fructosamine on its own page

1,5-Anhydroglucitol (1,5-AG)Published reference intervalSex-specificOne-sidedμg/mL

A sugar from food that the kidneys normally reabsorb. When glucose spills into the urine, it pushes 1,5-AG out with it, so the blood level falls.

UnitApplies toOptimalSufficientOut of range
μg/mLFemale6.8 – 29.3—below 6.8
μg/mLMale10.7 – 32—below 10.7

No separate Sufficient band is currently defined for this marker.

Bounded on the low side only — a high result is not treated as out of range. A low result is the finding, from glucose spilling into the urine; a high result has no clinical meaning.

Interpretation: The bands are Labcorp's adult intervals: 10.7 to 32.0 μg/mL for men and 6.8 to 29.3 for women. An independent US community study gives 8.4 to 28.7 for both sexes together. The low edge is the one that matters: 1,5-AG falls when glucose repeatedly passes about 180 mg/dL (10 mmol/L), so a low result signals glucose spikes over the past one to two weeks, and a high result is not flagged. It reads falsely low with SGLT2 inhibitors, in pregnancy and in advanced kidney or liver disease. No UK or European laboratory offering the test was found, and no source supports a narrower optimal range.

Sources

Last reviewed: November 9, 2026 · 1,5-AG on its own page

ProinsulinNo universal rangeUnbandedpmol/L · unbanded

The precursor molecule the beta cell cleaves to make insulin, released intact when that processing is under strain.

No universal Sera range published.

Cross-reactivity with insulin and its split products differs by assay, so results are not comparable between laboratories. Read this marker against the interval printed by the issuing laboratory.

Sources

  • PINS - Overview: Proinsulin, Plasma — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceFasting reference interval 3.6 to 22 pmol/L on an unpublished Mayo method; for insulinoma during hypoglycaemia, sensitivity is about 75% at 22 pmol/L and above 95% at a 5 pmol/L cut-off. A single-laboratory interval for a specific diagnostic use. Undated test catalogue page, opened October 2026.

Last reviewed: November 9, 2026

AdiponectinNo universal rangeUnbandedμg/mL · mg/L · unbanded

A hormone secreted by adipose tissue that increases insulin sensitivity, and one of the few markers that falls as adiposity rises.

No universal Sera range published.

Intervals depend on which fraction is measured, total or high-molecular-weight, and are not transferable between assays. Read this marker against the interval printed by the issuing laboratory.

Sources

  • Adiponectin, Quantitative Serum/Plasma (test 3017195) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceAdults over 19 years: men 2.00 to 13.9 μg/mL, women 4.00 to 19.4 μg/mL, by a laboratory-developed ELISA. Sex-specific and different from Labcorp's age-based intervals. Undated test directory page, opened October 2026.
  • Adiponectin (test 004650) — Labcorp, 2026 · Laboratory / reference-interval sourceAge-banded intervals with no sex split, by a laboratory-developed ELISA not cleared by the FDA: 2.5 to 12.3 at ages 20 to 29, rising to 3.0 to 21.1 at 60 to 100. The page's table header prints the unit as 'mL'; the result unit listed elsewhere on the page is ug/mL. Undated page, opened October 2026.
  • A method comparison of total and HMW adiponectin: HMW/total adiponectin ratio varies versus total adiponectin, independent of clinical condition. — van Andel M, Drent ML, van Herwaarden AE, Ackermans MT, Heijboer AC — Clinica Chimica Acta, 2017 · Peer-reviewed publicationDutch method comparison: the high-molecular-weight to total adiponectin ratio changes with the total concentration, so one fraction cannot be read against the other's interval. Supports Sera's stated reason for publishing no band. The quote carries no threshold number because the paper sets none.

Last reviewed: November 9, 2026

Free Fatty Acids (NEFA)No universal rangeUnbandedmmol/L · mEq/L · unbanded

Non-esterified fatty acids circulating in plasma, released as adipose tissue breaks down stored fat.

No universal Sera range published.

Levels rise in the tube after collection unless the sample is separated promptly, so no interval survives ordinary handling variation. Read this marker against the interval printed by the issuing laboratory.

Sources

  • NEFA - Overview: Free Fatty Acids, Total, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults 18 and over: 0.00 to 0.72 mmol/L by enzymatic colorimetric method, after a required 12 hour fast, with serum centrifuged within 45 minutes and frozen immediately. Patients on therapeutic heparin are unsuitable. Undated test catalogue page, opened October 2026.
  • Fatty Acids, Free — University of Michigan MLabs, 2026 · Laboratory / reference-interval sourceReference range below 0.73 mmol/L, from a fasting patient (12 to 14 hours), with the sample centrifuged within 45 minutes and frozen. Shows the handling requirement behind Sera's reason for publishing no band. Undated page, opened October 2026.

Last reviewed: November 9, 2026

Liver & Pancreas Health · 30 markers

Liver enzymes, bilirubin, and synthetic-function markers

ALT (Alanine Aminotransferase)Published reference intervalU/L · IU/L

An enzyme that lives mainly inside liver cells.

UnitOptimalSufficientOut of range
U/L7 – 207 – 45below 7 or above 45
IU/L7 – 207 – 45below 7 or above 45

Interpretation: The acceptable band of 7 to 45 U/L is a laboratory reference interval: it is Mayo Clinic Laboratories' interval for women, and Mayo's limit for men is higher at 55. Other reputable sources stop lower (MedlinePlus 36, NHS 40), so read a result near the top against the range on the report. The optimal band ending at 20 U/L is a stricter functional target with no published threshold behind it: the American College of Gastroenterology puts the healthy-normal limit at 33 U/L in men and 25 in women, and says levels above that should be assessed. A low ALT has no established clinical meaning.

Sources

  • ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries — Kwo PY, Cohen SM, Lim JK — The American Journal of Gastroenterology, 2017 · Clinical guidelineCurrent edition in force. A true healthy normal ALT is up to 29 to 33 IU/L in men and 19 to 25 IU/L in women; higher levels should be assessed. Supports the proposed optimal ceilings of 33 (men) and 25 (women).
  • ALT - Overview: Alanine Aminotransferase (ALT) (GPT), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference interval 7 to 55 U/L in men and 7 to 45 U/L in women. Matches Sera's lower edge of 7 and, for women, the sufficient upper edge of 45.
  • Alanine transaminase (ALT) blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal range 4 to 36 U/L. A tighter upper limit than Sera's 45 and a lower floor than Sera's 7.
  • Assessing liver function and interpreting liver blood tests — NHS Specialist Pharmacy Service, 2024 · Government / public-health guidanceNormal ALT and AST are 0 to 40 IU/L. UK figure, close to Sera's ALT upper edge of 45 and with no lower limit.

Last reviewed: November 9, 2026 · ALT on its own page

AST (Aspartate Aminotransferase)Published reference intervalU/L · IU/L

An enzyme found in the liver and also in muscle.

UnitOptimalSufficientOut of range
U/L8 – 208 – 40below 8 or above 40
IU/L8 – 208 – 40below 8 or above 40

Interpretation: The acceptable band is a laboratory reference interval: the NHS gives a normal AST of up to 40 IU/L, and Mayo Clinic Laboratories and MedlinePlus put the lower limit at 8. Mayo's upper limits are slightly higher (48 in men, 43 in women), so read a result just above 40 against the range on the report. The optimal ceiling of 20 U/L is a functional target; no guideline or cohort source was found for it. AST also comes from muscle, so hard exercise or muscle injury can raise it without liver disease. A low AST has no established clinical meaning.

Sources

Last reviewed: November 9, 2026 · AST on its own page

AST:ALT Ratio (De Ritis)No universal rangeAuto-calculatedUnbandedUnitless · unbanded

The ratio between two liver enzymes, AST and ALT.

Auto-calculated

AST / ALT

Calculated when AST (Aspartate Aminotransferase) and ALT (Alanine Aminotransferase) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

No meaningful reference interval exists for the ratio itself. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Read as a pattern alongside the individual enzymes rather than against a band. No laboratory publishes a reference interval for the ratio. The British Society of Gastroenterology guideline notes that a ratio above 1 points towards advanced fibrosis or cirrhosis, and that this holds even when both enzymes are within their reference intervals.

Sources

  • Guidelines on the management of abnormal liver blood tests — Newsome PN, Cramb R, Davison SM, et al. — Gut (British Society of Gastroenterology), 2018 · Clinical guidelineAn AST:ALT ratio above 1 indicates advanced fibrosis or cirrhosis, and the ratio remains useful when both enzymes are within the reference interval. Sera publishes no band; this supports the note only.

Last reviewed: November 9, 2026

FIB-4 IndexEstablished clinical thresholdAuto-calculatedindex

A non-invasive estimate of liver fibrosis risk built from age, the two transaminases and the platelet count.

Auto-calculated

(Age × AST) / (Platelets (×10⁹/L) × √ALT)

Calculated when AST (Aspartate Aminotransferase) and ALT (Alanine Aminotransferase) and Platelets (Thrombocytes) are recorded in the same blood test, after normalizing the inputs to the units the formula expects. Also needs the client’s age from their record — without it this marker is not calculated at all.

UnitOptimalSufficientOut of range
index0 – 1.31.3 – 2.67below 0 or above 2.67

Interpretation: The first-line fibrosis screen in fatty liver disease, and the band edges are the published decision thresholds rather than a distribution: below 1.3 the AASLD and EASL-EASD-EASO guidelines treat advanced fibrosis as unlikely, 1.3 to 2.67 is the intermediate range that calls for a second test such as elastography, and above 2.67 the AASLD guidance advises considering specialist referral. Both guidelines use a lower cut-off of 2.0 instead of 1.3 in people over 65, and AASLD says accuracy is low under 35; Sera's band does not adjust for age. It should not be used in acute illness. Requires a date of birth on the client — without one it is not computed at all.

Sources

Last reviewed: November 9, 2026 · FIB-4 Index on its own page

ALP (Alkaline Phosphatase)Published reference intervalSex-specificU/L · IU/L

An enzyme found in the liver, bones, kidneys, and gut. High levels can point to liver or bone problems, while low levels can hint at nutrient shortfalls.

UnitApplies toOptimalSufficientOut of range
U/LMale45 – 9030 – 129below 30 or above 129
U/LFemale35 – 8030 – 105below 30 or above 105
IU/LMale45 – 9030 – 129below 30 or above 129
IU/LFemale35 – 8030 – 105below 30 or above 105

Interpretation: The acceptable bands are laboratory reference intervals. The upper edges follow Mayo Clinic Laboratories and MedlinePlus (129 U/L in men, about 104 in women); the lower edge of 30 follows the UK range of 30 to 130 used by NHS laboratories, which is not split by sex. Mayo's own lower limits are higher, 40 in men and 35 in women. The optimal bands are functional targets; no published source was found for them. ALP comes from bone as well as liver, so it runs higher in adolescents, in pregnancy and after a fracture, and a raised result with a normal GGT points to bone rather than liver. A persistently low ALP is worth noting because it can reflect hypophosphatasia or zinc deficiency.

Sources

  • ALP - Overview: Alkaline Phosphatase, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference interval 40 to 129 U/L in men (19 and over) and 35 to 104 U/L in women (17 and over). Supports the women's upper edge of 105 (close) and a men's upper edge of 129.
  • ALP - blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal range 40 to 129 IU/L. Supports an upper edge of 129.
  • Liver Function Test Reference Ranges in Normal Pregnancy — Scarborough, Hull and York Pathology Service, York and Scarborough Teaching Hospitals NHS Foundation Trust, 2022 · Laboratory / reference-interval sourceNon-pregnant adult ranges given for comparison: ALP 30 to 130 U/L, ALT 0 to 34, AST 0 to 31, GGT 0 to 38, total bilirubin below 21 µmol/L. Supports a lower edge of 30.

Last reviewed: November 9, 2026 · ALP on its own page

GGT (Gamma-Glutamyl Transferase)Functional / longevity targetU/L · IU/L

A liver enzyme that is sensitive to problems with the bile ducts.

UnitOptimalSufficientOut of range
U/L5 – 205 – 55below 5 or above 55
IU/L5 – 205 – 55below 5 or above 55

Interpretation: The acceptable band's upper edge of 55 U/L matches no published interval: Mayo Clinic Laboratories gives 61 for men and 36 for women, MedlinePlus 40 for adults, and NHS sources 38 to 50. A woman between 37 and 55 is therefore above some laboratories' limit while reading Sufficient here. The optimal ceiling of 20 is a functional target; cohort data support lower being better without fixing the number.

Sources

Last reviewed: November 9, 2026 · GGT on its own page

AmylasePublished reference intervalAssay-dependentU/L · IU/L

A starch-digesting enzyme produced by the pancreas and the salivary glands.

UnitOptimalSufficientOut of range
U/L30 – 10025 – 125below 25 or above 125
IU/L30 – 10025 – 125below 25 or above 125

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Not specific to the pancreas — salivary disease, a perforated ulcer and ordinary renal impairment all raise it — and it clears within days, so a late sample can be normal in genuine pancreatitis. Lipase is the better single test; this one earns its place by being ordered alongside. Both bands are laboratory reference intervals, not outcome targets: the inner band is Mayo Clinic Laboratories' adult interval (28 to 100 U/L) and the outer band of 25 to 125 is one used by US hospital laboratories for adults under 70. Intervals differ between methods (MedlinePlus quotes 40 to 140), so a result near an edge has to be read against the interval on the report.

Sources

  • AMS - Overview: Amylase, Total, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference interval 28 to 100 U/L. Matches Sera's optimal upper edge of 100; the lower limit of 28 is close to Sera's 30.
  • AMYLASE (Test Code LAB4012) — Kootenai Health Laboratory test catalog, 2026 · Laboratory / reference-interval sourceReference range 25 to 125 U/L for ages 19 to under 70 (20 to 160 from age 70). Matches Sera's sufficient band exactly.
  • Amylase - blood — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal range 40 to 140 U/L, higher than Sera's band at both ends; shows the spread between methods.

Last reviewed: November 9, 2026 · Amylase on its own page

LipasePublished reference intervalOne-sidedAssay-dependentU/L · IU/L

A fat-digesting enzyme produced almost entirely by the pancreas.

UnitOptimalSufficientOut of range
U/L10 – 608 – 80above 80
IU/L10 – 608 – 80above 80

Bounded on the high side only — a low result is not treated as out of range. No agreed lower limit: alberta's harmonised interval and medlineplus have none, and mayo's is 13 rather than 8 or 10.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: More specific than amylase and raised for longer, so it survives a delayed presentation. Reference intervals differ several-fold between methods, which is why a mildly raised result has to be read against the interval on the report: Mayo Clinic Laboratories uses 13 to 60 U/L, Alberta's harmonised adult interval is below 80, and MedlinePlus quotes up to 160. Sera's bands end at the Mayo and Alberta upper limits. A low result is not flagged, because Alberta's interval and MedlinePlus set no lower limit and no source gives a low lipase a threshold.

Sources

  • LPS - Overview: Lipase, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference interval 13 to 60 U/L. Matches Sera's optimal upper edge of 60; its lower limit is 13, not Sera's 10 or 8.
  • Lipase and lactate dehydrogenase (LD) updated reference intervals and implementation of lipase correction factor — Alberta Precision Laboratories (Laboratory Bulletin, 19 September 2022), 2022 · Laboratory / reference-interval sourceProvince-wide harmonised adult lipase interval is below 80 U/L with no lower limit; results differed so much between instruments that a correction factor was introduced. Matches Sera's sufficient upper edge of 80.
  • Lipase test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal results are 0 to 160 U/L in general: twice Sera's upper edge and with no lower limit, which shows the method spread.

Last reviewed: November 9, 2026 · Lipase on its own page

LDH (Lactate Dehydrogenase)No universal rangeUnbandedAssay-dependentU/L · IU/L · unbanded

An enzyme found in almost every cell in the body, released when cells break down. It sits in the liver panel by convention rather than because it is a liver test.

No universal Sera range published.

Published intervals differ by assay method and do not overlap. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No band is published. Laboratories using the current lactate-to-pyruvate method report adult intervals that agree closely: 122 to 222 U/L (Mayo Clinic Laboratories), 125 to 220 (MedlinePlus), 120 to 250 (Alberta) and 135 to 225 (a UK hospital laboratory). Results from the older pyruvate-to-lactate method run much higher; one UK laboratory recorded a fall of about 45 percent when it changed method. Because the method is not printed on most reports, read the result against the interval on the report. LDH is released by many tissues, and a haemolysed sample raises it falsely.

Sources

Last reviewed: November 9, 2026

CK (Creatine Kinase)Published reference intervalSex-specificU/L · μkat/L

An enzyme that muscle cells release into the blood when they are worked hard or damaged.

UnitApplies toOptimalSufficientOut of range
U/LFemale0 – 200—below 0 or above 200
U/LMale0 – 320—below 0 or above 320
μkat/LFemale0 – 3.33—below 0 or above 3.33
μkat/LMale0 – 5.33—below 0 or above 5.33

No separate Sufficient band is currently defined for this marker.

Interpretation: The band ends at 200 U/L in women and 320 U/L in men, the adult interval an NHS laboratory prints, and within the upper limits a 2025 European systematic review found for people of European and Asian ancestry. Where the client's sex is not recorded, the men's figure is used. Laboratories disagree widely, from 170 U/L for men in a US reference table to about 400 U/L in the Nordic interval, so the laboratory's own range takes precedence. A raised CK usually means muscle damage. Hard or unaccustomed exercise in the previous days, a muscle injury, an intramuscular injection and statins all raise it, so ask about each before reading a high result. People of African ancestry run much higher without disease, with upper limits of 520 to 810 U/L in Black men. A low CK is not flagged: it mostly reflects low muscle mass and has no published threshold. 1 μkat/L equals 60 U/L.

Sources

  • Creatine Kinase (CK) — Exeter Clinical Laboratory International, Royal Devon University Healthcare NHS Foundation Trust, 2019 · Laboratory / reference-interval sourceNHS laboratory adult interval for serum CK: men 40 to 320 U/L, women 25 to 200 U/L. The page adds that the range is broad and skewed to the top, that CK falls with age, and that Black men run highest. Revised March 2019.
  • Kreatinkinas, P- — Karolinska Universitetslaboratoriet (Karolinska University Hospital, Stockholm), 2025 · Laboratory / reference-interval sourceSwedish adult interval in microkat/L, taken from the Nordic NORIP reference project: women 0.6 to 3.5, men 18 to 49 years 0.8 to 6.7, men 50 and over 0.7 to 4.7 (about 210, 400 and 280 U/L at the top). Revised August 2025. Confirms the μkat/L reporting unit and that the men's upper limit is higher.
  • Creatine kinase (CK) — University Hospitals Birmingham NHS Foundation Trust, Pathology, 2026 · Laboratory / reference-interval sourceAdult interval on the Abbott assay: women 29 to 168 U/L, men 30 to 200 U/L. States that CK is higher in men and in Black populations, and that exercise, muscle trauma and statins raise it. Updated August 2026. A tighter upper limit than Sera's proposal, cited to show how far laboratories differ.
  • ABIM Laboratory Test Reference Ranges, January 2026 — American Board of Internal Medicine, 2026 · Laboratory / reference-interval sourceUS reference table used for internal medicine certification: total CK women 30 to 135 U/L, men 55 to 170 U/L. The tightest of the intervals found, cited as the North American comparison.
  • What Are the Normal Serum Creatine Kinase Values for Skeletal Muscle? A Worldwide Systematic Review — Aleksovska K, Kyriakides T, Angelini C, et al. (European neuromuscular authors) — European Journal of Neurology, 2025 · Peer-reviewed publicationSystematic review of CK reference studies: upper limits of 227 to 440 U/L in Caucasian and Asian men and 520 to 810 U/L in Black men, and 135 to 248 U/L in women (up to 354 in Black women). The proposed edges of 320 and 200 sit inside the non-Black ranges.
  • Creatine kinase in the U.S. population: Impact of demographics, comorbidities, and body composition on the normal range — George MD, McGill NK, Baker JF — Medicine (Baltimore), 2016 · Peer-reviewed publicationNHANES analysis: the 97.5th percentile of CK was 382 U/L in white men and 1001 in Black men, 295 in white women and 487 in Black women. Supports the note that people of African ancestry run well above a standard upper limit.
  • Creatine Kinase — MedlinePlus, US National Library of Medicine, 2023 · Government / public-health guidanceStates that a raised CK usually means muscle damage, from disease, injury, certain medicines such as statins, or recent intense exercise, and that normal levels depend on age, sex and race. Gives no numbers.

Last reviewed: November 9, 2026 · Creatine kinase on its own page

Bilirubin (Total)Published reference intervalOne-sidedmg/dL · μmol/L

A yellow pigment made when old red blood cells break down. The liver processes it and removes it in bile, so it reflects both liver function and red blood cell turnover.

UnitOptimalSufficientOut of range
mg/dL0.3 – 10.2 – 1.2above 1.2
μmol/L5 – 173 – 21above 21

Bounded on the high side only — a low result is not treated as out of range. Most laboratory intervals have no lower limit (mayo 0.0, york nhs none) and no source gives a low bilirubin a clinical meaning.

Interpretation: The acceptable band ends at the adult upper reference limit used by Mayo Clinic Laboratories, MedlinePlus and NHS laboratories: 1.2 mg/dL, or 21 µmol/L. A low result is not flagged, because most laboratories set no lower limit and no source gives a low bilirubin a clinical meaning. The optimal band of 0.3 to 1.0 mg/dL is a functional target with no published threshold behind its upper edge. An isolated raised unconjugated bilirubin with a normal blood count and normal liver enzymes commonly reflects Gilbert's syndrome, a benign inherited variant; the British Society of Gastroenterology guideline says such people should be fully reassured.

Sources

  • BILI3 - Overview: Bilirubin, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult total bilirubin 0.0 to 1.2 mg/dL. Matches Sera's sufficient upper edge of 1.2; the interval has no lower limit above zero.
  • Bilirubin blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal total bilirubin 0.1 to 1.2 mg/dL (1.71 to 20.5 µmol/L). Matches Sera's upper edge in both units; its floor is 0.1, not 0.2.
  • Liver Function Test Reference Ranges in Normal Pregnancy — Scarborough, Hull and York Pathology Service, York and Scarborough Teaching Hospitals NHS Foundation Trust, 2022 · Laboratory / reference-interval sourceNon-pregnant adult total bilirubin below 21 µmol/L, with no lower limit. Matches Sera's upper edge of 21 µmol/L.
  • Assessing liver function and interpreting liver blood tests — NHS Specialist Pharmacy Service, 2024 · Government / public-health guidanceNormal bilirubin 5 to 21 µmol/L. Matches the upper edge of 21 and is the only source found that quotes a lower limit (5 µmol/L, Sera's optimal floor).
  • Guidelines on the management of abnormal liver blood tests — Newsome PN, Cramb R, Davison SM, et al. — Gut (British Society of Gastroenterology), 2018 · Clinical guidelineAn isolated raised bilirubin is most often Gilbert's syndrome, which is not associated with liver disease or ill health. Supports the note, not a band edge.

Last reviewed: November 9, 2026 · Total bilirubin on its own page

Bilirubin (Direct)Published reference intervalmg/dL · μmol/L

The part of bilirubin the liver has already processed and made water-soluble, ready to leave in bile. Also called conjugated bilirubin.

UnitOptimalSufficientOut of range
mg/dL0 – 0.3—below 0 or above 0.3
μmol/L0 – 5—below 0 or above 5

No separate Sufficient band is currently defined for this marker.

Interpretation: The band ends at the usual laboratory upper limit for direct (conjugated) bilirubin: less than 0.3 mg/dL, about 5 µmol/L (MedlinePlus; Roche method as used in NHS laboratories). The limit depends on the method: some laboratories report up to 0.4 mg/dL or 9 µmol/L, so read a borderline result against the laboratory's own range. This is a reference limit, not an optimal target; no narrower target has evidence behind it. A low or zero result is normal and is not flagged.

Sources

  • Bilirubin blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal direct (conjugated) bilirubin is less than 0.3 mg/dL (less than 5.1 µmol/L); total bilirubin is 0.1 to 1.2 mg/dL. Matches Sera's upper edge of 0.3 mg/dL and 5 µmol/L. Reviewed 2/13/2025.
  • Bilirubin (conjugated) — University Hospitals Sussex NHS Foundation Trust, Pathology, 2026 · Laboratory / reference-interval sourceAdult conjugated bilirubin 0 to 5 µmol/L, taken from the Roche Cobas Direct Bilirubin kit insert. Matches Sera's µmol/L row exactly. Last updated 19 May 2026.
  • Bilirubin (Direct, Conjugated) — University Hospitals Birmingham NHS Foundation Trust, Pathology tests database, 2026 · Laboratory / reference-interval sourceTwo sites of one trust use different limits: below 5 µmol/L at Heartlands and below 9 µmol/L at Queen Elizabeth. Shows that 5 is in use and that the limit depends on the method.
  • Bilirubin, Total/Direct, Serum (test 001214) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints a direct bilirubin interval of 0.00 to 0.40 mg/dL, slightly wider than Sera's 0.3. Report dated 2016; the interval may have been revised since.

Last reviewed: November 9, 2026 · Direct bilirubin on its own page

Bilirubin (Indirect)Sera practitioner target — source review pendingOne-sidedmg/dL · μmol/L

The part of bilirubin that has not yet been processed by the liver, carried in the blood attached to albumin. Also called unconjugated bilirubin.

UnitOptimalSufficientOut of range
mg/dL0.2 – 1—above 1
μmol/L3 – 17—above 17

No separate Sufficient band is currently defined for this marker.

Bounded on the high side only — a low result is not treated as out of range. No source treats a low indirect bilirubin as abnormal and the 0.2 mg/dL edge is unsourced.

Interpretation: Indirect (unconjugated) bilirubin is usually calculated as total minus direct, so it inherits the error of both measurements and few bodies publish a range for it. The upper edge of 1.0 mg/dL (17 µmol/L) has no published source behind it; Labcorp prints 0.1 to 0.8 mg/dL, and MedlinePlus gives only total (up to 1.2 mg/dL) and direct (below 0.3). A mildly raised indirect bilirubin with normal liver enzymes and a normal blood count is most often Gilbert syndrome; read it alongside total bilirubin and the laboratory's own range. A low result has no recognised meaning and is not flagged.

Sources

  • Bilirubin, Total/Direct, Serum (test 001214) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints an indirect bilirubin interval of 0.10 to 0.80 mg/dL. Sera's upper edge of 1.0 is higher and its lower edge of 0.2 is higher. Report dated 2016; the interval may have been revised since.
  • Bilirubin blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceGives total bilirubin 0.1 to 1.2 mg/dL and direct below 0.3 mg/dL, and no separate indirect range. Context only: it does not state Sera's 1.0 mg/dL edge.

Last reviewed: November 9, 2026

AlbuminPublished reference intervalg/dL · g/L

The most common protein in your blood. The liver makes it, and it keeps fluid in balance and carries hormones, vitamins, and medicines around the body.

UnitOptimalSufficientOut of range
g/dL4 – 53.5 – 5.5below 3.5 or above 5.5
g/L40 – 5035 – 55below 35 or above 55

Interpretation: The acceptable band of 3.5 to 5.5 g/dL (35 to 55 g/L) is a standard laboratory interval (Labcorp; MedlinePlus gives 3.4 to 5.4). UK laboratories use the harmonised 35 to 50 g/L, so a UK report will flag above 50 where Sera does not. The optimal band's upper edge of 5.0 g/dL is that UK upper limit. Its lower edge of 4.0 g/dL is a functional target with no specific published threshold: in a US cohort of 31,274 adults, mortality rose step by step below 4.6 g/dL, which supports preferring the upper part of the range rather than any single cut-off. Albumin falls with inflammation, liver disease and protein loss, and rises with dehydration. Albumin reported from protein electrophoresis reads lower than the routine dye-binding method and should not be compared with these bands.

Sources

  • Hepatic Function Panel (7) (test 322755) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints serum albumin 3.5 to 5.5 g/dL, the same as Sera's sufficient band. Report dated 2016; the interval may have been revised since.
  • Albumin blood (serum) test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal albumin is 3.4 to 5.4 g/dL (34 to 54 g/L), within 0.1 g/dL of Sera's sufficient band at both ends. Reviewed 2/13/2025.
  • Albumin — York and Scarborough Teaching Hospitals NHS Foundation Trust, Laboratory Medicine test directory, 2026 · Laboratory / reference-interval sourceUK harmonised adult range 35 to 50 g/L. The lower limit matches Sera's sufficient lower edge and the upper limit matches Sera's optimal upper edge of 50 g/L. The page is undated; opened October 2026.
  • Albumin — University Hospitals Birmingham NHS Foundation Trust, Pathology tests database, 2026 · Laboratory / reference-interval sourceAdults 35 to 50 g/L, sourced to the Pathology Harmony recommendations. Confirms the UK lower limit of 35 and upper limit of 50 g/L. Last updated 19 August 2026.
  • Serum albumin is incrementally associated with increased mortality across varying levels of kidney function — Brown-Tortorici AR, Naderi N, Tang Y, et al. — Nutrition, 2020 · Peer-reviewed publicationIn 31,274 US adults (NHANES 1999 to 2010), mortality rose progressively as albumin fell below 4.6 g/dL. Supports an optimal band in the upper part of the reference range; it does not identify 4.0 g/dL as a threshold.

Last reviewed: November 9, 2026 · Albumin on its own page

Albumin %Published reference intervalAssay-dependent%

The albumin band on a serum protein electrophoresis, as a percentage of total protein. Albumin as a concentration is its own marker.

UnitOptimalSufficientOut of range
%55.8 – 66.1—below 55.8 or above 66.1

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The albumin band of a serum protein electrophoresis as a share of total protein. The band of 55.8 to 66.1 % is the laboratory reference interval for the Sebia Capillarys capillary method, printed by two laboratories that name the method. Agarose gel draws the albumin zone differently and gives a higher interval of about 60 to 72 %, so a gel result should be read against its own report. Read the percentage beside the concentration, since a change in total protein moves every percentage even when the fraction itself has not, and against the range printed on the report, since intervals differ between instruments. Read it with the albumin concentration, which is its own marker.

Sources

  • SPEP with reflex to immunotyping (test code SPEP) — CRMC laboratory test catalogue (AP Green Special Chemistry), 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys 3: albumin 55.8 to 66.1 % of total protein, the interval Sera's band follows.
  • Protein Electrophoresis, Serum (LAB119) — University of Vermont Medical Center laboratory, via the Porter Medical Center test catalogue, 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys Tera 3: albumin 55.8 to 66.1 % of total protein, the same interval as the Capillarys 3.
  • Proteinelektrophorese (ELPHO), Hydrasys 2 agarose gel, revised 2023 — Universitätsklinikum Ulm, Klinische Chemie, 2023 · Laboratory / reference-interval sourceAgarose gel on the Sebia Hydrasys 2: albumin 59.8 to 72.4 % of total protein. Cited for the method difference, not for Sera's band, which follows the capillary method.

Last reviewed: November 9, 2026

Total ProteinPublished reference intervalg/dL · g/L

The total of all the proteins in your blood, mainly albumin plus the globulins. The liver makes most of it, so it reflects liver capacity, nutrition, hydration, and immune activity.

UnitOptimalSufficientOut of range
g/dL6.5 – 86 – 8.3below 6 or above 8.3
g/L65 – 8060 – 83below 60 or above 83

Interpretation: The acceptable band of 6.0 to 8.3 g/dL (60 to 83 g/L) is a standard laboratory interval (University of Michigan; Labcorp prints 6.0 to 8.5). The optimal band of 6.5 to 8.0 g/dL follows the narrower published intervals: MedlinePlus gives 6.5 to 8.1 g/dL, and UK laboratories use 60 to 80 g/L, so a UK report flags above 80. Both tiers are reference intervals; no outcome study defines an optimal total protein. Total protein is albumin plus globulin, so an abnormal result is read by looking at which of the two has moved.

Sources

  • Protein Electrophoresis, Serum — Michigan Medicine Laboratories (MLabs), University of Michigan, 2026 · Laboratory / reference-interval sourceTotal protein 6.0 to 8.3 g/dL from age 12, the same as Sera's sufficient band. The page is undated; opened October 2026.
  • Hepatic Function Panel (7) (test 322755) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints total protein 6.0 to 8.5 g/dL. Confirms the lower limit of 6.0; its upper limit is 0.2 above Sera's. Report dated 2016.
  • Total protein — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal total protein is 6.5 to 8.1 g/dL (65 to 81 g/L). Matches Sera's optimal lower edge of 6.5 and sits 0.1 above its optimal upper edge of 8.0. Reviewed 5/19/2025.
  • Total Protein — York and Scarborough Teaching Hospitals NHS Foundation Trust, Laboratory Medicine test directory, 2026 · Laboratory / reference-interval sourceUK harmonised range 60 to 80 g/L. Matches Sera's sufficient lower edge of 60 and optimal upper edge of 80 g/L. The page is undated; opened October 2026.
  • Total Protein — Worcestershire Acute Hospitals NHS Trust, Pathology tests A to Z, 2026 · Laboratory / reference-interval sourceTotal protein 60 to 80 g/L, the same UK range from a second trust. The page is undated; opened October 2026.

Last reviewed: November 9, 2026 · Total Protein on its own page

GlobulinPublished reference intervalg/dL · g/L

A mixed group of blood proteins that includes antibodies, transport proteins, and clotting factors, made by the liver and immune system. It is usually worked out as total protein minus albumin.

UnitOptimalSufficientOut of range
g/dL2.4 – 32 – 3.5below 2 or above 3.5
g/L24 – 3020 – 35below 20 or above 35

Interpretation: Globulin is calculated as total protein minus albumin, so the range shifts with the laboratory's methods. The acceptable band of 2.0 to 3.5 g/dL (20 to 35 g/L) uses published limits: a lower limit of 2.0 g/dL (University of Washington) and an upper limit of 35 g/L from a 2026 Irish reference-interval study; other laboratories go as wide as 18 to 39 g/L. A low result matters: a calculated globulin under about 19 g/L is a validated screening cut-off for antibody deficiency and is worth following with immunoglobulins. A high result points to inflammation, chronic infection, liver disease or a paraprotein and is followed with protein electrophoresis. The optimal band of 2.4 to 3.0 g/dL is a functional-practice convention with no published evidence behind it.

Sources

  • Establishment of a reference interval for calculated globulin on the Roche platform — Flannery C, Griffin A, Quinn J, Loughrey C, Srinivasan S — Annals of Clinical Biochemistry, 2026 · Peer-reviewed publicationIn 310 selected Irish primary-care adults (CLSI direct method) the calculated globulin reference interval was 23 to 35 g/L; an indirect estimate from 8,466 patients gave 22 to 37 g/L. The upper limit matches Sera's sufficient upper edge of 35 g/L. Specific to Roche total protein and BCG albumin methods.
  • Globulin (GLOB) — University of Washington, Department of Laboratory Medicine and Pathology test guide, 2015 · Laboratory / reference-interval sourceGlobulin 2.0 to 3.9 g/dL for both sexes. The lower limit matches Sera's sufficient lower edge. Effective date 03/01/2015 and still the interval displayed on the live test guide in October 2026.
  • Total Protein — Worcestershire Acute Hospitals NHS Trust, Pathology tests A to Z, 2026 · Laboratory / reference-interval sourceGlobulin 18 to 36 g/L. Brackets Sera's sufficient band of 20 to 35 g/L, which is slightly narrower at both ends. The page is undated; opened October 2026.
  • Protein Electrophoresis, Serum (test 001487) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints total globulin 2.2 to 3.9 g/dL. Its upper limit is 0.4 above Sera's 3.5. Report dated 2016.
  • Validation of Calculated Globulin (CG) as a Screening Test for Antibody Deficiency in an Italian University Hospital — Pecoraro A, Jolles S, Crescenzi L, et al. — Current Pharmaceutical Biotechnology, 2018 · Peer-reviewed publicationA calculated globulin cut-off of 19 g/L detected adults with IgG below 600 mg/dL with 70% sensitivity and 75% specificity, and picked up 37 of 38 known CVID patients. Supports flagging a low result at about Sera's lower edge of 20 g/L.

Last reviewed: November 9, 2026 · Globulin on its own page

A/G Ratio (Albumin/Globulin)Published reference interval

Albumin divided by the globulins: one number for the balance between the protein the liver makes most of and the proteins of the immune system.

UnitOptimalSufficientOut of range
ratio1 – 2.4—below 1 or above 2.4

No separate Sufficient band is currently defined for this marker.

Interpretation: The A/G ratio is albumin divided by globulin, where globulin is usually total protein minus albumin. No guideline sets a value: each laboratory establishes its own interval. A chemistry-panel ratio is typically read against about 1.0 to 2.4. A ratio calculated from protein electrophoresis measures albumin differently and carries its own interval, which varies widely between laboratories (0.7 to 2.0 and 0.88 to 2.30 in two US laboratories; some European reports print a narrower range), so read an electrophoresis ratio against the range printed on the report. A low ratio means low albumin, raised globulins or both, and is the direction that matters; a high ratio has no established meaning on its own. There is no evidence for a narrower optimal range.

Sources

  • Albumin/Globulin Ratio (AGR) — University of Washington Department of Laboratory Medicine and Pathology, 2026 · Laboratory / reference-interval sourceChemistry-panel A/G ratio with a reference range of 1.0 to 2.4 for both sexes. Sera's proposed 1.1 to 2.5 sits 0.1 higher at each end.
  • Protein Electrophoresis, Serum — University of Michigan, MLabs, 2026 · Laboratory / reference-interval sourceCapillary electrophoresis: albumin/globulin ratio 0.88 to 2.30. An electrophoresis-derived ratio here has a lower floor than Sera's proposed 1.1 and a lower ceiling than 2.5.
  • Protein Electrophoresis — University of Florida Health Pathology Laboratories, 2026 · Laboratory / reference-interval sourceCapillary electrophoresis: A:G ratio 0.7 to 2.0. This is a second electrophoresis-derived interval, and it differs from Michigan's, from the chemistry interval and from Sera's proposed band.
  • The Importance of Verifying Reference Intervals for Calculated Results (JALM Talk) — Association for Diagnostics and Laboratory Medicine — Journal of Applied Laboratory Medicine, 2017 · Professional societyStates that no guideline-based values exist for the A/G ratio, that each laboratory must establish its own interval, and that a change of albumin method changes the interval. It gives no numbers.

Last reviewed: November 9, 2026 · A/G ratio on its own page

Serum protein electrophoresis12 markers

Alpha-1 GlobulinPublished reference intervalAssay-dependentg/dL · g/L

The alpha-1 fraction from serum protein electrophoresis, chiefly alpha-1 antitrypsin and alpha-1 acid glycoprotein.

UnitOptimalSufficientOut of range
g/dL0.2 – 0.4—below 0.2 or above 0.4
g/L2 – 4—below 2 or above 4

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: An acute-phase fraction, so a raised value is non-specific and rarely the point. The finding worth chasing is a conspicuously low alpha-1, which raises alpha-1 antitrypsin deficiency: a diagnosis rather than a pattern, and one worth confirming directly. The band of 0.2 to 0.4 g/dL (2 to 4 g/L) is the MedlinePlus interval, in line with ARUP (0.19 to 0.46) and the University of Michigan (0.21 to 0.44). Fractions depend on the electrophoresis method, with one laboratory reporting 0.3 to 0.6, so the range printed on the report takes precedence.

Sources

  • Protein electrophoresis - serum — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2026 · Government / public-health guidanceNormal alpha-1 globulin is 0.2 to 0.4 g/dL (2 to 4 g/L). Sera's band of 0.1 to 0.3 is one step lower at both ends. Reviewed 1/29/2026.
  • Protein Electrophoresis, Serum (test 001487) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints alpha-1 globulin 0.0 to 0.4 g/dL. Supports an upper limit of 0.4, not Sera's 0.3. Report dated 2016.
  • Protein Electrophoresis, Serum (0050640) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceAlpha-1 globulin 0.19 to 0.46 g/dL. Supports a lower limit of about 0.2 and an upper limit above 0.4. The page is undated; opened October 2026.
  • Protein Electrophoresis, Serum — Michigan Medicine Laboratories (MLabs), University of Michigan, 2026 · Laboratory / reference-interval sourceAlpha-1 globulin 0.21 to 0.44 g/dL. Supports 0.2 to 0.4. The page is undated; opened October 2026.
  • Protein Electrophoresis (Serum) — University of Iowa Health Care, Laboratory Services Handbook, 2023 · Laboratory / reference-interval sourceAlpha-1 0.3 to 0.6 g/dL, higher than the other laboratories, showing how far the fraction moves with method. Capillary electrophoresis; the page says its reference ranges changed on 10/17/2023.

Last reviewed: November 9, 2026 · Alpha-1 Globulin on its own page

Alpha-1 Globulin %Published reference intervalAssay-dependent%

The alpha-1 fraction as a percentage of total protein, the second figure most electrophoresis reports print beside the concentration.

UnitOptimalSufficientOut of range
%2.9 – 4.9—below 2.9 or above 4.9

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The alpha-1 fraction as a share of total protein. The band of 2.9 to 4.9 % is the laboratory reference interval for the Sebia Capillarys capillary method, printed by two laboratories that name the method. Agarose gel gives a much lower interval of about 1 to 3 %, so a gel result should be read against its own report. A low share can reflect low alpha-1 antitrypsin and is worth following up. Read the percentage beside the concentration, since a change in total protein moves every percentage even when the fraction itself has not, and against the range printed on the report, since intervals differ between instruments.

Sources

  • SPEP with reflex to immunotyping (test code SPEP) — CRMC laboratory test catalogue (AP Green Special Chemistry), 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys 3: alpha-1 globulins 2.9 to 4.9 % of total protein, the interval Sera's band follows.
  • Protein Electrophoresis, Serum (LAB119) — University of Vermont Medical Center laboratory, via the Porter Medical Center test catalogue, 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys Tera 3: alpha-1 globulins 2.9 to 4.9 % of total protein, the same interval as the Capillarys 3.
  • Proteinelektrophorese (ELPHO), Hydrasys 2 agarose gel, revised 2023 — Universitätsklinikum Ulm, Klinische Chemie, 2023 · Laboratory / reference-interval sourceAgarose gel on the Sebia Hydrasys 2: alpha-1 globulins 1.0 to 3.2 % of total protein. Cited for the method difference, not for Sera's band, which follows the capillary method.

Last reviewed: November 9, 2026

Alpha-2 GlobulinPublished reference intervalAssay-dependentg/dL · g/L

The alpha-2 fraction from serum protein electrophoresis, chiefly haptoglobin, alpha-2 macroglobulin and ceruloplasmin.

UnitOptimalSufficientOut of range
g/dL0.6 – 1—below 0.6 or above 1
g/L6 – 10—below 6 or above 10

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Rises with inflammation and tissue injury, and markedly in nephrotic syndrome, where alpha-2 macroglobulin is too large to be lost in the urine while smaller proteins are. A low alpha-2 points the other way, at haemolysis consuming haptoglobin. The band of 0.6 to 1.0 g/dL (6 to 10 g/L) takes its lower limit from MedlinePlus and its upper limit from Labcorp; the University of Michigan prints 0.54 to 0.97. Some laboratories set the lower limit at 0.4 to 0.5, so check a borderline low against the report's own range.

Sources

  • Protein electrophoresis - serum — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2026 · Government / public-health guidanceNormal alpha-2 globulin is 0.6 to 0.9 g/dL (6 to 9 g/L). The lower limit matches Sera's 0.6; the upper is 0.1 below Sera's 1.0. Reviewed 1/29/2026.
  • Protein Electrophoresis, Serum (test 001487) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints alpha-2 globulin 0.4 to 1.0 g/dL. The upper limit matches Sera's 1.0. Report dated 2016.
  • Protein Electrophoresis, Serum (0050640) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceAlpha-2 globulin 0.48 to 1.05 g/dL. Supports an upper limit of about 1.0; its lower limit is below Sera's 0.6. The page is undated; opened October 2026.
  • Protein Electrophoresis, Serum — Michigan Medicine Laboratories (MLabs), University of Michigan, 2026 · Laboratory / reference-interval sourceAlpha-2 globulin 0.54 to 0.97 g/dL, close to Sera's 0.6 to 1.0. The page is undated; opened October 2026.
  • Protein Electrophoresis (Serum) — University of Iowa Health Care, Laboratory Services Handbook, 2023 · Laboratory / reference-interval sourceAlpha-2 0.3 to 0.8 g/dL, lower than the other laboratories, showing the method dependence. Capillary electrophoresis; the page says its reference ranges changed on 10/17/2023.

Last reviewed: November 9, 2026 · Alpha-2 Globulin on its own page

Alpha-2 Globulin %Published reference intervalAssay-dependent%

The alpha-2 fraction as a percentage of total protein, the second figure most electrophoresis reports print beside the concentration.

UnitOptimalSufficientOut of range
%7.1 – 11.8—below 7.1 or above 11.8

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The alpha-2 fraction as a share of total protein. The band of 7.1 to 11.8 % is the laboratory reference interval for the Sebia Capillarys capillary method, printed by two laboratories that name the method. Read the percentage beside the concentration, since a change in total protein moves every percentage even when the fraction itself has not, and against the range printed on the report, since intervals differ between instruments.

Sources

  • SPEP with reflex to immunotyping (test code SPEP) — CRMC laboratory test catalogue (AP Green Special Chemistry), 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys 3: alpha-2 globulins 7.1 to 11.8 % of total protein, the interval Sera's band follows.
  • Protein Electrophoresis, Serum (LAB119) — University of Vermont Medical Center laboratory, via the Porter Medical Center test catalogue, 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys Tera 3: alpha-2 globulins 7.1 to 11.8 % of total protein, the same interval as the Capillarys 3.
  • Proteinelektrophorese (ELPHO), Hydrasys 2 agarose gel, revised 2023 — Universitätsklinikum Ulm, Klinische Chemie, 2023 · Laboratory / reference-interval sourceAgarose gel on the Sebia Hydrasys 2: alpha-2 globulins 7.4 to 12.6 % of total protein. Cited for the method difference, not for Sera's band, which follows the capillary method.

Last reviewed: November 9, 2026

Beta GlobulinPublished reference intervalAssay-dependentg/dL · g/L

The beta fraction from serum protein electrophoresis, chiefly transferrin, complement components and beta-lipoproteins.

UnitOptimalSufficientOut of range
g/dL0.7 – 1.2—below 0.7 or above 1.2
g/L7 – 12—below 7 or above 12

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Read against iron studies first: transferrin sits in this fraction and rises in iron deficiency, which is the commonest cause of a raised beta. Some laboratories split beta-1 and beta-2, and those figures are not interchangeable with a combined one. The lower edge of 0.7 g/dL (7 g/L) is Labcorp's. The upper edge of 1.2 g/dL falls between published limits: MedlinePlus, ARUP and the University of Iowa end at 1.1 and Labcorp at 1.3, so read a result of 1.1 to 1.3 against the report's own range.

Sources

  • Protein electrophoresis - serum — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2026 · Government / public-health guidanceNormal beta globulin is 0.6 to 1.1 g/dL (6 to 11 g/L), 0.1 below Sera's band at both ends. Reviewed 1/29/2026.
  • Protein Electrophoresis, Serum (test 001487) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints beta globulin 0.7 to 1.3 g/dL. The lower limit matches Sera's 0.7; the upper is 0.1 above Sera's 1.2. Report dated 2016.
  • Protein Electrophoresis, Serum (0050640) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceBeta globulin 0.48 to 1.10 g/dL. Upper limit 1.1, below Sera's 1.2. The page is undated; opened October 2026.
  • Protein Electrophoresis, Serum — Michigan Medicine Laboratories (MLabs), University of Michigan, 2026 · Laboratory / reference-interval sourceBeta globulin 0.65 to 1.03 g/dL. Lower limit close to Sera's 0.7; upper limit below Sera's 1.2. The page is undated; opened October 2026.
  • Protein Electrophoresis (Serum) — University of Iowa Health Care, Laboratory Services Handbook, 2023 · Laboratory / reference-interval sourceBeta 0.5 to 1.1 g/dL for the combined fraction; the page notes capillary electrophoresis can split beta-1 and beta-2 but a range exists only for total beta. Capillary electrophoresis; the page says its reference ranges changed on 10/17/2023.

Last reviewed: November 9, 2026 · Beta Globulin on its own page

Beta Globulin %Published reference intervalAssay-dependent%

The combined beta fraction as a percentage of total protein, the second figure most electrophoresis reports print beside the concentration.

UnitOptimalSufficientOut of range
%8.4 – 13.1—below 8.4 or above 13.1

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The beta fraction as a share of total protein, for reports that give beta as one fraction. The band of 8.4 to 13.1 % is the laboratory reference interval of a capillary method (Sebia Capillarys Tera 3) at one laboratory. Agarose gel gives about 7.5 to 12.9 %. Where a report splits beta into beta-1 and beta-2, those are read as their own markers. Read the percentage beside the concentration, since a change in total protein moves every percentage even when the fraction itself has not, and against the range printed on the report, since intervals differ between instruments.

Sources

  • Protein Electrophoresis, Serum (LAB119) — University of Vermont Medical Center laboratory, via the Porter Medical Center test catalogue, 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys Tera 3: beta globulins 8.4 to 13.1 % of total protein, the same interval as the Capillarys 3.
  • Proteinelektrophorese (ELPHO), Hydrasys 2 agarose gel, revised 2023 — Universitätsklinikum Ulm, Klinische Chemie, 2023 · Laboratory / reference-interval sourceAgarose gel on the Sebia Hydrasys 2: beta globulins 7.5 to 12.9 % of total protein. Cited for the method difference, not for Sera's band, which follows the capillary method.

Last reviewed: November 9, 2026

Beta-1 GlobulinPublished reference intervalAssay-dependentg/dL · g/L

The first half of the beta fraction on capillary electrophoresis, made up mostly of transferrin.

UnitOptimalSufficientOut of range
g/dL0.3 – 0.6—below 0.3 or above 0.6
g/L3 – 6—below 3 or above 6

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Capillary electrophoresis splits the beta zone in two; beta-1 is mainly transferrin. The band is a laboratory reference interval for the Sebia Capillarys method: 4.7 to 7.2 % of total protein, or 0.3 to 0.6 g/dL (3.0 to 6.0 g/L). Intervals differ between laboratories and instruments, and many laboratories report only a total beta fraction, so read the result against the range printed on the report. Beta-1 rises with transferrin in iron deficiency, pregnancy and oestrogen use, and a haemolysed sample can distort the zone. No guideline sets a threshold for this fraction, and there is no evidence for a narrower optimal range.

Sources

  • SPEP with reflex to immunotyping (test code SPEP) — CRMC laboratory test catalogue (AP Green Special Chemistry), 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys 3: beta-1 globulins 4.7 to 7.2 % and 0.3 to 0.6 g/dL. The percentage interval is identical to Sera's proposed band; the g/dL interval is wider than Sera's proposed 0.34 to 0.52.
  • Protein Electrophoresis, Serum (Orderable - PELS) — London Health Sciences Centre and St. Joseph's Health Care London, Pathology and Laboratory Medicine, 2026 · Laboratory / reference-interval sourceSebia capillary electrophoresis: beta 1 reference range 3.0 to 6.0 g/L. This agrees with the 0.3 to 0.6 g/dL interval and is wider than Sera's proposed 3.4 to 5.2 g/L.

Last reviewed: November 9, 2026

Beta-1 Globulin %Published reference intervalAssay-dependent%

The beta-1 fraction (mostly transferrin) as a percentage of total protein, the second figure most electrophoresis reports print beside the concentration.

UnitOptimalSufficientOut of range
%4.7 – 7.2—below 4.7 or above 7.2

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The beta-1 fraction as a share of total protein. The band of 4.7 to 7.2% is the laboratory reference interval for the Sebia Capillarys method, the system that splits beta in two. Read the percentage beside the concentration, since a change in total protein moves every percentage even when the fraction itself has not, and against the range printed on the report, since intervals differ between instruments.

Sources

  • SPEP with reflex to immunotyping (test code SPEP) — CRMC laboratory test catalogue (AP Green Special Chemistry), 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys 3: beta-1 globulins 4.7 to 7.2 % and 0.3 to 0.6 g/dL. The percentage interval is identical to Sera's proposed band; the g/dL interval is wider than Sera's proposed 0.34 to 0.52.

Last reviewed: November 9, 2026

Beta-2 GlobulinPublished reference intervalAssay-dependentg/dL · g/L

The second half of the beta fraction on capillary electrophoresis, made up mostly of complement C3, with IgA running alongside.

UnitOptimalSufficientOut of range
g/dL0.2 – 0.5—below 0.2 or above 0.5
g/L2 – 5—below 2 or above 5

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Capillary electrophoresis splits the beta zone in two; beta-2 is mainly complement C3. The band is a laboratory reference interval for the Sebia Capillarys method: 3.2 to 6.5 % of total protein, or 0.2 to 0.5 g/dL (2.0 to 5.0 g/L; one Canadian laboratory prints an upper limit of 5.4 g/L). Intervals differ between laboratories and instruments, and many laboratories report only a total beta fraction, so read the result against the range printed on the report. C3 breaks down in an old or poorly stored sample, which lowers beta-2, and a monoclonal band, fibrinogen in a plasma sample or a raised IgA can sit in this zone and raise it. No guideline sets a threshold for this fraction, and there is no evidence for a narrower optimal range.

Sources

  • SPEP with reflex to immunotyping (test code SPEP) — CRMC laboratory test catalogue (AP Green Special Chemistry), 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys 3: beta-2 globulins 3.2 to 6.5 % and 0.2 to 0.5 g/dL. The percentage interval is identical to Sera's proposed band; the g/dL interval is slightly wider than Sera's proposed 0.23 to 0.47.
  • Protein Electrophoresis, Serum (Orderable - PELS) — London Health Sciences Centre and St. Joseph's Health Care London, Pathology and Laboratory Medicine, 2026 · Laboratory / reference-interval sourceSebia capillary electrophoresis: beta 2 reference range 2.0 to 5.4 g/L. The lower edge matches 0.2 g/dL; the upper edge is higher than both the 0.5 g/dL interval and Sera's proposed 4.7 g/L.

Last reviewed: November 9, 2026

Beta-2 Globulin %Published reference intervalAssay-dependent%

The beta-2 fraction (mostly complement C3) as a percentage of total protein, the second figure most electrophoresis reports print beside the concentration.

UnitOptimalSufficientOut of range
%3.2 – 6.5—below 3.2 or above 6.5

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The beta-2 fraction as a share of total protein. The band of 3.2 to 6.5% is the laboratory reference interval for the Sebia Capillarys method, the system that splits beta in two. Read the percentage beside the concentration, since a change in total protein moves every percentage even when the fraction itself has not, and against the range printed on the report, since intervals differ between instruments.

Sources

  • SPEP with reflex to immunotyping (test code SPEP) — CRMC laboratory test catalogue (AP Green Special Chemistry), 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys 3: beta-2 globulins 3.2 to 6.5 % and 0.2 to 0.5 g/dL. The percentage interval is identical to Sera's proposed band; the g/dL interval is slightly wider than Sera's proposed 0.23 to 0.47.

Last reviewed: November 9, 2026

Gamma GlobulinPublished reference intervalAssay-dependentg/dL · g/L

The gamma fraction from serum protein electrophoresis — the immunoglobulins.

UnitOptimalSufficientOut of range
g/dL0.7 – 1.6—below 0.7 or above 1.6
g/L7 – 16—below 7 or above 16

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: A broad polyclonal rise reflects chronic infection, autoimmune disease or liver disease. A narrow discrete peak is monoclonal and is a different matter, warranting immunofixation and referral. Sera holds the quantity only: the shape of the peak lives on the densitometry trace and cannot be inferred from the number, so a normal gamma does not exclude a small paraprotein. The lower edge of 0.7 g/dL (7 g/L) is the University of Michigan lower limit. The upper edge of 1.6 g/dL falls between published limits: ARUP, Iowa and Michigan end at about 1.5, MedlinePlus and Labcorp at 1.8; 7 to 16 g/L is the published normal range for IgG, which makes up most of this fraction. A low gamma suggests antibody deficiency and is followed with immunoglobulins.

Sources

  • Protein electrophoresis - serum — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2026 · Government / public-health guidanceNormal gamma globulin is 0.8 to 1.8 g/dL (8 to 18 g/L), higher than Sera's 0.7 to 1.6 at both ends. Reviewed 1/29/2026.
  • Protein Electrophoresis, Serum (test 001487) sample report — Labcorp, 2016 · Laboratory / reference-interval sourceLabcorp's sample report prints gamma globulin 0.4 to 1.8 g/dL. Upper limit 1.8, above Sera's 1.6; lower limit well below Sera's 0.7. Report dated 2016.
  • Protein Electrophoresis, Serum (0050640) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceGamma 0.62 to 1.51 g/dL. Upper limit 1.5, just below Sera's 1.6. The page is undated; opened October 2026.
  • Protein Electrophoresis, Serum — Michigan Medicine Laboratories (MLabs), University of Michigan, 2026 · Laboratory / reference-interval sourceGamma globulin 0.70 to 1.47 g/dL. The lower limit matches Sera's 0.7; the upper is below Sera's 1.6. The page is undated; opened October 2026.
  • Protein Electrophoresis (Serum) — University of Iowa Health Care, Laboratory Services Handbook, 2023 · Laboratory / reference-interval sourceGamma 0.6 to 1.5 g/dL. Upper limit 1.5, just below Sera's 1.6. Capillary electrophoresis; the page says its reference ranges changed on 10/17/2023.
  • Quantitative immunoglobulins — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2026 · Government / public-health guidanceNormal IgG is 700 to 1600 mg/dL (7 to 16 g/L). These are the same numbers as Sera's gamma band, but IgG is a nephelometric immunoglobulin measurement, not the electrophoresis gamma fraction. Reviewed 1/29/2026.

Last reviewed: November 9, 2026 · Gamma Globulin on its own page

Gamma Globulin %Published reference intervalAssay-dependent%

The gamma fraction, the immunoglobulins, as a percentage of total protein, the second figure most electrophoresis reports print beside the concentration.

UnitOptimalSufficientOut of range
%11.1 – 18.8—below 11.1 or above 18.8

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The gamma fraction as a share of total protein. The band of 11.1 to 18.8 % is the laboratory reference interval for the Sebia Capillarys capillary method, printed by two laboratories that name the method. Agarose gel gives a lower interval of about 8 to 16 %, so a gel result should be read against its own report. Read the percentage beside the concentration, since a change in total protein moves every percentage even when the fraction itself has not, and against the range printed on the report, since intervals differ between instruments.

Sources

  • SPEP with reflex to immunotyping (test code SPEP) — CRMC laboratory test catalogue (AP Green Special Chemistry), 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys 3: gamma globulins 11.1 to 18.8 % of total protein, the interval Sera's band follows.
  • Protein Electrophoresis, Serum (LAB119) — University of Vermont Medical Center laboratory, via the Porter Medical Center test catalogue, 2026 · Laboratory / reference-interval sourceCapillary electrophoresis on the Sebia Capillarys Tera 3: gamma globulins 11.1 to 18.8 % of total protein, the same interval as the Capillarys 3.
  • Proteinelektrophorese (ELPHO), Hydrasys 2 agarose gel, revised 2023 — Universitätsklinikum Ulm, Klinische Chemie, 2023 · Laboratory / reference-interval sourceAgarose gel on the Sebia Hydrasys 2: gamma globulins 8.0 to 15.8 % of total protein. Cited for the method difference, not for Sera's band, which follows the capillary method.

Last reviewed: November 9, 2026

Kidney & Electrolytes · 21 markers

Filtration markers plus the electrolytes and minerals your kidneys regulate

CreatininePublished reference intervalSex-specificmg/dL · μmol/L

A waste product from normal muscle activity that the kidneys filter out of the blood.

UnitApplies toOptimalSufficientOut of range
mg/dLFemale0.6 – 0.90.59 – 1.04below 0.59 or above 1.04
mg/dLMale0.8 – 1.10.74 – 1.35below 0.74 or above 1.35
μmol/LFemale53 – 8052 – 92below 52 or above 92
μmol/LMale71 – 9765 – 119below 65 or above 119

Interpretation: Sex-specific, reflecting muscle mass rather than kidney function directly. Read alongside eGFR, which adjusts for age and sex. The acceptable band is a laboratory reference interval: 0.74 to 1.35 mg/dL in men and 0.59 to 1.04 in women (Mayo Clinic Laboratories). Other laboratories differ by about 0.1 mg/dL at each end. The narrower optimal band is a functional target with no published threshold behind it.

Sources

  • CRTS1 - Overview: Creatinine with Estimated Glomerular Filtration Rate (eGFR), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult serum creatinine reference values: men aged 15 and over 0.74 to 1.35 mg/dL, women aged 16 and over 0.59 to 1.04 mg/dL. These are the proposed sex-specific acceptable bands.
  • Creatinine blood test — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2025 · Government / public-health guidanceNormal result 0.7 to 1.3 mg/dL (62 to 115 umol/L) for men and 0.5 to 0.95 mg/dL (44 to 84 umol/L) for women. Confirms that the interval is sex-specific and that the women's upper limit sits near 1.0, not 1.2.
  • Creatinine (Pathology tests database) — University Hospitals Birmingham NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceUK adult serum creatinine interval: women 49 to 90 umol/L, men 64 to 104 umol/L (source given as Abbott Diagnostics). Corroborates sex-specific limits in SI units.

Last reviewed: November 9, 2026 · Creatinine on its own page

eGFR (Estimated)Established clinical thresholdAuto-calculatedOne-sidedmL/min/1.73m² · mL/min/1.73m2

An estimate of how well your kidneys filter waste from the blood. It is worked out from creatinine using the CKD-EPI 2021 formula. The name stands for estimated glomerular filtration rate.

Auto-calculated

CKD-EPI 2021 formula (creatinine, age, sex)

Calculated when Creatinine is recorded in the same blood test, after normalizing the inputs to the units the formula expects. Also needs the client’s age and sex from their record — without those this marker is not calculated at all.

UnitOptimalSufficientOut of range
mL/min/1.73m²90 – 12060 – 90below 60
mL/min/1.73m290 – 12060 – 90below 60

Bounded on the low side only — a high result is not treated as out of range. Laboratories report a high eGFR only as above 90, and no guideline sets an upper limit.

Interpretation: Bands follow KDIGO's CKD categories: G1 at 90 and above, G2 from 60 to 89, reduced function below 60. A single eGFR does not establish chronic kidney disease; KDIGO requires the finding to persist for three months. eGFR falls with age in people without kidney disease: the National Kidney Foundation gives an average of 116 at ages 20 to 29, 85 at 60 to 69 and 75 at 70 and over, so a result of 60 to 89 in an older adult is the age norm. There is no accepted upper threshold, so high results are not flagged.

Sources

Last reviewed: November 9, 2026 · eGFR on its own page

Creatinine Clearance (Cockcroft-Gault)No universal rangeAuto-calculatedUnbandedmL/min · unbanded

An estimate of kidney filtration from creatinine, age, sex and body weight, by the Cockcroft-Gault formula.

Auto-calculated

(140 − age) × weight (kg) ÷ (72 × creatinine (mg/dL)), × 0.85 for women

Calculated when Creatinine is recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

An estimate for adjusting drug doses, not a screen; eGFR carries the kidney band. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Calculated by the Cockcroft-Gault formula from creatinine, age, sex and the weight entered for the blood test. It is a drug-dosing estimate in mL/min, not a kidney screen, so it carries no band; eGFR is the kidney score. The FDA notes that actual body weight overestimates clearance in overweight or obese people, and the National Kidney Foundation advises moving to eGFR for medication decisions.

Sources

Last reviewed: November 9, 2026

Cystatin CPublished reference intervalOne-sidedmg/L · μg/mL

A small protein filtered freely by the glomerulus, used as a measure of kidney function that does not depend on muscle mass.

UnitOptimalSufficientOut of range
mg/L0.6 – 10.5 – 1.2above 1.2
μg/mL0.6 – 10.5 – 1.2above 1.2

Bounded on the high side only — a low result is not treated as out of range. No source gives a low cystatin C a clinical meaning, and 0.5 mg/L matches no published lower limit.

Interpretation: KDIGO recommends it specifically to confirm a borderline creatinine-based eGFR before diagnosing chronic kidney disease, because creatinine reflects muscle mass and cystatin C does not. Raised independently by thyroid dysfunction, corticosteroids and obesity, so those have to be excluded before reading it as kidney function. The bands are a laboratory reference interval, not a guideline threshold: Mayo Clinic Laboratories reports up to 1.03 mg/L under age 50 and up to 1.21 mg/L from 50, which is where the optimal and acceptable bands end. A low result has no published meaning and is not flagged.

Sources

Last reviewed: November 9, 2026 · Cystatin C on its own page

Beta-2 MicroglobulinPublished reference intervalOne-sidedmg/L · μg/mL

A small protein shed from the surface of nucleated cells, filtered by the glomerulus and reabsorbed by the tubule.

UnitOptimalSufficientOut of range
mg/L0.8 – 2.40.6 – 2.7above 2.7
μg/mL0.8 – 2.40.6 – 2.7above 2.7

Bounded on the high side only — a low result is not treated as out of range. No source gives a low beta-2 microglobulin a clinical meaning, and laboratory lower limits differ twofold (0.6 against 1.21).

Interpretation: Answers two different questions with one number. Filtered freely and reabsorbed proximally, so it tracks filtration much as cystatin C does; it also rises with cell turnover, which is where its prognostic weight in myeloma and lymphoma comes from. A raised value needs the clinical context before it means kidney disease. The bands are laboratory reference limits and differ by method: Labcorp's adult interval ends at 2.4 mg/L and Mayo Clinic Laboratories' at 2.7. A low result has no published meaning and is not flagged.

Sources

  • β2-Microglobulin — Labcorp, 2026 · Laboratory / reference-interval sourceAdult (over 18) serum reference interval 0.6 to 2.4 mg/L in both sexes. Matches Sera's optimal upper edge of 2.4 and acceptable lower edge of 0.6.
  • B2M - Overview: Beta-2-Microglobulin, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference values 1.21 to 2.70 mcg/mL by nephelometry; below 4 mcg/mL is a good prognostic factor in multiple myeloma. 2.7 is the highest published upper limit found and is the proposed acceptable upper edge.

Last reviewed: November 9, 2026 · Beta-2 Microglobulin on its own page

SodiumPublished reference intervalmEq/L · mmol/L

An important electrolyte that controls fluid balance, kept in check by the kidneys.

UnitOptimalSufficientOut of range
mEq/L138 – 142135 – 145below 135 or above 145
mmol/L138 – 142135 – 145below 135 or above 145

Interpretation: The acceptable band is the laboratory reference interval, 135 to 145 mmol/L (MedlinePlus, Mayo Clinic Laboratories); the European guideline defines hyponatraemia as below 135. UK laboratories use a slightly wider harmonised interval of 133 to 146. The optimal band of 138 to 142 comes from a US cohort followed for 25 years, in which that range carried the lowest risk of chronic disease and early death and risk rose above 142. That finding is an association: it has not been shown that changing sodium or fluid intake changes the outcome.

Sources

  • Sodium blood test — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2025 · Government / public-health guidanceNormal blood sodium is 135 to 145 mEq/L. Matches Sera's upper edge of 145; the lower edge is 135, not Sera's 136.
  • ELPSR - Overview: Electrolyte Panel, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceSerum sodium reference values from age 1: 135 to 145 mmol/L. Same interval as MedlinePlus.
  • Clinical practice guideline on diagnosis and treatment of hyponatraemia — Spasovski G, Vanholder R, Allolio B, et al. — Nephrology Dialysis Transplantation (European Renal Best Practice, ESE, ESICM), 2014 · Clinical guidelineDefines hyponatraemia as serum sodium below 135 mmol/L. Published 2014; no later edition of this European guideline was found, so it is cited as the edition in force. Supports a lower edge of 135.
  • Sodium (Pathology tests database) — University Hospitals Birmingham NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceUK harmonised interval (Pathology Harmony) 133 to 146 mmol/L, one to two units wider than the US interval at each end.
  • Middle-age high normal serum sodium as a risk factor for accelerated biological aging, chronic diseases, and premature mortality — Dmitrieva NI, Gagarin A, Liu D, et al. — eBioMedicine, 2023 · Peer-reviewed publicationUS cohort (ARIC, 11,255 adults, 25 years): sodium of 138 to 142 mmol/L carried the lowest risk of chronic disease and premature death; above 142 the risk of chronic disease was 39% higher. Matches Sera's optimal band of 138 to 142. Observational, not causal.

Last reviewed: November 9, 2026 · Sodium on its own page

PotassiumPublished reference intervalmEq/L · mmol/L

An important electrolyte for the heart and muscles, balanced by the kidneys.

UnitOptimalSufficientOut of range
mEq/L4 – 4.53.5 – 5below 3.5 or above 5
mmol/L4 – 4.53.5 – 5below 3.5 or above 5

Interpretation: Haemolysis during collection raises potassium artefactually. An unexpected high value is worth repeating before it is interpreted. The acceptable band of 3.5 to 5.0 mmol/L is the conventional interval; in a pooled analysis of 1.2 million people, mortality was higher outside it. Laboratory upper limits run slightly higher, 5.2 in the US sources and 5.3 in the UK, so a result of 5.1 to 5.3 may be printed as normal on the report. The optimal band of 4.0 to 4.5 is where the same analysis found the lowest risk; that is an association, not a treatment target.

Sources

  • Serum potassium and adverse outcomes across the range of kidney function: a CKD Prognosis Consortium meta-analysis — Kovesdy CP, Matsushita K, Sang Y, et al. — European Heart Journal, 2018 · Peer-reviewed publicationPooled 27 international cohorts (1,217,986 people): mortality was lowest at potassium 4 to 4.5 mmol/L and higher outside 3.5 to 5 mmol/L. Supports Sera's acceptable band of 3.5 to 5.0 and an optimal band of 4.0 to 4.5. The cohorts include some outside Europe and North America.
  • Potassium (Pathology tests database) — University Hospitals Birmingham NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceUK harmonised adult interval (Pathology Harmony) 3.5 to 5.3 mmol/L. Matches Sera's lower edge of 3.5; the upper limit is 0.3 higher than Sera's.
  • ELPSR - Overview: Electrolyte Panel, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceSerum potassium reference values from age 1: 3.6 to 5.2 mmol/L. Upper limit 0.2 above Sera's 5.0.
  • Potassium test — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2025 · Government / public-health guidanceNormal range 3.7 to 5.2 mEq/L. Upper limit 0.2 above Sera's 5.0.

Last reviewed: November 9, 2026 · Potassium on its own page

Sodium:Potassium RatioNo universal rangeAuto-calculatedUnbandedUnitless · unbanded

Serum sodium divided by serum potassium.

Auto-calculated

Sodium ÷ Potassium (mmol/L)

Calculated when Sodium and Potassium are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

No published interval exists for the ratio in human serum. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Calculated as sodium divided by potassium. No published interval exists for the ratio in human serum: the 30 to 35 target used in functional practice has no peer-reviewed support, and the studies that do exist are of urine or of animals. Read sodium and potassium against their own bands.

Sources

There is no band here to attribute to a source.

Last reviewed: November 9, 2026

ChloridePublished reference intervalmEq/L · mmol/L

A major electrolyte that works with sodium to control fluid balance, blood pressure, and the body's acid-base balance.

UnitOptimalSufficientOut of range
mEq/L100 – 10698 – 108below 98 or above 108
mmol/L100 – 10698 – 108below 98 or above 108

Interpretation: The acceptable band runs from the US laboratory lower limit of 98 mmol/L (MedlinePlus, Mayo Clinic Laboratories) to the UK harmonised upper limit of 108. US laboratories usually stop at 107 and UK laboratories start at 95, so the range printed on the report may differ by a unit or two. The optimal band of 100 to 106 is a functional target with no published evidence behind it. Chloride is read with sodium and bicarbonate rather than on its own.

Sources

  • Chloride test - blood — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2025 · Government / public-health guidanceTypical normal range 98 to 107 mEq/L. Matches Sera's lower edge of 98; the upper limit is one unit below Sera's 108.
  • ELPSR - Overview: Electrolyte Panel, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult serum chloride reference values: 98 to 107 mmol/L. Same interval as MedlinePlus.
  • Chloride (Pathology tests database) — University Hospitals Birmingham NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceUK harmonised interval (Pathology Harmony) 95 to 108 mmol/L. Matches Sera's upper edge of 108.

Last reviewed: November 9, 2026 · Chloride on its own page

Anion GapExploratory indexAuto-calculatedmmol/L

Sodium minus the sum of chloride and bicarbonate, the conventional measure of unmeasured anions.

Auto-calculated

Sodium − (Chloride + Bicarbonate), all mmol/L

Calculated when Sodium and Chloride and Bicarbonate (CO2 / Total CO2) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
mmol/L8 – 126 – 14below 6 or above 14

Interpretation: The first branch point in an acid–base problem: a metabolic acidosis with a raised gap points at lactate, ketones, kidney failure or a toxin, while a normal gap points at bicarbonate loss from gut or kidney. It falls with low albumin, itself an unmeasured anion, so correct for albumin before calling a gap normal in an unwell client. Sera computes it without the potassium term, which is the more common of the two conventions. Read it as an exploratory index rather than a diagnostic test: published laboratory ranges for this formula run from 2 to 13 mmol/L to 7 to 15, depending on the analyser, and Sera's bands match none of them exactly.

Sources

  • ELPSR - Overview: Electrolyte Panel, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAnion gap reference values from age 7: 7 to 15. The highest of the three intervals found.
  • Anion Gap | MLabs — University of Michigan, Michigan Medicine Laboratories, 2026 · Laboratory / reference-interval sourceReference range 2 to 13 mmol/L, calculated as sodium minus chloride plus CO2, the same formula Sera uses.
  • Anion Gap — North Bristol NHS Trust, Severn Pathology, 2026 · Laboratory / reference-interval sourceReference range 3 to 11 mmol/L; the page does not state the formula.
  • Anion Gap Blood Test — MedlinePlus, U.S. National Library of Medicine, 2024 · Government / public-health guidanceGives no numeric normal range and states that normal results vary by laboratory.

Last reviewed: November 9, 2026 · Anion Gap on its own page

UreaPublished reference intervalmmol/L · mg/dL

A waste product made when the body breaks down protein, then filtered out by the kidneys. This test measures the whole urea molecule and is the version reported by UK, EU, and Australian labs.

UnitOptimalSufficientOut of range
mmol/L3.5 – 62.5 – 7.8below 2.5 or above 7.8
mg/dL21 – 3615 – 47below 15 or above 47

Interpretation: The acceptable band is the UK harmonised laboratory interval for adults, 2.5 to 7.8 mmol/L (15 to 47 mg/dL of urea). US laboratories report urea nitrogen (BUN) instead: urea in mg/dL is 2.14 times BUN in mg/dL, so the two must not be read against each other's ranges. Urea rises with dehydration, high protein intake and reduced kidney function and falls with low protein intake, so it is read with creatinine and eGFR. The optimal band is a functional target with no published evidence behind it.

Sources

  • Urea (Pathology tests database) — University Hospitals Birmingham NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceUK harmonised adult interval (Pathology Harmony) 2.5 to 7.8 mmol/L. Exactly Sera's acceptable band.
  • Urea — North Bristol NHS Trust, Severn Pathology, 2026 · Laboratory / reference-interval sourceReference range 2.5 to 7.8 mmol/L, the same harmonised interval.

Last reviewed: November 9, 2026 · Urea on its own page

BUN (Blood Urea Nitrogen)Published reference intervalmg/dL

The nitrogen part of urea, a waste product from protein breakdown that the kidneys filter out. This is the version reported by US labs.

UnitOptimalSufficientOut of range
mg/dL10 – 166 – 20below 6 or above 20

Interpretation: The acceptable band is the general normal result given by MedlinePlus, 6 to 20 mg/dL. Laboratories differ: Mayo Clinic Laboratories reports 8 to 24 in men and 6 to 21 in women, so a result just above 20 may be printed as normal. BUN rises with dehydration, high protein intake and reduced kidney function and falls with low protein intake, so it is read with creatinine and eGFR. Outside the US the same test is reported as urea: urea in mmol/L is BUN in mg/dL multiplied by 0.357. The optimal band of 10 to 16 is a functional target with no published evidence behind it.

Sources

  • BUN - blood test — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2025 · Government / public-health guidanceNormal result is generally 6 to 20 mg/dL. Matches Sera's upper edge of 20; the lower edge is 6, not Sera's 7.
  • BUN - Overview: Blood Urea Nitrogen (BUN), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference values: men 8 to 24 mg/dL, women 6 to 21 mg/dL. Shows the interval is sex-specific at this laboratory and that upper limits above 20 are in use.

Last reviewed: November 9, 2026 · BUN on its own page

BUN:Creatinine RatioExploratory indexAuto-calculated

The ratio of blood urea nitrogen to creatinine, two waste products the kidneys clear at different rates.

Auto-calculated

BUN (mg/dL) / Creatinine (mg/dL)

Calculated when BUN (Blood Urea Nitrogen) and Creatinine are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio10 – 20—below 10 or above 20

No separate Sufficient band is currently defined for this marker.

Interpretation: A calculated ratio of urea nitrogen to creatinine, both in mg/dL. The 10 to 20 band is the figure in common use, but no guideline or laboratory reference interval for it could be verified; laboratories that print the ratio use wider limits (one reportedly 6 to 22). Read it only alongside BUN, creatinine and eGFR. It does not apply to results reported as urea in mmol/L and creatinine in umol/L.

Sources

No source is listed. This is a calculated index with no universally accepted clinical threshold to cite.

Last reviewed: November 9, 2026

Uric Acid / Creatinine RatioExploratory indexAuto-calculatedOne-sidedratio

Serum uric acid divided by serum creatinine, both in mg/dL.

Auto-calculated

Uric acid (mg/dL) / Creatinine (mg/dL)

Calculated when Uric Acid and Creatinine are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio3 – 52 – 6.5above 6.5

Bounded on the high side only — a low result is not treated as out of range. No published lower threshold exists for the serum uric acid to creatinine ratio.

Interpretation: Puts a raised uric acid in context, since urate clearance falls with kidney function and a high uric acid alongside a high creatinine may be renal rather than metabolic. Genuinely emerging: the well-validated version of this ratio is the URINARY one, a different measurement Sera does not hold, so serum thresholds are provisional. The only published threshold is from one Italian cohort, in which a ratio above 5.35 marked higher cardiovascular risk; the optimal edge here is 5. A low ratio is not flagged.

Sources

Last reviewed: November 9, 2026

Calcium (Total)Published reference intervalmg/dL · mmol/L · mEq/L

A mineral needed for strong bones, muscle function, and nerve signals. Its blood level is controlled by the kidneys and by parathyroid hormone.

UnitOptimalSufficientOut of range
mg/dL9 – 108.6 – 10.3below 8.6 or above 10.3
mmol/L2.25 – 2.52.15 – 2.58below 2.15 or above 2.58
mEq/L4.49 – 4.994.29 – 5.16below 4.29 or above 5.16

Interpretation: Total calcium tracks albumin. When albumin is abnormal, the adjusted calculation or ionised calcium is the more meaningful figure. The acceptable band follows current laboratory reference intervals: 8.6 mg/dL is the lower limit used by Mayo Clinic Laboratories and 10.3 mg/dL the upper limit given by MedlinePlus (2.20 to 2.58 mmol/L); UK laboratories use 2.20 to 2.60 mmol/L. The optimal band of 9 to 10 mg/dL is a convention with no cohort or guideline evidence behind it.

Sources

  • Calcium blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal total calcium is 8.8 to 10.3 mg/dL (2.20 to 2.58 mmol/L). This supports an upper sufficient edge of 10.3 mg/dL; Sera's 10.5 is higher and its 8.5 is lower than this interval.
  • CA - Calcium, Total, Serum — Mayo Clinic Laboratories Test Catalog, 2026 · Laboratory / reference-interval sourceAdult reference values are 8.6 to 10.0 mg/dL at 18 to 59 years and 8.8 to 10.2 mg/dL from 60 years. The 8.6 is the lowest lower limit seen and supports moving Sera's 8.5; the 10.0 coincides with Sera's optimal upper edge. Current catalogue entry, opened October 2026.
  • Calcium — Labcorp Test Directory, 2026 · Laboratory / reference-interval sourceReference interval at 18 to 59 years is 8.7 to 10.2 mg/dL for men and women; over 59 it is 8.6 to 10.2 for men and 8.7 to 10.3 for women. Confirms an upper limit of 10.2 to 10.3 mg/dL. Current directory entry, opened October 2026.

Last reviewed: November 9, 2026 · Calcium on its own page

Calcium (Adjusted)Published reference intervalmg/dL · mmol/L

Your total calcium recalculated to allow for your albumin level, because most calcium in blood travels attached to albumin. Also called corrected calcium.

UnitOptimalSufficientOut of range
mg/dL8.8 – 10.4—below 8.8 or above 10.4
mmol/L2.2 – 2.6—below 2.2 or above 2.6

No separate Sufficient band is currently defined for this marker.

Interpretation: Adjusted calcium corrects total calcium for the albumin level. The band is the reference interval UK laboratories publish for adjusted calcium, 2.20 to 2.60 mmol/L (8.8 to 10.4 mg/dL); it is a laboratory interval, not a narrower optimal target. Adjustment formulas differ between laboratories and are unreliable when albumin is very low, where ionised calcium is the better measure.

Sources

  • Calcium - Clinical Biochemistry — Oxford University Hospitals NHS Foundation Trust, 2024 · Laboratory / reference-interval sourceThe test, also known as adjusted or corrected calcium, has a reference interval of 2.20 to 2.60 mmol/L for men and women of all ages. This matches both edges of Sera's band exactly. Last reviewed 17 June 2024.
  • Calcium blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal total calcium is 8.8 to 10.3 mg/dL (2.20 to 2.58 mmol/L), which agrees with Sera's lower edge of 2.2 mmol/L (8.8 mg/dL) and sits just under its upper edge.

Last reviewed: November 9, 2026 · Adjusted calcium on its own page

Calcium (Ionised)Published reference intervalmmol/L · mg/dL

The free calcium in your blood that is not attached to albumin. This is the form your body actually uses, and it is the most accurate way to measure calcium status.

UnitOptimalSufficientOut of range
mmol/L1.15 – 1.35—below 1.15 or above 1.35
mg/dL4.6 – 5.4—below 4.6 or above 5.4

No separate Sufficient band is currently defined for this marker.

Interpretation: Ionised calcium is the free, active fraction and is not affected by albumin. The band follows published laboratory intervals: 1.15 to 1.35 mmol/L in a UK NHS laboratory and 4.57 to 5.43 mg/dL at Mayo Clinic Laboratories. Other laboratories run higher, up to 1.40 mmol/L (5.6 mg/dL), and the result depends on the analyser and on whether it is adjusted to pH 7.4, so the interval printed on the report takes precedence. It is a laboratory interval, not an optimal target.

Sources

  • CAI - Calcium, Ionized, Serum — Mayo Clinic Laboratories Test Catalog, 2026 · Laboratory / reference-interval sourceIonised calcium reference values for ages 24 to 97 are 4.57 to 5.43 mg/dL, about 1.14 to 1.36 mmol/L. This matches Sera's lower edge of 4.6 mg/dL and supports an upper edge of 5.4 mg/dL rather than 5.2. Current catalogue entry, opened October 2026.
  • Calcium (ionised) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (pathlabs.rlbuht.nhs.uk), 2026 · Laboratory / reference-interval sourceReference range 1.15 to 1.35 mmol/L. Matches Sera's lower edge of 1.15 exactly and supports an upper edge of 1.35 rather than 1.30. The page is undated and does not name the trust in its text.
  • Calcium - ionized — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceAdult ionised calcium is 4.8 to 5.6 mg/dL, or 1.20 to 1.40 mmol/L. This is a higher interval than Sera's on both sides and shows that 1.30 mmol/L is below the upper limits in mainstream use.
  • Calcium, Ionized — Labcorp Test Directory, 2026 · Laboratory / reference-interval sourceReference range 4.5 to 5.6 mg/dL. Agrees with Sera's lower edge of 4.6 mg/dL to within 0.1 and puts the upper limit at 5.6, above Sera's 5.2. Current directory entry, opened October 2026.

Last reviewed: November 9, 2026 · Ionized calcium on its own page

Magnesium (Serum)Published reference intervalmg/dL · mmol/L · mEq/L

The amount of magnesium in your blood serum. Any excess is removed by the kidneys.

UnitOptimalSufficientOut of range
mg/dL2.07 – 2.31.7 – 2.4below 1.7 or above 2.4
mmol/L0.85 – 0.950.7 – 1below 0.7 or above 1
mEq/L1.7 – 1.91.4 – 2below 1.4 or above 2

Interpretation: The acceptable band follows laboratory reference intervals: 1.7 mg/dL (0.70 mmol/L) is the lower limit used by MedlinePlus, Mayo Clinic Laboratories and UK laboratories, and 1.0 mmol/L (2.4 mg/dL) is the UK upper limit; US laboratories stop at 2.2 to 2.3 mg/dL. The optimal band starts at 0.85 mmol/L (2.07 mg/dL), the lower limit a group of magnesium researchers recommended in 2022 on the grounds that lower values can hide a chronic deficit; few laboratories have adopted it. Serum magnesium is a rough guide to body stores and can be normal when stores are low.

Sources

  • Magnesium blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal blood magnesium is 1.7 to 2.2 mg/dL (0.70 to 0.91 mmol/L). Matches Sera's sufficient lower edge of 1.7 mg/dL exactly; its upper limit of 2.2 is well under Sera's 2.6.
  • MGS - Magnesium, Serum — Mayo Clinic Laboratories Test Catalog, 2026 · Laboratory / reference-interval sourceReference values over 17 years are 1.7 to 2.3 mg/dL. Matches Sera's sufficient lower edge of 1.7; the 2.3 upper limit equals Sera's optimal upper edge and is below its sufficient upper edge of 2.6. Current catalogue entry, opened October 2026.
  • Magnesium — Worcestershire Acute Hospitals NHS Trust, Pathology tests A to Z, 2026 · Laboratory / reference-interval sourceReference range from 30 days of age is 0.7 to 1.0 mmol/L, attributed to the UK Pathology Harmony ranges. Supports the 0.70 mmol/L lower edge and an upper edge of 1.00 mmol/L (2.4 mg/dL) in place of Sera's 1.05 (2.6 mg/dL). The page is undated.
  • Recommendation on an updated standardization of serum magnesium reference ranges — Rosanoff A, West C, Elin RJ, et al. — European Journal of Nutrition, 2022 · Peer-reviewed publicationRecommends 0.85 mmol/L (2.07 mg/dL; 1.7 mEq/L) as the lower reference limit for serum magnesium, to avoid counting people with chronic latent magnesium deficit as normal. Only 2 of 43 laboratory ranges surveyed used it. Sera's optimal lower edge of 2.0 mg/dL (0.82 mmol/L) is close but lower.

Last reviewed: November 9, 2026 · Serum magnesium on its own page

Magnesium (RBC)Functional / longevity targetAssay-dependentmg/dL · mmol/L

Magnesium measured inside your red blood cells, which is more accurate than the serum test.

UnitOptimalSufficientOut of range
mg/dL5.5 – 6.84.2 – 7.5below 4.2 or above 7.5
mmol/L2.3 – 2.651.65 – 3.05below 1.65 or above 3.05

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Only one laboratory interval could be confirmed, Labcorp's 3.7 to 7.0 mg/dL, and Sera's acceptable band of 4.2 to 7.5 does not match it. The optimal band of 5.5 to 6.8 is a functional-practice convention with no primary source. Red cell magnesium is offered by few laboratories, and at least one large one has withdrawn it.

Sources

  • Magnesium, RBC — Labcorp Test Directory, 2026 · Laboratory / reference-interval sourceReference interval for red-cell magnesium is 3.7 to 7.0 mg/dL. Sera's sufficient band of 4.2 to 7.5 differs on both sides. Current directory entry, opened October 2026.

Last reviewed: November 9, 2026 · RBC magnesium on its own page

PhosphatePublished reference intervalmg/dL · mmol/L

A mineral that travels in the blood as phosphate and is needed for building bone, making energy, and forming cell membranes. Its level is controlled by the kidneys alongside calcium and parathyroid hormone. Phosphorus and phosphate refer to the same blood test.

UnitOptimalSufficientOut of range
mg/dL3 – 42.5 – 4.5below 2.5 or above 4.5
mmol/L0.97 – 1.290.81 – 1.45below 0.81 or above 1.45

Interpretation: The acceptable band is the adult reference interval used by Mayo Clinic Laboratories, 2.5 to 4.5 mg/dL; UK laboratories use 0.8 to 1.5 mmol/L. The optimal band of 3 to 4 mg/dL is a functional convention: cohort studies link higher phosphate to cardiovascular risk, but no published threshold for it was verified. Phosphate rises after meals and varies through the day, so a fasting morning sample is the most comparable.

Sources

  • PHOS - Phosphorus (Inorganic), Serum — Mayo Clinic Laboratories Test Catalog, 2026 · Laboratory / reference-interval sourceReference values from 18 years are 2.5 to 4.5 mg/dL in both men and women. Matches both edges of Sera's sufficient band exactly. Current catalogue entry, opened October 2026.
  • Phosphorus blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal adult phosphorus is 2.8 to 4.5 mg/dL. Matches Sera's sufficient upper edge of 4.5 exactly; the lower limit is 0.3 above Sera's 2.5.
  • Phosphate — University Hospitals of North Midlands NHS Trust, Pathology, 2018 · Laboratory / reference-interval sourceAdult (over 16 years) reference range is 0.8 to 1.5 mmol/L, derived from Pathology Harmony 2011 and approved by the trust's biochemists in 2018. Agrees with Sera's mmol/L row of 0.81 to 1.45.
  • Phosphorus — Labcorp Test Directory, 2026 · Laboratory / reference-interval sourceReference interval over 19 years is 2.8 to 4.1 mg/dL in men and 3.0 to 4.3 in women, from Labcorp internal studies. A narrower laboratory interval that sits near Sera's optimal band of 3 to 4 but is not evidence for an optimal target. Current directory entry, opened October 2026.

Last reviewed: November 9, 2026 · Phosphate on its own page

Bicarbonate (CO2 / Total CO2)Published reference intervalmmol/L · mEq/L

The blood's main buffer against acid, managed by the kidneys and lungs together. On US and Gulf panels it is usually printed as CO2 or Total CO2, which means this test and nothing respiratory.

UnitOptimalSufficientOut of range
mmol/L22 – 29—below 22 or above 29
mEq/L22 – 29—below 22 or above 29

No separate Sufficient band is currently defined for this marker.

Interpretation: Reported as bicarbonate or total CO2; the two are used interchangeably on a metabolic panel. The band is the adult laboratory reference interval, 22 to 29 mmol/L, used by Mayo Clinic Laboratories and by UK laboratories; it is not a narrower optimal target. Lower limits differ between laboratories (20 at Labcorp, 23 on MedlinePlus), so a result of 20 to 22 may be in range on the report. A sample that waits before analysis loses CO2 and reads falsely low.

Sources

  • HCO3 - Bicarbonate, Serum — Mayo Clinic Laboratories Test Catalog, 2026 · Laboratory / reference-interval sourceReference values are 22 to 29 mmol/L for men from 18 years and women from 10 years. Matches both edges of Sera's band exactly. Current catalogue entry, opened October 2026.
  • Bicarbonate — Worcestershire Acute Hospitals NHS Trust, Pathology tests A to Z, 2026 · Laboratory / reference-interval sourceReference range over 16 years is 22 to 29 mmol/L, attributed to the UK Pathology Harmony ranges. Matches both edges of Sera's band exactly. The page is undated.
  • CO2 blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal range is 23 to 29 mEq/L, the same in mmol/L. Matches Sera's upper edge of 29 exactly; the lower limit is 1 above Sera's 22.
  • Carbon Dioxide, Total — Labcorp Test Directory, 2026 · Laboratory / reference-interval sourceRange over 12 years is 20 to 29 mmol/L. Matches Sera's upper edge of 29; the lower limit is 2 below Sera's 22, so a result of 20 or 21 may be printed as normal on a Labcorp report. Current directory entry, opened October 2026.

Last reviewed: November 9, 2026 · Bicarbonate (CO2) on its own page

Thyroid Health · 18 markers

Core markers for evaluating thyroid function and autoimmunity

TSH (Thyroid-Stimulating Hormone)Published reference intervalmIU/L · μIU/mL

A hormone made by the pituitary gland in your brain that tells the thyroid how much hormone to produce.

UnitOptimalSufficientOut of range
mIU/L0.5 – 20.5 – 4.5below 0.5 or above 4.5
μIU/mL0.5 – 20.5 – 4.5below 0.5 or above 4.5

Interpretation: The acceptable band is the traditional TSH reference range of 0.5 to 4.5 mIU/L, as the American Thyroid Association describes it. Laboratories print slightly different limits for their own assay, from about 0.3 to 0.45 at the bottom and 4.2 to 5.3 at the top, so check a borderline result against the issuing laboratory's interval. The narrower optimal band ending at 2 is a functional target with no guideline behind it; in pooled cohort data on 134,000 adults the lowest cardiovascular and mortality risk sat at a TSH of roughly 1.9 to 2.9, not below 2. TSH also follows a daily rhythm, running highest overnight and early morning.

Sources

Last reviewed: November 9, 2026 · TSH on its own page

Free T4 (FT4)Published reference intervalAssay-dependentng/dL · pmol/L

The free, active form of thyroxine that is available for your cells to use.

UnitOptimalSufficientOut of range
ng/dL1.1 – 1.50.9 – 1.8below 0.9 or above 1.8
pmol/L14 – 1912 – 23below 12 or above 23

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The acceptable band follows US laboratory reference intervals for adults (Mayo 0.9 to 1.7 ng/dL, Labcorp 0.82 to 1.77). Assay-dependent: intervals differ between platforms, and UK laboratories on Beckman assays report 8.0 to 18.0 pmol/L, so compare against the issuing laboratory's own interval before acting on a borderline value. The optimal band is a functional target with no published threshold behind it; pooled cohort data found the lowest cardiovascular and mortality risk in the low-normal part of the range, around 13.5 to 14.8 pmol/L, rather than the upper half.

Sources

Last reviewed: November 9, 2026 · Free T4 on its own page

Free T3 (FT3)Published reference intervalAssay-dependentpg/mL · pmol/L

The most active thyroid hormone, which directly drives your metabolism.

UnitOptimalSufficientOut of range
pg/mL3.2 – 4.22.5 – 4.5below 2.5 or above 4.5
pmol/L4.9 – 6.53.8 – 6.9below 3.8 or above 6.9

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The acceptable band sits within published adult laboratory intervals (Labcorp 2.0 to 4.4 pg/mL; UK laboratories 3.7 or 3.8 to 6.0 or 6.6 pmol/L). Assay-dependent: intervals differ between platforms, and some laboratories set the lower limit at 2.0 pg/mL, so compare against the issuing laboratory's own interval before acting on a borderline value. The optimal band is a functional target with no published threshold behind it.

Sources

  • Triiodothyronine (T3), Free — Labcorp, 2026 · Laboratory / reference-interval sourceAdult interval of 2.0 to 4.4 pg/mL. Supports Sera's upper edge of 4.5 after rounding; the lower limit is 2.0 against Sera's 2.5.
  • Free T3 — Worcestershire Acute Hospitals NHS Trust, 2026 · Laboratory / reference-interval sourceAdult interval of 3.8 to 6.0 pmol/L for men and women on a Beckman Coulter assay. The lower limit equals Sera's 3.8 pmol/L; the upper limit is below Sera's 6.9.
  • Thyroid Function Tests — North Bristol NHS Trust, Severn Pathology, 2026 · Laboratory / reference-interval sourceFree T3 interval of 3.7 to 6.6 pmol/L, close to Sera's 3.8 to 6.9 pmol/L.

Last reviewed: November 9, 2026 · Free T3 on its own page

Free T3 / Free T4 RatioExploratory indexAuto-calculatedratio

Free T3 divided by free T4, both expressed in pmol/L.

Auto-calculated

Free T3 (pmol/L) / Free T4 (pmol/L)

Calculated when Free T3 (FT3) and Free T4 (FT4) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio0.3 – 0.50.2 – 0.6below 0.2 or above 0.6

Interpretation: A read on conversion rather than production, so a low ratio with a normal TSH is the picture functional practice calls poor conversion. There is no accepted threshold for this ratio. One European laboratory study put the central 95% of results at 0.21 to 0.47, and in US survey data a higher ratio went with lower mortality, without a cut-off. The bands here are functional targets, and because free T3 and free T4 intervals differ between assays the ratio does too. Sera normalises both hormones to pmol/L before dividing — leaving one side in ng/dL would change the answer by more than an order of magnitude, and the band assumes the molar form.

Sources

Last reviewed: November 9, 2026

ATPO (Anti-Thyroid Peroxidase Antibodies)Published reference intervalIU/mL · kIU/L

Antibodies that attack thyroid peroxidase, an enzyme the thyroid needs to make its hormones.

UnitOptimalSufficientOut of range
IU/mL0 – 99 – 34below 0 or above 34
kIU/L0 – 99 – 34below 0 or above 34

Interpretation: Read this one against the cut-off printed on the report: the two edges here are two manufacturers' positivity cut-offs, not grades of severity. Laboratories on Beckman Coulter assays report positive from 9 IU/mL (Mayo, Worcestershire NHS), Labcorp's adult range runs to 34 IU/mL, and UK laboratories on the newer Roche kit use 20. So a result between 9 and 34 shows here as Sufficient and may be positive on the assay that produced it. A positive result marks thyroid autoimmunity and is the usual antibody finding in Hashimoto's thyroiditis; the number itself is not comparable between laboratories.

Sources

  • TPO - Overview: Thyroperoxidase Antibodies, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference value below 9.0 IU/mL at all ages. This is where Sera's optimal band ends, but Mayo treats 9 and above as positive, not as a second acceptable tier.
  • Thyroid Peroxidase Abs — Worcestershire Acute Hospitals NHS Trust, 2026 · Laboratory / reference-interval sourceReference range below 9 IU/mL, sourced to Beckman Coulter. Confirms that 9 is the Beckman assay's cut-off.
  • Thyroid Peroxidase (TPO) Antibodies — Labcorp, 2026 · Laboratory / reference-interval sourceAdult range of 0 to 34 IU/mL by electrochemiluminescence immunoassay. This is Sera's acceptable upper edge of 34.
  • TPO antibody — University Hospitals Sussex NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceReference range below 20 IU/mL from the Roche Cobas Anti-TPO II kit insert, changed on 5 October 2026 with a method change. Shows the Roche cut-off is no longer 34 on the newer kit.
  • Thyroid Peroxidase Antibodies — York and Scarborough Teaching Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceReference interval below 20 IU/mL, quoted by the manufacturer. A second UK laboratory using 20 rather than 34.

Last reviewed: November 9, 2026 · TPO antibodies on its own page

ATG (Anti-Thyroglobulin Antibodies)Published reference intervalIU/mL · kIU/L

Antibodies that attack thyroglobulin, a protein stored inside the thyroid.

UnitOptimalSufficientOut of range
IU/mL0 – 4—below 0 or above 4
kIU/L0 – 4—below 0 or above 4

No separate Sufficient band is currently defined for this marker.

Interpretation: The band ends at 4 IU/mL, the positivity cut-off several widely used assays share (Mayo below 4.0, Abbott-based NHS laboratories below 4.11, Labcorp's upper reference limit below 4). It is not universal: other platforms use much higher numbers, so where the report prints a different cut-off, that one applies. Thyroglobulin antibodies also interfere with thyroglobulin measurement, which matters when thyroglobulin is used for thyroid cancer follow-up.

Sources

  • TGAB - Overview: Thyroglobulin Antibody, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference value below 4.0 IU/mL at all ages. Matches Sera's optimal upper edge of 4, as a positivity cut-off.
  • Anti-Thyroglobulin Antibodies — University Hospitals Birmingham NHS Foundation Trust, 2026 · Laboratory / reference-interval sourcePositive at 4.11 or above and negative below 4.11, sourced to Abbott Diagnostics; the page prints the unit as IU/L. Close to Sera's edge of 4. Page last updated 19 August 2026.
  • Thyroglobulin Antibody — Labcorp, 2026 · Laboratory / reference-interval sourceIn 137 screened samples the 95% upper reference limit was below 4 IU/mL, and Labcorp reports any result above its limit of detection as elevated. Supports 4 as the top of normal and gives no support for an acceptable tier above it.

Last reviewed: November 9, 2026 · Thyroglobulin antibodies on its own page

Thyroglobulin (Tg)No universal rangeUnbandedng/mL · μg/L · unbanded

The protein the thyroid stores its hormone in. Not the antibody against it, which is a separate test.

No universal Sera range published.

Limits depend on whether the thyroid is intact or removed, and on the assay, and the result cannot be read without antibody status. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Thyroglobulin is the protein the thyroid stores its hormone in, not the antibody against it. Its main use is follow-up after treatment for differentiated thyroid cancer, where the aim is a level that is very low or undetectable and the trend over time matters more than any single result. It is not used to diagnose thyroid cancer. Read it only with thyroglobulin antibody status: antibodies, common in Hashimoto's, can make the result falsely low. Normal limits depend on whether the thyroid is intact, partly removed or removed, and on the assay, from below 20 to 60 μg/L in an intact gland, so Sera records the number and leaves the reading to the laboratory's range and the treating team. 1 ng/mL equals 1 μg/L.

Sources

  • Thyroglobulin — MedlinePlus, US National Library of Medicine, 2026 · Government / public-health guidanceStates that thyroglobulin is used to monitor known thyroid cancer, not to diagnose it, and that an antibody test is usually ordered first because thyroglobulin antibodies make the result unreliable. Updated January 2026.
  • Thyroglobulin — Exeter Clinical Laboratory International, Royal Devon University Healthcare NHS Foundation Trust, 2023 · Laboratory / reference-interval sourceNHS laboratory offering the test for monitoring thyroid carcinoma, with limits set by treatment status: untreated up to 60 μg/L, partial thyroidectomy up to 10, total thyroidectomy up to 3. Thyroglobulin antibodies are run with every request.
  • Thyroglobulin by LC-MS/MS, Serum or Plasma (test 2006550) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) interval 1.3 to 31.8 ng/mL by mass spectrometry, the method recommended when thyroglobulin antibodies are present. Compare 60 μg/L at Exeter and below 20 ng/mL in the ABIM table.
  • ABIM Laboratory Test Reference Ranges, January 2026 — American Board of Internal Medicine, 2026 · Laboratory / reference-interval sourceUS reference table: serum thyroglobulin below 20 ng/mL.

Last reviewed: November 9, 2026

TRAb / TSI (TSH Receptor Antibodies)Published reference intervalAssay-dependentIU/L · U/L

Antibodies against the TSH receptor, which in Graves' disease stimulate the thyroid rather than block it.

UnitOptimalSufficientOut of range
IU/L0 – 1.75—below 0 or above 1.75
U/L0 – 1.75—below 0 or above 1.75

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The test that separates Graves' disease from the other causes of thyrotoxicosis, which matters because the treatments diverge. It also crosses the placenta, so a level in a pregnant woman with current or past Graves' disease changes fetal monitoring; the European Thyroid Association advises monitoring the fetus when the level stays above 3 times the assay cut-off. TRAb measures binding and TSI measures stimulation — different assays on different scales, reported under names that are used interchangeably. The band here is the TRAb binding-assay cut-off of 1.75 IU/L used by Labcorp and Mayo. A TSI result has its own cut-off, 0.55 IU/L at the same laboratories, and should be read against the report, not this band.

Sources

  • Thyrotropin Receptor Antibody, Serum — Labcorp, 2026 · Laboratory / reference-interval sourceReference interval of 0.0 to 1.75 units/L by electrochemiluminescence immunoassay. Sera's acceptable band ends at 2, above this cut-off.
  • THYRO - Overview: Thyrotropin Receptor Antibody, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference value of 1.75 IU/L or below. A second laboratory with the same cut-off.
  • Thyroid-stimulating Immunoglobulin (TSI) — Labcorp, 2026 · Laboratory / reference-interval sourceTSI reference interval of 0.00 to 0.55 IU/L; at that cut-off sensitivity for Graves' disease was 98.6% and specificity 98.5%. A TSI result cannot be scored on the TRAb band.
  • FFTSI - Overview: Thyroid-stimulating Immunoglobulin (TSI) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceTSI reference value of 0.00 to 0.55 IU/L, the same cut-off Labcorp prints.
  • 2018 European Thyroid Association Guideline for the Management of Graves' Hyperthyroidism — Kahaly GJ, Bartalena L, Hegedüs L, et al. — European Thyroid Journal (European Thyroid Association), 2018 · Professional societyRecommends TSH receptor antibody measurement for diagnosis and in pregnancy, and expresses its one threshold as more than 3 times the assay cut-off rather than as a number. Supports reading the result against the assay's own cut-off, and the pregnancy point in Sera's note.

Last reviewed: November 9, 2026 · TRAb on its own page

Total T4Published reference intervalAssay-dependentμg/dL · nmol/L · ng/dL

The total amount of T4 in your blood, both the bound and the free forms.

UnitOptimalSufficientOut of range
μg/dL6 – 104.5 – 12below 4.5 or above 12
nmol/L77 – 12958 – 154below 58 or above 154
ng/dL6,000 – 10,0004,500 – 12,000below 4,500 or above 12,000

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The acceptable band of 4.5 to 12 µg/dL is the adult laboratory reference interval for total T4 (Labcorp 4.5 to 12.0; Mayo Clinic Laboratories 4.5 to 11.7). The optimal band of 6 to 10 µg/dL is a functional target with no published study or guideline behind it. Total T4 follows binding proteins: pregnancy and oestrogen raise it without any change in thyroid function, so read it alongside TSH and free T4. Intervals vary by assay; the laboratory's own interval takes precedence.

Sources

  • Thyroxine (T4) — Labcorp, 2026 · Laboratory / reference-interval sourceReference interval 4.5 to 12.0 µg/dL by electrochemiluminescence immunoassay. This is Sera's sufficient band exactly.
  • T4 (Thyroxine), Total Only, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference values (20 years and older) 4.5 to 11.7 µg/dL by electrochemiluminescence immunoassay. Matches Sera's lower edge of 4.5 exactly; the upper edge is 0.3 µg/dL below Sera's 12.

Last reviewed: November 9, 2026 · Total T4 on its own page

T3 UptakePublished reference interval%

An estimate of how many free binding sites thyroid-binding proteins have, used to correct total T4 for binding. Not a measure of T3.

UnitOptimalSufficientOut of range
%24 – 39—below 24 or above 39

No separate Sufficient band is currently defined for this marker.

Interpretation: T3 uptake is not a measure of T3. It estimates how many free binding sites the carrier proteins (mainly thyroxine-binding globulin) have, and its use is to correct total T4 for binding, which gives the free thyroxine index. The band is 24 to 39 %, Labcorp's adult interval, or 0.8 to 1.3 where the laboratory reports it as a binding ratio. A low uptake usually means more binding protein, as with oestrogen, the pill or pregnancy, and a high uptake means less, as with androgens, high-dose steroids or protein loss. It is not read alone. Free T4 measured directly has largely replaced it, and it is mainly seen on older thyroid panels. Biotin supplements can distort the result.

Sources

  • T3 Uptake (test 001156) — Labcorp test directory, 2026 · Laboratory / reference-interval sourceAdult (over 18) interval 24 to 39 % for men and women. The test reflects available binding sites on thyroxine-binding globulin, is not a measurement of serum T3, and is used with total T4 to give the free T4 index.
  • ABIM Laboratory Test Reference Ranges, January 2026 — American Board of Internal Medicine, 2026 · Laboratory / reference-interval sourceUS reference table: T3 resin uptake 25 to 35 %. Narrower than Labcorp's, cited as a comparison.
  • Thyroxine (T4), Uptake, Serum (test TUP) — NorDx Laboratories (MaineHealth), 2026 · Laboratory / reference-interval sourceRoche electrochemiluminescence assay reported as a binding ratio: reference values 0.8 to 1.3 TBI. Biotin falsely raises the result.
  • T Uptake (Thyroxine Binding Capacity) (test 918) — Northwell Health Laboratories, 2026 · Laboratory / reference-interval sourceSame assay family, reported both ways: ratio 0.8 to 1.3 TBI units and percent 28 to 41 %.

Last reviewed: November 9, 2026 · T3 Uptake on its own page

Free Thyroxine Index (FTI)Published reference interval

Total T4 corrected for binding proteins using T3 uptake, calculated by the laboratory.

UnitOptimalSufficientOut of range
ratio1.2 – 4.9—below 1.2 or above 4.9

No separate Sufficient band is currently defined for this marker.

Interpretation: The free thyroxine index is calculated by the laboratory from total T4 and T3 uptake. It estimates free T4 by correcting total T4 for binding proteins, and it is now largely replaced by free T4 measured directly. The band is 1.2 to 4.9, Labcorp's interval, where the index is total T4 times percent uptake. Laboratories that use a binding ratio instead print numbers on the T4 scale, about 4.4 to 11.4, so check which scale the report uses before reading a result. Read it with TSH. It is not reliable when binding proteins are very abnormal, in pregnancy or during acute illness.

Sources

  • Thyroid Panel sample report (test 000455) — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp's sample report for the thyroid panel prints total T4 4.5 to 12.0 μg/dL, T3 uptake 24 to 39 % and free thyroxine index 1.2 to 4.9. Matches the Labcorp-scale row.
  • Thyroid Profile (test 000455) — Labcorp test directory, 2026 · Laboratory / reference-interval sourceDirectory entry for the panel: describes the free thyroxine index as an index correlating with free T4. No numbers on the page.
  • T Uptake (Thyroxine Binding Capacity) (test 918) — Northwell Health Laboratories, 2026 · Laboratory / reference-interval sourcePrints both scales: FTI 4.4 to 11.4 (from the binding ratio) and percent FTI 1.4 to 4.8 (from percent uptake), and calculates the index when T4 is also ordered.
  • ABIM Laboratory Test Reference Ranges, January 2026 — American Board of Internal Medicine, 2026 · Laboratory / reference-interval sourceUS reference table: free thyroxine index (estimate) 5 to 12, on the ratio scale.

Last reviewed: November 9, 2026 · Free thyroxine index on its own page

Thyroxine-Binding Globulin (TBG)Published reference intervalSex-specificμg/mL · mg/L

The main protein that carries thyroid hormone in the blood.

UnitApplies toOptimalSufficientOut of range
μg/mLMale12 – 26—below 12 or above 26
μg/mLFemale11 – 27—below 11 or above 27
mg/LMale12 – 26—below 12 or above 26
mg/LFemale11 – 27—below 11 or above 27

No separate Sufficient band is currently defined for this marker.

Interpretation: The bands are Mayo Clinic Laboratories' adult intervals: 12 to 26 μg/mL for men and 11 to 27 for women. μg/mL and mg/L are the same number. A Dutch hospital laboratory (analysed at Erasmus MC) agrees for men but gives women up to 38 mg/L, most likely because its population includes women on oestrogen, which raises TBG. TBG explains a total T4 or T3 that disagrees with the free hormone and is not a target in itself, so there is no optimal range. No NHS trust publishes an interval; UK samples are usually sent away.

Sources

  • Thyroxine-Binding Globulin (TBG), Serum (TBGI) — Mayo Clinic Laboratories (performing laboratory), Duke University Hospital test catalog, 2026 · Laboratory / reference-interval sourceAdult intervals: men 12 to 26 μg/mL, women 11 to 27 μg/mL. The basis of Sera's bands.
  • K-VZ TBG (Thyroxine-binding globulin) - Labgids — Ziekenhuis Slingeland (Netherlands), analysed at Erasmus MC, 2017 · Laboratory / reference-interval sourceEuropean intervals: men 12 to 23 mg/L, women 14 to 38 mg/L. Confirms the sex split and the male low edge; women's upper edge is much higher than Mayo's.

Last reviewed: November 9, 2026 · TBG on its own page

Total T3Published reference intervalAssay-dependentng/dL · nmol/L · pg/mL

The total amount of T3 in your blood, both the bound and the free forms.

UnitOptimalSufficientOut of range
ng/dL100 – 18080 – 200below 80 or above 200
nmol/L1.5 – 2.81.2 – 3.1below 1.2 or above 3.1
pg/mL1,000 – 1,800800 – 2,000below 800 or above 2,000

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The acceptable band of 80 to 200 ng/dL is the adult reference interval of Mayo Clinic Laboratories. Intervals differ by assay: Labcorp reports 71 to 180 ng/dL, so the laboratory's own interval takes precedence. The optimal band of 100 to 180 ng/dL is a functional target with no published study or guideline behind it. Total T3 follows binding proteins and is not a reliable marker of hypothyroidism; it falls in illness and with amiodarone.

Sources

  • T3 (Triiodothyronine), Total, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference values (20 years and older) 80 to 200 ng/dL; values above 200 ng/dL in adults are described as consistent with hyperthyroidism or raised binding proteins. This is Sera's sufficient band exactly.
  • Triiodothyronine (T3) — Labcorp, 2026 · Laboratory / reference-interval sourceReference range for ages over 10 years 71 to 180 ng/dL by electrochemiluminescence immunoassay. Shows the interval is assay-dependent: both edges sit below Sera's 80 and 200.

Last reviewed: November 9, 2026 · Total T3 on its own page

Reverse T3 (rT3)No universal rangeUnbandedAssay-dependentng/dL · ng/mL · pmol/L · nmol/L · unbanded

An inactive version of T3 that sits on T3 receptors and blocks the active hormone.

No universal Sera range published.

Assay methods disagree by more than threefold and the intervals do not overlap. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Sera publishes no band for reverse T3. Laboratories that measure it by mass spectrometry report an adult interval of about 10 to 24 ng/dL (Mayo Clinic Laboratories 10 to 24; Labcorp 9.2 to 24.1), but laboratories using other methods print intervals several times higher, so no single band is right for every report. No professional guideline recommends the test or sets a threshold for it. Read the result against the interval printed on the report. A raised value alongside a low T3 in someone who is unwell fits non-thyroidal illness.

Sources

  • T3 (Triiodothyronine), Reverse, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference values 10 to 24 ng/dL by LC-MS/MS; to convert ng/dL to nmol/L multiply by 0.01536. A raised value in a sick patient with low T3 is consistent with sick euthyroid syndrome. No band in Sera; this is the LC-MS/MS interval for context.
  • Reverse T3 — Labcorp, 2026 · Laboratory / reference-interval sourceReference interval for ages 16 and older 9.2 to 24.1 ng/dL by LC/MS-MS. Agrees with Mayo's interval on the same method.
  • Trust your Endocrinologist - Report and Recommendations on the Ordering of Reverse T3 Testing — Garnett ER, Pagaduan JV, Devaraj S — Annals of Clinical and Laboratory Science, 2020 · Peer-reviewed publicationA US hospital laboratory audit: reverse T3 testing is not recommended by any professional practice guideline, and 11 of 20 orders reviewed were inappropriate. Supports publishing no target.

Last reviewed: November 9, 2026

Free T3 / Reverse T3 RatioNo universal rangeAuto-calculatedUnbandedratio · unbanded

Free T3 divided by reverse T3, both expressed in pmol/L.

Auto-calculated

Free T3 (pmol/L) / Reverse T3 (pmol/L)

Calculated when Free T3 (FT3) and Reverse T3 (rT3) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

Built on reverse T3, whose assays disagree by more than threefold, so the ratio is not comparable between laboratories. Read this marker against the interval printed by the issuing laboratory.

Sources

Last reviewed: November 9, 2026

Selenium (Serum)Published reference intervalAssay-dependentμg/L · ng/mL · μmol/L

Serum or plasma selenium, the circulating fraction — distinct from the red cell compartment, which reflects a longer window.

UnitOptimalSufficientOut of range
μg/L110 – 15090 – 200below 90 or above 200
ng/mL110 – 15090 – 200below 90 or above 200
μmol/L1.4 – 1.91.14 – 2.5below 1.14 or above 2.5

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The acceptable band of 90 to 200 µg/L follows the adult laboratory reference interval (Labcorp 93 to 198 µg/L); the NIH Office of Dietary Supplements regards 80 µg/L or higher as usually sufficient. The optimal band of 110 to 150 µg/L is a functional target: 110 is the lower limit of Mayo Clinic Laboratories' adult interval (110 to 165), and in a Swedish trial selenoprotein P was fully saturated at a serum selenium of 146 µg/L, so higher levels add no further selenoprotein. No outcome study sets 150 as a ceiling. Serum selenium reflects recent intake and falls with inflammation.

Sources

  • Selenium, Serum or Plasma — Labcorp, 2026 · Laboratory / reference-interval sourceAdult (over 18 years) reference interval 93 to 198 µg/L for both sexes by ICP-MS; environmental exposure range 79 to 326 µg/L. Close to Sera's sufficient band of 90 to 200.
  • Selenium, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceNormal adult serum selenium 110 to 165 µg/L; in deficiency with loss of glutathione peroxidase activity the serum level is usually below 40 µg/L. The lower limit of 110 matches Sera's optimal lower edge.
  • Selenium - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2025 · Government / public-health guidancePlasma or serum selenium of 8 µg/dL (80 µg/L) or higher is usually considered sufficient in healthy people. This sits 10 µg/L below Sera's sufficient lower edge of 90.
  • Selenoprotein P increases upon selenium and coenzyme Q10 supplementation and is associated with telomere length, quality of life and reduced inflammation and mortality — Alehagen U, et al. — Free Radical Biology & Medicine, 2024 · Peer-reviewed publicationIn an elderly Swedish supplementation trial, selenoprotein P reached saturation at a serum selenium of 146 µg/L and glutathione peroxidase 3 at 99 µg/L. Close to Sera's optimal upper edge of 150; a biomarker plateau, not an outcome threshold.

Last reviewed: November 9, 2026 · Serum selenium on its own page

Selenium (RBC)Functional / longevity targetAssay-dependentng/mL · μg/L · μmol/L

Erythrocyte selenium, the intracellular fraction. Red cells take up selenium only while they are being made, so this reflects status over the 120-day lifespan of the cell rather than the last few weeks.

UnitOptimalSufficientOut of range
ng/mL120 – 18080 – 220below 80 or above 220
μg/L120 – 18080 – 220below 80 or above 220
μmol/L1.52 – 2.281.01 – 2.79below 1.01 or above 2.79

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Red cells take up selenium only while they are being made, so this reads the last 120 days where the serum value reads the last few weeks and moves with inflammation. The bands sit ABOVE the serum ones because red cells concentrate selenium. The optimal band is Sera's own derivation and not a published interval: the serum functional target (110–150 ng/mL) multiplied by an assumed RBC:serum ratio of 1.2 to 1.6, for which no published source was found. The one mainstream laboratory interval for red cell selenium is Quest Diagnostics' 120 to 300 μg/L, and the acceptable band here (80 to 220) does not match it: a result of 80 to 119 reads Sufficient here though it is below that laboratory's lower limit, and 221 to 300 reads Out of range though the laboratory calls it normal. Whole blood is a different measurement and is not mapped onto these bands.

Sources

  • Selenium, RBC — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceReference range 120 to 300 µg/L for red-cell selenium by ICP-MS (test code 17133). The lower limit matches Sera's optimal lower edge of 120; it is 40 above Sera's sufficient lower edge of 80 and the upper limit is 80 above Sera's 220.
  • Selenium, Blood — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceWhole-blood selenium reference values for adults 150 to 241 ng/mL. Context only: whole blood is a different specimen, and this interval does not match the 80 to 220 that Sera's note says the sufficient band was aligned with.

Last reviewed: November 9, 2026 · RBC selenium on its own page

IodineSera practitioner target — source review pendingAssay-dependentμg/L · μg/dL

Iodine measured in blood. Iodine is a building block the thyroid needs to make its hormones, and serum levels reflect your intake over the past hours to days.

UnitOptimalSufficientOut of range
μg/L60 – 15045 – 250below 45 or above 250
μg/dL6 – 154.5 – 25below 4.5 or above 25

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Laboratories disagree, and Sera's bands match none of them: Mayo gives 40 to 92 μg/L and Labcorp 31 to 65. Mayo treats values above 250, the upper edge of the acceptable band here, as possible iodine overload. Read the result against the range on the report. Urinary iodine, not serum, is the usual measure of iodine status.

Sources

  • Iodine, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference values 40 to 92 ng/mL by ICP-MS. Values of 80 to 250 ng/mL have been reported in hyperthyroidism and values above 250 ng/mL may indicate iodine overload. Sera's sufficient upper edge of 250 is this overload figure, not the reference limit.
  • Iodine, Serum or Plasma — Labcorp, 2026 · Laboratory / reference-interval sourceReference interval for ages 6 to 70 years 31.1 to 64.6 µg/L for both sexes by ICP-MS. Lower than Mayo's 40 to 92, which shows the interval is laboratory-specific; both end far below Sera's 250.
  • Iodine - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2024 · Government / public-health guidanceIodine status is typically assessed with urinary iodine; median urinary concentrations of 100 to 199 µg/L indicate adequate intake in adults. The page gives no serum threshold, so no public-health figure supports a serum band.

Last reviewed: November 9, 2026

Hormone Health · 20 markers

Adrenal and sex hormones that affect energy, mood, and metabolism

Testosterone (Total)Established clinical thresholdSex-specificCycle-dependentAssay-dependentng/dL · nmol/L · ng/mL

The total amount of testosterone in your blood, including both the bound and free forms.

UnitApplies toOptimalSufficientOut of range
ng/dLFemale40 – 608 – 60below 8 or above 60
ng/dLMale500 – 900300 – 916below 300 or above 916
nmol/LFemale1.4 – 2.10.28 – 2.1below 0.28 or above 2.1
nmol/LMale17.3 – 31.210.4 – 31.8below 10.4 or above 31.8
ng/mLFemale0.4 – 0.60.08 – 0.6below 0.08 or above 0.6
ng/mLMale5 – 93 – 9.16below 3 or above 9.16

Cycle: Female range spans the cycle, peaking around ovulation.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: For men, the acceptable band starts at 300 ng/dL (10.4 nmol/L), the American Urological Association cut-off for low testosterone, and ends at 916 ng/dL, the top of the harmonised reference range for healthy men aged 19 to 39 used by the Endocrine Society. European urology guidance uses a slightly higher cut-off of 12 nmol/L. The optimal band of 500 to 900 ng/dL is a functional target: the AUA aims for the middle of the range in men on therapy, and no outcome study shows that an untreated man does better at 500 than at 350. For women, the band of 8 to 60 ng/dL is a mass-spectrometry reference interval for adults in their reproductive years; the optimal band of 40 to 60 ng/dL is a functional target with no published threshold behind it, and no blood level defines low testosterone in a woman. Routine immunoassays are unreliable at female concentrations. Testosterone varies across the menstrual cycle, peaking around ovulation, declines with age and differs after menopause. In men, test in the morning and repeat a low result before acting on it.

Female context: These ranges are informative, not diagnostic, and reflect women in their reproductive years (pre-menopausal). Testosterone varies across the menstrual cycle, peaking around ovulation, so the ranges are intentionally wide. Levels also decline gradually with age and differ after menopause.

Sources

Last reviewed: November 9, 2026 · Total testosterone on its own page

Testosterone (Free)Functional / longevity targetSex-specificCycle-dependentAssay-dependentpg/mL · pmol/L · ng/dL · nmol/L

The free, active testosterone that is not bound to proteins.

UnitApplies toOptimalSufficientOut of range
pg/mLFemale1.5 – 40.5 – 4.5below 0.5 or above 4.5
pg/mLMale15 – 254.8 – 30below 4.8 or above 30
pmol/LFemale5.2 – 13.91.7 – 15.6below 1.7 or above 15.6
pmol/LMale52 – 8716.7 – 104below 16.7 or above 104
ng/dLFemale0.15 – 0.40.05 – 0.45below 0.05 or above 0.45
ng/dLMale1.5 – 2.50.48 – 3below 0.48 or above 3
nmol/LMale0.4 – 0.650.22 – 0.73below 0.22 or above 0.73
nmol/LFemale0.015 – 0.0360.008 – 0.047below 0.008 or above 0.047

Cycle: Female range spans the cycle, tracking total testosterone.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Free testosterone is reported on two scales that differ about tenfold, and the unit tells them apart. Results in pg/mL, pmol/L and ng/dL are read as a direct immunoassay; results in nmol/L are read as calculated free testosterone, worked out from total testosterone, SHBG and albumin. Equilibrium dialysis, which some laboratories report in ng/dL or pg/mL, runs several times higher than a direct assay and should be read against the report's own range. For men, the nmol/L lower edge of 0.22 is the European urology threshold for a low calculated free testosterone. The other edges, and all the optimal bands, are functional targets without a published source: Labcorp's direct-assay interval for men aged 20 to 29 is 9.3 to 26.5 pg/mL, narrower than the band here, and intervals fall with age. Direct assays are unreliable at female concentrations.

Female context: These ranges are informative, not diagnostic, and reflect women in their reproductive years (pre-menopausal). Free testosterone tracks total testosterone and varies across the menstrual cycle (peaking around ovulation), so the ranges are intentionally wide. It is also affected by SHBG and declines with age.

Sources

  • Testosterone, Total, Bioavailable, and Free, Serum (TTFB) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceFree testosterone by equilibrium dialysis: men 5.25 to 20.7 ng/dL at 20 to 25 years, falling to 3.67 to 13.9 at 60 to 65; women below 0.13 to 1.08 ng/dL at 20 to 25 years. Sera's male ng/dL band of 0.48 to 3 lies wholly below this interval.
  • Testosterone, Free, Direct (test 144980) — Labcorp, 2026 · Laboratory / reference-interval sourceDirect analog immunoassay: men 9.3 to 26.5 pg/mL at 20 to 29 years, falling to 6.6 to 18.1 over 59; women over 19, 0.0 to 4.2 pg/mL. This is the scale Sera's pg/mL rows are on, but no edge matches and women have no lower limit.
  • EAU Guidelines on Sexual and Reproductive Health: Male Hypogonadism — European Association of Urology, 2026 · Clinical guidelineA calculated free testosterone of 220 pmol/L (6.4 ng/dL) can be used as a threshold for hypogonadism where SHBG may be altered, on limited evidence. This equals Sera's male nmol/L lower edge of 0.22, and is about thirteen times Sera's pmol/L lower edge of 16.7.
  • Global Consensus Position Statement on the Use of Testosterone Therapy for Women — Davis SR, Baber R, Panay N, et al. — The Journal of Clinical Endocrinology & Metabolism, 2019 · Professional societyDirect assays for free testosterone are highly unreliable at female concentrations, so no female band can be defended for a direct-assay result.

Last reviewed: November 9, 2026 · Free testosterone on its own page

Free Testosterone %No universal rangeAuto-calculatedUnbanded% · unbanded

Free testosterone as a percentage of total testosterone.

Auto-calculated

Free testosterone ÷ total testosterone × 100

Calculated when Testosterone (Free) and Testosterone (Total) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

The only published interval is for free testosterone measured by equilibrium dialysis, which most laboratories do not use. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Calculated as free testosterone divided by total testosterone. Labcorp publishes 1.5 to 3.2 % for men and 0.8 to 1.4 % for women, but only for free testosterone measured by equilibrium dialysis. Most laboratories measure free testosterone by direct immunoassay, which reads lower, so Sera shows the percentage without a band. It mostly reflects SHBG: a high SHBG lowers it.

Sources

Last reviewed: November 9, 2026

Testosterone (Bioavailable)Published reference intervalSex-specificAssay-dependentng/dL · nmol/L

Free testosterone plus the testosterone loosely bound to albumin: the part not held by SHBG and available to tissues.

UnitApplies toOptimalSufficientOut of range
ng/dLMale40 – 250—below 40 or above 250
ng/dLFemale0 – 9.5—below 0 or above 9.5
nmol/LMale1.39 – 8.68—below 1.39 or above 8.68
nmol/LFemale0 – 0.33—below 0 or above 0.33

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The bands are Labcorp's interval for bioavailable testosterone measured by ammonium sulfate precipitation: 40 to 250 ng/dL for men and up to 9.5 ng/dL for women, with no low edge for women. Mayo's intervals fall with age in men, from 83 to 257 ng/dL in the twenties to 40 to 168 in the sixties, so a young man near the bottom of this band would be low at Mayo; Sera has no age-specific rows yet. The nmol/L rows are conversions; no UK or European interval was found. A bioavailable testosterone calculated from total testosterone, SHBG and albumin does not always agree with the measured one. No source supports a narrower optimal range.

Sources

  • Testosterone, Free and Weakly Bound (143255) — Labcorp, 2026 · Laboratory / reference-interval sourceBioavailable testosterone by ammonium sulfate precipitation: men 40 to 250 ng/dL, women 0 to 9.5 ng/dL. Sera's bands.
  • Testosterone, Free and Weakly Bound, With Total Testosterone, LC/MS-MS (FFTST; Labcorp 070282) — Labcorp (performing laboratory), Kootenai Health Laboratory catalog, 2026 · Laboratory / reference-interval sourceThe same Labcorp intervals, with total testosterone by LC-MS/MS: men 40 to 250 ng/dL, women 0 to 9.5 ng/dL.
  • Testosterone, Total and Bioavailable, Serum (TTBS) — Mayo Clinic Laboratories (performing laboratory), Torrance Memorial Laboratories catalog, 2026 · Laboratory / reference-interval sourceMen's intervals fall by decade, from 83 to 257 ng/dL at 20 to 29 down to 40 to 168 at 60 to 69; women 20 to 50 not on oral oestrogen 0.80 to 10 ng/dL. Context for the age effect Sera's single band does not capture.

Last reviewed: November 9, 2026 · Bioavailable testosterone on its own page

AMH (Anti-Müllerian Hormone)No universal rangeUnbandedAssay-dependentpmol/L · ng/mL · μg/L · unbanded

A hormone made by the small developing follicles in the ovaries, so it reflects how many eggs remain in the pool rather than how well any of them work.

No universal Sera range published.

Age-dependent and poorly standardised between platforms. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Sera does not score AMH. It falls steadily with age, so a normal result at 25 is a different number from a normal result at 40, and results differ between assay platforms. Guidelines ask laboratories to use cut-offs specific to their own assay and population. Use the age-banded range on the report. AMH reflects the number of remaining follicles and predicts the response to ovarian stimulation; in women not being treated for infertility, a low AMH has not been shown to predict the chance of conceiving. It is typically raised in PMOS (formerly polycystic ovary syndrome) and can be suppressed by hormonal contraception.

Sources

Last reviewed: November 9, 2026

ProlactinPublished reference intervalSex-specificng/mL · μg/L · mIU/L

A hormone best known for driving milk production.

UnitApplies toOptimalSufficientOut of range
ng/mLFemale5 – 204.8 – 23.3below 4.8 or above 23.3
ng/mLMale4 – 154 – 15.2below 4 or above 15.2
μg/LFemale5 – 204.8 – 23.3below 4.8 or above 23.3
μg/LMale4 – 154 – 15.2below 4 or above 15.2
mIU/LFemale106 – 424102 – 494below 102 or above 494
mIU/LMale85 – 31885 – 322below 85 or above 322

Interpretation: The bands are a laboratory reference interval for adults: 4.8 to 23.3 ng/mL in women and 4.0 to 15.2 in men (Mayo Clinic Laboratories). Other laboratories print higher upper limits, up to about 33 in women and 31 in young men, so a mildly raised result should be read against the report's own range. The narrower optimal bands are functional targets; no narrower target is published. Prolactin is only mildly cycle-dependent but rises with stress, sleep, exercise and nipple stimulation, with many medicines (antipsychotics, some antidepressants, metoclopramide, opiates, oestrogens), and is greatly elevated in pregnancy and breastfeeding. For a baseline, test in the morning, rested and not after exertion, and repeat a mildly raised result. These ranges are informative, not diagnostic.

Female context: This is an informative female reference range, not diagnostic. Prolactin is only mildly cycle-dependent but rises with stress, sleep, exercise, and nipple stimulation, and is greatly elevated during pregnancy and breastfeeding. For an accurate baseline, test in the morning, rested, and not after exertion.

Sources

  • Prolactin, Serum (PRL) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults aged 18 and over: men 4.0 to 15.2 ng/mL, women 4.8 to 23.3 ng/mL. Macroadenomas are typically associated with concentrations above 250 ng/mL.
  • Prolactin (test 004465) — Labcorp, 2026 · Laboratory / reference-interval sourceWomen 4.8 to 33.4 ng/mL from 13 to 50 years and 3.6 to 25.2 at 51 to 80; men 3.6 to 31.5 at 13 to 30 and 3.9 to 22.7 at 31 to 50. Shows that upper limits differ by laboratory and age: the female lower limit of 4.8 agrees with Mayo, the upper limits do not.

Last reviewed: November 9, 2026 · Prolactin on its own page

FSH (Follicle-Stimulating Hormone)Published reference intervalSex-specificCycle-dependentmIU/mL · IU/L

A pituitary hormone that helps control the reproductive system.

UnitApplies toOptimalSufficientOut of range
mIU/mLFemale3 – 101.7 – 21.5below 1.7 or above 21.5
mIU/mLMale2 – 81.5 – 12.4below 1.5 or above 12.4
IU/LFemale3 – 101.7 – 21.5below 1.7 or above 21.5
IU/LMale2 – 81.5 – 12.4below 1.5 or above 12.4

Cycle: Female range is a follicular-phase reference; FSH rises substantially after menopause.

Interpretation: The bands are laboratory reference intervals (Labcorp): 1.5 to 12.4 IU/L in men, and 1.7 to 21.5 in premenopausal women, which runs from the luteal lower limit to the mid-cycle upper limit. In the follicular phase alone the interval is narrower, about 3.5 to 12.5. For men, the optimal band ends at 8 IU/L, close to the 7.6 above which urology guidance suspects impaired sperm production in men being investigated for infertility. For women the optimal band of 3 to 10 IU/L is a functional target: a day-3 FSH above 10 is often quoted, but the reproductive-medicine society gives no cut-off and women above 10 conceived at similar rates in the cohort it cites. FSH varies across the cycle and rises substantially after menopause (generally above 25 to 40 IU/L), so interpret it with cycle day and menopausal status. These ranges are informative, not diagnostic.

Female context: These ranges are informative, not diagnostic, and reflect a follicular-phase reference for women in their reproductive years (pre-menopausal). FSH varies across the menstrual cycle and rises substantially after menopause, so interpret it alongside your cycle day and menopausal status.

Sources

  • Follicle-stimulating Hormone (FSH) (test 004309) — Labcorp, 2026 · Laboratory / reference-interval sourceAdult men 1.5 to 12.4 mIU/mL. Women: follicular 3.5 to 12.5, ovulatory 4.7 to 21.5, luteal 1.7 to 7.7, postmenopausal 25.8 to 134.8. Sera's male band of 1.5 to 12 matches; the female band of 1.5 to 20 is close to the luteal lower and ovulatory upper limits.
  • Follicle-Stimulating Hormone (FSH), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceMen over 18: 1.2 to 15.8 IU/L. Premenopausal women: follicular 2.9 to 14.6, midcycle 4.7 to 23.2, luteal 1.4 to 8.9; postmenopausal 16.0 to 157.0. Confirms the same pattern with slightly wider limits.
  • Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline — American Urological Association / American Society for Reproductive Medicine, 2020 · Clinical guidelineIn men with azoospermia, FSH above 7.6 IU/L suggests spermatogenic failure and FSH below it suggests obstruction. Supports an optimal upper edge of 7.6 in men, though the figure comes from infertile men only. Published 2020, amended 2024.
  • Testing and interpreting measures of ovarian reserve: a committee opinion — Practice Committee of the American Society for Reproductive Medicine — Fertility and Sterility, 2020 · Professional societyGives no diagnostic FSH cut-off. It cites a cohort in which women with FSH above 10 IU/L had similar cumulative pregnancy rates, so 10 is a study criterion, not a threshold for a worse outcome.

Last reviewed: November 9, 2026 · FSH on its own page

LH (Luteinizing Hormone)Published reference intervalSex-specificCycle-dependentmIU/mL · IU/L

A pituitary hormone that helps control reproduction.

UnitApplies toOptimalSufficientOut of range
mIU/mLFemale2 – 100.7 – 14.6below 0.7 or above 14.6
mIU/mLMale2 – 81.3 – 9.6below 1.3 or above 9.6
IU/LFemale2 – 100.7 – 14.6below 0.7 or above 14.6
IU/LMale2 – 81.3 – 9.6below 1.3 or above 9.6

Cycle: Female range is a follicular-phase reference; LH surges sharply at ovulation.

Interpretation: The bands are laboratory reference intervals (Mayo Clinic Laboratories): 1.3 to 9.6 IU/L in men, and 0.7 to 14.6 in premenopausal women outside the ovulatory surge. In pooled cohort data, men with LH above 10 IU/L had higher all-cause mortality, which fits the upper limit. No optimal band is published for either sex; the ones shown are functional targets. In women LH surges sharply at ovulation, to roughly 12 to 118 IU/L, so a mid-cycle result will score out of range without being abnormal; it is also markedly higher after menopause. Interpret a single value alongside cycle day, and alongside testosterone in men. These ranges are informative, not diagnostic.

Female context: These ranges are informative, not diagnostic, and reflect a follicular-phase reference for women in their reproductive years (pre-menopausal). LH surges sharply at ovulation and is markedly higher after menopause, so interpret a single value alongside your cycle day.

Sources

Last reviewed: November 9, 2026 · LH on its own page

Estradiol (E2)Published reference intervalSex-specificCycle-dependentAssay-dependentpg/mL · pmol/L · ng/L

The main form of estrogen.

UnitApplies toOptimalSufficientOut of range
pg/mLFemale50 – 20015 – 350below 15 or above 350
pg/mLMale20 – 4010 – 40below 10 or above 40
pmol/LFemale184 – 73455 – 1,287below 55 or above 1,287
pmol/LMale73 – 14737 – 147below 37 or above 147
ng/LFemale50 – 20015 – 350below 15 or above 350
ng/LMale20 – 4010 – 40below 10 or above 40

Cycle: Female range is a follicular-phase reference.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The bands are laboratory reference intervals (Mayo Clinic Laboratories, mass spectrometry): 10 to 40 pg/mL in men and 15 to 350 pg/mL in premenopausal women across the whole cycle. No optimal band is published for either sex; the ones shown are functional targets. In women estradiol swings widely: low early in the follicular phase (roughly 12 to 166 pg/mL), peaking just before ovulation (up to about 500), with a second mid-luteal rise, so a single value only means something alongside cycle day. Levels fall sharply after menopause, typically below 10 pg/mL. These ranges are informative, not diagnostic.

Female context: These ranges are informative, not diagnostic, and reflect a follicular-phase reference for women in their reproductive years (pre-menopausal). Estradiol swings dramatically across the menstrual cycle — low early in the follicular phase, peaking just before ovulation, with a second mid-luteal rise — so a single value is only meaningful alongside your cycle day. Levels fall sharply after menopause.

Sources

  • Estradiol, Serum (EEST) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults by mass spectrometry: men 10 to 40 pg/mL, premenopausal women 15 to 350 pg/mL (varies widely through the cycle), postmenopausal women below 10. Conversion: pg/mL x 3.676 = pmol/L.
  • Estradiol (test 004515) — Labcorp, 2026 · Laboratory / reference-interval sourceAdult men 7.6 to 42.6 pg/mL. Women: follicular 12.5 to 166.0, ovulation 85.8 to 498.0, luteal 43.8 to 211.0, postmenopausal below 6.0 to 54.7. Roche immunoassay. Confirms a male upper limit near 40 and shows how wide the female range is by phase.

Last reviewed: November 9, 2026 · Estradiol on its own page

SHBG (Sex Hormone-Binding Globulin)Published reference intervalSex-specificnmol/L

A protein that binds to sex hormones and carries them in the blood.

UnitApplies toOptimalSufficientOut of range
nmol/LFemale40 – 10018.2 – 135.5below 18.2 or above 135.5
nmol/LMale20 – 5513.3 – 89.5below 13.3 or above 89.5

Interpretation: The bands are a laboratory reference interval (Mayo Clinic Laboratories): 13.3 to 89.5 nmol/L in men and 18.2 to 135.5 in women of reproductive age. Other laboratories print narrower, age-banded limits. No optimal band is published, and the ones shown are functional targets; in cohort data, men with lower SHBG did not fare worse. SHBG is relatively stable across the menstrual cycle but is strongly influenced by thyroid status, insulin and insulin resistance, oestrogen (including oral contraceptives and HRT), body weight and liver function: it is typically low in insulin resistance and PMOS (formerly polycystic ovary syndrome) and high in hyperthyroidism, with oral oestrogen and in anorexia. Interpret it alongside the sex hormones rather than in isolation. These ranges are informative, not diagnostic.

Female context: This is an informative female reference range, not diagnostic. SHBG is relatively stable across the menstrual cycle but is strongly influenced by thyroid status, insulin and insulin resistance, estrogen (including oral contraceptives and HRT), and liver function. Interpret it alongside your sex hormones rather than in isolation.

Sources

Last reviewed: November 9, 2026 · SHBG on its own page

FAI (Free Androgen Index)Published reference intervalAuto-calculatedSex-specific

An estimate of how much active testosterone is available to the body, worked out from total testosterone and SHBG. Because most testosterone is bound to SHBG and inactive, FAI gives a clearer picture of usable androgen than total testosterone on its own. The name stands for Free Androgen Index.

Auto-calculated

(Total Testosterone / SHBG) × 100 (both in nmol/L)

Calculated when Testosterone (Total) and SHBG (Sex Hormone-Binding Globulin) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitApplies toOptimalSufficientOut of range
ratioFemale1 – 40.3 – 5.6below 0.3 or above 5.6

Interpretation: The free androgen index is total testosterone divided by SHBG, times 100, and is used in women as a rough estimate of free testosterone when looking for androgen excess, as in PMOS (formerly polycystic ovary syndrome). The women's acceptable band of 0.3 to 5.6 is one NHS laboratory's reference interval for ages 20 to 49; other laboratories print upper limits of 7 to 11, because the result depends on the testosterone and SHBG assays used, and guidelines give no single cut-off. The narrower optimal band of 1 to 4 is a functional target with no published threshold behind it. Sera does not score the index in men, where laboratories do not report it: use total testosterone, with calculated free testosterone where SHBG is abnormal.

Sources

  • Free Androgen Index — York and Scarborough Teaching Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceWomen aged 20 to 49: 0.3 to 5.6%; over 50: 0.2 to 3.6%. The index is reported for women only. Matches Sera's female sufficient band exactly. Page undated; current test directory.
  • Free Androgen Index (FAI) — Gloucestershire Hospitals NHS Foundation Trust, 2025 · Laboratory / reference-interval sourceWomen aged 20 to 50: 0.18 to 7.07%; over 50: 0.10 to 4.95%. Valid only for the local Roche assays and a normal albumin. No male range. Shows the upper limit is assay-specific.
  • Free androgen index — North Bristol NHS Trust (Severn Pathology), 2026 · Laboratory / reference-interval sourceWomen aged 18 to 46: 0.7 to 10.9%; 47 and over: 0.2 to 6.8%. Calculated for women only. A third laboratory with a different upper limit. Page undated; current test directory.
  • Recommendations From the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome — Teede HJ, Tay CT, Laven JJE, et al. — The Journal of Clinical Endocrinology & Metabolism, 2023 · Clinical guidelineThe index may be used to estimate free testosterone when assessing biochemical hyperandrogenism in women. No numeric cut-off is given, and reference ranges are said to vary widely between methods and laboratories.

Last reviewed: November 9, 2026 · Free androgen index on its own page

ProgesteronePublished reference intervalSex-specificCycle-dependentAssay-dependentng/mL · nmol/L

A hormone needed for the menstrual cycle and for pregnancy.

UnitApplies toOptimalSufficientOut of range
ng/mLFemale10 – 255 – 25below 5 or above 25
ng/mLMale0.2 – 0.90.1 – 1.4below 0.1 or above 1.4
nmol/LFemale32 – 7916 – 79below 16 or above 79
nmol/LMale0.6 – 2.90.3 – 4.5below 0.3 or above 4.5

Cycle: Female range is a luteal-phase reference, ideally drawn about 7 days after ovulation.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: For women the bands are read against the luteal phase: Mayo Clinic Laboratories states that a result above 10 ng/mL on days 21 to 23 indicates normal ovulation, which is the optimal lower edge, and MedlinePlus gives 5 to 20 mid-cycle, which is the acceptable lower edge. The upper edge of 25 has no exact source; Mayo's luteal interval ends at 24. A follicular-phase or postmenopausal result will read low without being abnormal. For men, laboratories give an upper limit only, so the male lower edges have no source.

Female context: These ranges are informative, not diagnostic, and reflect a luteal-phase reference for women in their reproductive years (pre-menopausal). Progesterone is very low in the follicular phase and rises sharply only after ovulation, so the ranges are wide and must be read against your cycle day (ideally tested ~7 days after ovulation).

Sources

  • PGSN - Overview: Progesterone, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult women, luteal phase: 1.8 to 24 ng/mL; follicular 0.89 or less; post-menopausal 0.20 or less. Day 21 to 23 progesterone above 10 ng/mL indicates normal ovulation. Adult men: below 0.20 ng/mL. Matches Sera's female optimal lower edge of 10 and supports an upper edge of 24.
  • Serum progesterone — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceMid-cycle women: 5 to 20 ng/mL (15.9 to 63.6 nmol/L). Pre-ovulation women, men and postmenopausal women: less than 1 ng/mL (3.18 nmol/L). Matches Sera's female sufficient lower edge of 5 and gives a male upper limit of 1.

Last reviewed: November 9, 2026 · Progesterone on its own page

Cortisol (Morning)Published reference intervalμg/dL · nmol/L · ng/mL

Your cortisol level in the morning, which reflects how the adrenal glands are working.

UnitOptimalSufficientOut of range
μg/dL10 – 185 – 25below 5 or above 25
nmol/L276 – 497138 – 690below 138 or above 690
ng/mL100 – 18050 – 250below 50 or above 250

Interpretation: For a sample drawn at about 8 am. The acceptable band is the 5 to 25 μg/dL (138 to 690 nmol/L) morning interval published by MedlinePlus; laboratory intervals vary with the assay (Mayo 7 to 25, Labcorp 6.2 to 19.4). The optimal band starts at 10 μg/dL (300 nmol/L), which the 2024 European and US endocrine society guideline treats as a reasonable sign of normal adrenal function; a morning result below 5 μg/dL makes adrenal insufficiency very likely and needs medical follow-up. The optimal ceiling of 18 μg/dL is a functional target with no published threshold behind it. Oral oestrogen raises total cortisol, and a single sample cannot diagnose Cushing syndrome or adrenal insufficiency.

Sources

  • Cortisol blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal values for a sample taken at 8 in the morning are 5 to 25 mcg/dL (138 to 690 nmol/L). Supports a sufficient band of 5 to 25 μg/dL.
  • CORT - Overview: Cortisol, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults: a.m. 7 to 25 mcg/dL, p.m. 2 to 14 mcg/dL. With symptoms of glucocorticoid deficiency, an 8 a.m. cortisol below 10 mcg/dL calls for further studies. Supports the morning upper edge of 25 and the afternoon band of 2 to 14.
  • Cortisol — Labcorp, 2026 · Laboratory / reference-interval sourceReference interval: AM 6.2 to 19.4 μg/dL, PM 2.3 to 11.9 μg/dL. A narrower interval than Mayo's on a different assay; shows how far the upper limit moves between laboratories.
  • European Society of Endocrinology and Endocrine Society Joint Clinical Guideline: Diagnosis and Therapy of Glucocorticoid-induced Adrenal Insufficiency — European Society of Endocrinology and Endocrine Society (Beuschlein F, Else T, Bancos I, et al. — The Journal of Clinical Endocrinology and Metabolism), 2024 · Clinical guidelineA morning cortisol above 300 nmol/L (10 μg/dL) is taken as a reasonable threshold for recovery of adrenal function; below 150 nmol/L (5 μg/dL) adrenal insufficiency is very likely. The guideline is about people coming off glucocorticoids, and it says cortisol should be read as a continuum. Supports an optimal lower edge of 10 μg/dL and a sufficient lower edge of 5.

Last reviewed: November 9, 2026 · Morning cortisol on its own page

Cortisol (Afternoon/Evening)Published reference intervalμg/dL · nmol/L · ng/mL

Your cortisol level in the afternoon or evening, which shows your daily cortisol rhythm.

UnitOptimalSufficientOut of range
μg/dL2 – 82 – 11below 2 or above 11
nmol/L55 – 22155 – 303below 55 or above 303
ng/mL20 – 8020 – 110below 20 or above 110

Interpretation: For an afternoon or evening sample. The lower edge of 2 μg/dL matches Mayo Clinic Laboratories' p.m. interval of 2 to 14; the acceptable upper edge of 11 is close to Labcorp's 11.9 and matches neither exactly. No guideline sets a threshold for an afternoon serum cortisol, and the optimal ceiling of 8 is a functional target with no published source.

Sources

  • CORT - Overview: Cortisol, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults, p.m. sample: 2 to 14 mcg/dL. Matches Sera's lower edge of 2 and supports a sufficient upper edge of 14.
  • Cortisol — Labcorp, 2026 · Laboratory / reference-interval sourcePM reference interval 2.3 to 11.9 μg/dL, a lower ceiling than Mayo's on a different assay.

Last reviewed: November 9, 2026 · Afternoon or evening cortisol on its own page

DHEA-S (Dehydroepiandrosterone Sulfate)Published reference intervalSex-specificμg/dL · μmol/L · ng/mL

An adrenal hormone that the body uses as a building block for sex hormones.

UnitApplies toOptimalSufficientOut of range
μg/dLFemale, 18 to 20—74 – 403below 74 or above 403
μg/dLFemale, 21 to 30—67 – 373below 67 or above 373
μg/dLFemale, 31 to 40—46 – 294below 46 or above 294
μg/dLFemale, 41 to 50—32 – 236below 32 or above 236
μg/dLFemale, 51 to 60—24 – 210below 24 or above 210
μg/dLFemale, 61 to 70—18 – 195below 18 or above 195
μg/dLFemale, 71 to 80—14 – 167below 14 or above 167
μg/dLFemale, 81 and over—12 – 122below 12 or above 122
μg/dLMale, 18 to 20—84 – 451below 84 or above 451
μg/dLMale, 21 to 30—96 – 475below 96 or above 475
μg/dLMale, 31 to 40—71 – 384below 71 or above 384
μg/dLMale, 41 to 50—48 – 333below 48 or above 333
μg/dLMale, 51 to 60—29 – 285below 29 or above 285
μg/dLMale, 61 to 70—20 – 281below 20 or above 281
μg/dLMale, 71 to 80—15 – 249below 15 or above 249
μg/dLMale, 81 and over—12 – 137below 12 or above 137
μmol/LFemale, 18 to 20—2.01 – 10.94below 2.01 or above 10.94
μmol/LFemale, 21 to 30—1.82 – 10.12below 1.82 or above 10.12
μmol/LFemale, 31 to 40—1.25 – 7.98below 1.25 or above 7.98
μmol/LFemale, 41 to 50—0.87 – 6.41below 0.87 or above 6.41
μmol/LFemale, 51 to 60—0.65 – 5.7below 0.65 or above 5.7
μmol/LFemale, 61 to 70—0.49 – 5.29below 0.49 or above 5.29
μmol/LFemale, 71 to 80—0.38 – 4.53below 0.38 or above 4.53
μmol/LFemale, 81 and over—0.33 – 3.31below 0.33 or above 3.31
μmol/LMale, 18 to 20—2.28 – 12.24below 2.28 or above 12.24
μmol/LMale, 21 to 30—2.61 – 12.89below 2.61 or above 12.89
μmol/LMale, 31 to 40—1.93 – 10.42below 1.93 or above 10.42
μmol/LMale, 41 to 50—1.3 – 9.04below 1.3 or above 9.04
μmol/LMale, 51 to 60—0.79 – 7.73below 0.79 or above 7.73
μmol/LMale, 61 to 70—0.54 – 7.63below 0.54 or above 7.63
μmol/LMale, 71 to 80—0.41 – 6.76below 0.41 or above 6.76
μmol/LMale, 81 and over—0.33 – 3.72below 0.33 or above 3.72
ng/mLFemale, 18 to 20—740 – 4,030below 740 or above 4,030
ng/mLFemale, 21 to 30—670 – 3,730below 670 or above 3,730
ng/mLFemale, 31 to 40—460 – 2,940below 460 or above 2,940
ng/mLFemale, 41 to 50—320 – 2,360below 320 or above 2,360
ng/mLFemale, 51 to 60—240 – 2,100below 240 or above 2,100
ng/mLFemale, 61 to 70—180 – 1,950below 180 or above 1,950
ng/mLFemale, 71 to 80—140 – 1,670below 140 or above 1,670
ng/mLFemale, 81 and over—120 – 1,220below 120 or above 1,220
ng/mLMale, 18 to 20—840 – 4,510below 840 or above 4,510
ng/mLMale, 21 to 30—960 – 4,750below 960 or above 4,750
ng/mLMale, 31 to 40—710 – 3,840below 710 or above 3,840
ng/mLMale, 41 to 50—480 – 3,330below 480 or above 3,330
ng/mLMale, 51 to 60—290 – 2,850below 290 or above 2,850
ng/mLMale, 61 to 70—200 – 2,810below 200 or above 2,810
ng/mLMale, 71 to 80—150 – 2,490below 150 or above 2,490
ng/mLMale, 81 and over—120 – 1,370below 120 or above 1,370

Interpretation: DHEA-S falls steeply with age, so Sera reads it against the band for the client's age and sex on the day of the draw: eight age groups from 18 to 20 up to 81 and over, taken from Labcorp's mass-spectrometry interval. For women the band runs 67 to 373 μg/dL at 21 to 30 and 24 to 210 at 51 to 60; for men, 96 to 475 and 29 to 285. With no date of birth there is no band, and no status. There is no optimal band: no published source gives one for any age. Cohort studies link a result in the lowest fifth for age and sex to higher mortality, but they give no target number. Laboratories disagree most for adults under 35, where immunoassays read higher than mass spectrometry, so a young client's own laboratory may print a higher lower limit than Sera's; read a borderline result against the report's range. Time of day makes little difference. DHEA supplements raise it and glucocorticoid tablets lower it.

Female context: This is an informative female reference range, not diagnostic. Unlike the reproductive hormones, DHEA-S does not vary meaningfully across the menstrual cycle. It declines steadily with age, so the range shown is the one for your age at the latest result.

Sources

  • DHEA sulfate (LC-MS/MS), test 005165 — Labcorp, 2026 · Laboratory / reference-interval sourceEvery edge of Sera's age bands. Mass-spectrometry intervals by sex and age from 17 to over 80, in μg/dL, from Labcorp in-house data: women 21 to 30, 67 to 373; 51 to 60, 24 to 210; 71 to 80, 14 to 167; men 21 to 30, 96 to 475; 51 to 60, 29 to 285; 71 to 80, 15 to 249. Sera's 18 to 20 row uses Labcorp's 19 to 20 interval.
  • DHEA-sulfate test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2026 · Government / public-health guidanceTypical ranges by age. Women: 18 to 29, 45 to 320 μg/dL; 30 to 39, 40 to 325; 40 to 49, 25 to 220; 50 to 59, 15 to 170; above 59, less than 145. Men: 18 to 29, 110 to 510; 30 to 39, 110 to 370; 40 to 49, 45 to 345; 50 to 59, 25 to 240; above 59, less than 204. The numbers are in two tables on the page, which were read; the quote is the sentence introducing them.
  • Dehydroepiandrosterone sulphate, serum — Newcastle upon Tyne Hospitals NHS Foundation Trust Laboratories, 2024 · Laboratory / reference-interval sourceA UK mass-spectrometry interval by age that falls with age in the same way (women 20 to 39, 1.2 to 8.0 μmol/L; 60 and over, 0.1 to 4.8), and the statement that DHEA-S shows no significant diurnal variation, so the time of the draw does not matter.

Last reviewed: November 9, 2026 · DHEA-S on its own page

DHEA (Dehydroepiandrosterone)Functional / longevity targetAssay-dependentng/mL · nmol/L

The unsulfated adrenal androgen precursor, distinct from the far more abundant DHEA-S.

UnitOptimalSufficientOut of range
ng/mL2 – 101 – 14below 1 or above 14
nmol/L6.9 – 34.73.5 – 48.5below 3.5 or above 48.5

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: A different test from DHEA-S and not comparable with it. DHEA has a diurnal rhythm and swings hour to hour, which is why DHEA-S — stable, long half-life — is the usual measure of adrenal output. Both fall steadily from the third decade, so an age-matched reading matters more than the population interval. Published intervals are age-specific and differ between laboratories: Mayo gives upper limits only, from 13 ng/mL at 19 to 30 down to 5 from 61, and Labcorp gives 0.84 to 4.92 for men and 0.90 to 5.30 for women at 31 to 40. Sera's bands match neither, and the lower edge of 1 ng/mL flags results those laboratories call normal. The optimal band of 2 to 10 is a functional target with no published source.

Sources

  • DHEA_ - Overview: Dehydroepiandrosterone (DHEA), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult upper limits by age, no lower limit: 19 to 30 years below 13 ng/mL; 31 to 40 below 10; 41 to 50 below 8.0; 51 to 60 below 6.0; 61 and over below 5.0. Supports a sufficient upper edge of 13 ng/mL.
  • DHEA by Ionify LC-MS/MS (test 004389) — Labcorp, 2026 · Laboratory / reference-interval sourceAge- and sex-specific LC-MS/MS intervals that fall with age: 21 to 30 years, men 1.23 to 6.22 ng/mL and women 1.32 to 7.18; 41 to 50, men 0.56 to 3.93 and women 0.61 to 4.33; 61 to 70, men 0.23 to 2.61 and women 0.34 to 3.53. From 31 years the lower limits fall below Sera's 1 ng/mL.

Last reviewed: November 9, 2026

AndrostenedionePublished reference intervalSex-specificAssay-dependentng/mL · nmol/L

An androgen precursor made by both the adrenal glands and the gonads, sitting one step before testosterone.

UnitApplies toOptimalSufficientOut of range
ng/mLMale0.5 – 1.50.4 – 1.5below 0.4 or above 1.5
ng/mLFemale0.5 – 20.3 – 2below 0.3 or above 2
nmol/LMale1.75 – 5.21.4 – 5.2below 1.4 or above 5.2
nmol/LFemale1.75 – 71.05 – 7below 1.05 or above 7

Cycle: Varies across the menstrual cycle, peaking around ovulation.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Useful when testosterone is equivocal but the picture suggests androgen excess. Raised in PMOS (formerly polycystic ovary syndrome) and congenital adrenal hyperplasia. Varies across the menstrual cycle and declines with age. The bands are Mayo Clinic Laboratories' adult intervals: 0.4 to 1.5 ng/mL (40 to 150 ng/dL) for men and 0.3 to 2.0 ng/mL (30 to 200 ng/dL) for women. Labcorp's interval for women aged 15 to 60 runs higher, to 2.55 ng/mL, and both sexes run lower after 60, so check the laboratory's own interval. Mayo notes that 5 ng/mL (500 ng/dL) or more can point to an androgen-secreting tumour. No published evidence defines an optimal level, so the optimal band shown is a functional target.

Sources

  • ANST - Overview: Androstenedione, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults by LC-MS/MS: men 40 to 150 ng/dL, women 30 to 200 ng/dL. Levels of 500 ng/dL or more can suggest an androgen-secreting tumour. Supports sex-specific bands of 0.4 to 1.5 ng/mL for men and 0.3 to 2.0 for women.
  • Androstenedione by Ionify LC-MS/MS (test 004774) — Labcorp, 2026 · Laboratory / reference-interval sourceAges 15 to 60: men 28 to 167 ng/dL, women 39 to 255 ng/dL. Ages 61 to 80: men 20 to 115, women 16 to 105. Puts the male upper limit at 167 ng/dL, above Mayo's 150, and shows the female limit varies by assay and age.

Last reviewed: November 9, 2026 · Androstenedione on its own page

17-Hydroxyprogesterone (17-OHP)Established clinical thresholdAssay-dependentng/mL · nmol/L

The steroid immediately upstream of the 21-hydroxylase step, which accumulates when that enzyme is deficient.

UnitOptimalSufficientOut of range
ng/mL0 – 11 – 2below 0 or above 2
nmol/L0 – 33 – 6.1below 0 or above 6.1

Cycle: Range is a follicular-phase reference. The luteal phase runs several-fold higher, which is normal rather than a finding.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The screening test for congenital adrenal hyperplasia, including the non-classical adult form that mimics PMOS (formerly polycystic ovary syndrome). Draw it in the morning, and in a menstruating woman in the follicular phase — a luteal sample reads several-fold higher for entirely normal reasons. A clearly raised morning follicular value warrants a stimulation test rather than a diagnosis. The upper edge of 2 ng/mL (200 ng/dL, 6 nmol/L) is the recognised screening threshold: MedlinePlus states that an adult level above it may be due to non-classical adrenal hyperplasia. Draw it early in the morning in the follicular phase; luteal-phase results run higher. The narrower optimal edge is a functional target. The upper edge of 2 ng/mL (200 ng/dL, 6 nmol/L) is the recognised screening threshold: MedlinePlus states that an adult level above it may be due to non-classical adrenal hyperplasia, and Mayo Clinic Laboratories gives a follicular-phase limit of 0.8 against 2.85 luteal. The narrower optimal edge is a functional target.

Sources

  • 17-OH progesterone — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceIn adults a level above 200 ng/dL (6.06 nmol/L) may be due to non-classical adrenal hyperplasia. Normal adult women 0 to 290 ng/dL depending on cycle phase, men 0 to 139. Matches Sera's upper edge of 2 ng/mL.
  • OHPG - Overview: 17-Hydroxyprogesterone, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults by LC-MS/MS: men below 220 ng/dL; women follicular below 80 ng/dL, luteal below 285, postmenopausal below 51. Supports a female follicular optimal ceiling of 0.8 ng/mL and shows why a luteal sample reads higher.

Last reviewed: November 9, 2026 · 17-OHP on its own page

IGF-1 (Insulin-like Growth Factor-1)Functional / longevity targetng/mL · nmol/L

A marker that reflects how much growth hormone your body is making and affects metabolism.

UnitOptimalSufficientOut of range
ng/mL150 – 250100 – 350below 100 or above 350
nmol/L19.6 – 32.713.1 – 45.8below 13.1 or above 45.8

Interpretation: IGF-1 has no single adult range: laboratories report it by age, and it falls steadily through adult life. Sera uses one band for all adults, so its lower edge of 100 ng/mL flags results that are normal for an older adult. The optimal band of 150 to 250 is a functional target; a 2022 meta-analysis of cohort studies found the lowest mortality at 120 to 160. Read the result against the age-specific range on the report.

Sources

  • IGF-1, LC/MS (Test Code GF1M) — Quest Diagnostics Nichols Institute, as listed in the UnityPoint Health Waterloo test catalog, 2026 · Laboratory / reference-interval sourceAdult intervals in ng/mL: 20 to 24.9 years 83 to 456; 25 to 29.9, 63 to 373; 30 to 39.9, 53 to 331; 40 to 49.9, 52 to 328; 50 to 59.9, 50 to 317; 60 to 69.9, 41 to 279; 70 to 79.9, 34 to 245. Supports a band spanning 34 to 456 for adults of 20 and over.
  • Association between IGF-1 levels ranges and all-cause mortality: A meta-analysis — Rahmani J, Montesanto A, Giovannucci E, et al. — Aging Cell, 2022 · Peer-reviewed publicationMeta-analysis of cohort studies: both low and high IGF-1 raise all-cause mortality, with the lowest mortality at 120 to 160 ng/mL. Supports an optimal band of 120 to 160; it does not support Sera's 150 to 250.

Last reviewed: November 9, 2026

LeptinNo universal rangeUnbandedng/mL · μg/L · unbanded

A hormone released by adipose tissue that signals energy sufficiency to the hypothalamus.

No universal Sera range published.

Tracks fat mass and differs substantially by sex, so a universal band would misread most results. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Leptin is made by fat tissue, so the level tracks fat mass and runs several times higher in women than in men. Laboratories publish intervals only for a stated body mass index: Mayo Clinic Laboratories gives 0.7 to 5.3 ng/mL for men and 3.3 to 18.3 ng/mL for women at a BMI of 22, and other ranges on request. No guideline sets a threshold, so Sera shows the result without a band. Read it against the laboratory's own interval and the client's body composition.

Sources

  • FLEP - Overview: Leptin — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults at a BMI of 22: men 0.7 to 5.3 ng/mL, women 3.3 to 18.3 ng/mL; the laboratory must be contacted for ranges at other BMIs. Confirms there is no universal band.

Last reviewed: November 9, 2026

Prostate Health · 2 markers

Prostate-specific antigen, total and free — shown only on male clients

PSA (Total)Established clinical thresholdng/mL · μg/L

Prostate-specific antigen, a protein made by the prostate and measurable in the blood of anyone who has one.

UnitOptimalSufficientOut of range
ng/mL0 – 2.52.5 – 4below 0 or above 4
μg/L0 – 2.52.5 – 4below 0 or above 4

Interpretation: The acceptable band ends at 4.0 ng/mL, the cutoff the US National Cancer Institute describes as generally abnormal and the upper limit of common laboratory reference intervals. It is a long-standing convention rather than a boundary between health and disease: cancer occurs below it and most men above it do not have it. The optimal band ending at 2.5 ng/mL is not an outcome-based target; 2.5 is the lower cutoff some doctors use for younger men and the NICE referral threshold for men aged 40 to 49. UK practice is age-specific (above 3.5 at 50 to 59, 4.5 at 60 to 69, 6.5 at 70 to 79) or 3 ng/mL at any age in the screening-programme guidance, so a man in his 60s or 70s can be above 4.0 and still under his age threshold. Benign enlargement, prostatitis or a urine infection, recent ejaculation, vigorous exercise such as cycling and a digital examination can raise it; finasteride and dutasteride lower it, conventionally by about half, so double the result on either. A trend across draws beats any single value.

Sources

  • Prostate-Specific Antigen (PSA) Test — National Cancer Institute (NIH), 2025 · Government / public-health guidanceA PSA above 4.0 ng/mL is generally considered abnormal and may lead to a biopsy recommendation; some doctors use a lower cutoff such as 2.5 ng/mL for younger men and a higher one such as 5 for older men. There is no single threshold separating normal from abnormal. Matches Sera's sufficient upper 4.0 and names the 2.5 figure used as the optimal upper.
  • Screening Tests for Prostate Cancer — American Cancer Society, 2023 · Professional societyMany doctors use 4 ng/mL as the cutoff for further testing, others start at 2.5 or 3. Most men without prostate cancer are under 4; between 4 and 10 the chance of cancer is about 1 in 4, above 10 it is over 50%. A level below 4 does not rule cancer out.
  • Prostate Specific Antigen, Total with Reflex to Free PSA (Includes Free Percentage) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP's laboratory reference interval for total PSA is 0.0 to 4.0 ng/mL; free PSA is added when the total is 3.0 to 10.0 ng/mL. Matches Sera's sufficient band of 0 to 4. Test directory page as opened in October 2026; the page carries no publication date.
  • Diagnosis of prostate cancer in primary care: navigating updated clinical guidance — Merriel SWD, Seggie A, Ahmed H — The British Journal of General Practice, 2023 · Peer-reviewed publicationReproduces the NICE NG12 (2021 update) referral thresholds for men with possible symptoms: above 2.5 micrograms/L at 40 to 49, 3.5 at 50 to 59, 4.5 at 60 to 69, 6.5 at 70 to 79, clinical judgement outside those ages. Also states the UK Prostate Cancer Risk Management Programme uses 3 ng/mL regardless of age. Shows 2.5 is the UK threshold for men in their 40s, and that UK practice does not use a flat 4.0. Full text read through the Europe PMC full-text service for PMC9888566.
  • Prostate-Specific Antigen (PSA) Test: MedlinePlus Medical Test — MedlinePlus, US National Library of Medicine, 2025 · Government / public-health guidanceStates that no specific PSA level is normal or abnormal and gives no numeric cutoff. Supports the note's statement that 4.0 is a convention, not a boundary between health and disease; it does not support any band edge.

Last reviewed: November 9, 2026 · Total PSA on its own page

Free PSANo universal rangeUnbandedng/mL · μg/L · unbanded

The fraction of PSA circulating unbound to protein, reported alongside the total.

No universal Sera range published.

The absolute value has no threshold of its own; the recognised cut-offs apply to percent free PSA. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Sera publishes no band for absolute free PSA. Laboratories report it so that percent free PSA can be calculated, and no accepted adult range exists for the ng/mL value on its own: ARUP and Labcorp publish no interval, and where a laboratory does give one it is specific to its assay. Free PSA is only meaningful as a percentage of the total, and only when the total sits in the 4 to 10 ng/mL grey zone. Above roughly 25% free favours benign enlargement; 10% or less concentrates risk, with laboratory tables putting the chance of cancer on biopsy at about 50 to 65% at 10% or less and about 5 to 16% above 25%, rising with age. Calculate the percentage against the total on the same panel and the same assay.

Sources

  • Screening Tests for Prostate Cancer — American Cancer Society, 2023 · Professional societyPercent-free PSA is used when total PSA is in the borderline range of 4 to 10 ng/mL: many doctors recommend biopsy at 10% or less and advise considering one between 10% and 25%. Not all doctors agree that 25% is the best cutoff. Supports the note's 10% and 25% figures; gives no absolute free PSA range.
  • Prostate Specific Antigen, Free Percentage (Includes Free PSA and Total PSA) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP gives no fixed reference interval for free PSA ('By report'). With total PSA 4 to 10 ng/mL, the probability of cancer on biopsy at ages 50 to 59, 60 to 69 and 70 or over is 49%, 58% and 65% at 0 to 10% free, and 9%, 12% and 16% above 25% free. Test directory page as opened in October 2026; no publication date on the page.
  • Prostate-specific Antigen (PSA), Free:Total Ratio Reflex — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp lists no reference interval for absolute free PSA. For men with a nonsuspicious examination and total PSA 4.0 to 10.0 ng/mL, cancer probability is 56% (ages 50 to 64) and 55% (65 to 75) at 0 to 10% free, falling to 5% and 9% above 25% free. Test directory page as opened in October 2026.
  • Prostate-Specific Antigen (PSA), Free — University of Florida Health Pathology Laboratories, 2026 · Laboratory / reference-interval sourceThis laboratory's reference range for free PSA by chemiluminescence is 0.70 ng/mL or less, with no lower limit. It does not match Sera's upper edges of 4 or 6 ng/mL or the lower edges of 0.25 and 0.15, and shows that any absolute range is laboratory-specific. Page carries only a 2026 copyright date.

Last reviewed: November 9, 2026

Blood Cell Health · 35 markers

Red cells, white cells, platelets, and iron-status markers

RBC # (Red Blood Cell Count)Published reference intervalSex-specific×10⁶/μL · ×10¹²/L · millions/μL · M/μL · x E12/L · /mm³

The total number of red blood cells in your blood.

UnitApplies toOptimalSufficientOut of range
×10⁶/μLMale4.8 – 5.54.3 – 5.9below 4.3 or above 5.9
×10⁶/μLFemale4.2 – 4.83.9 – 5.4below 3.9 or above 5.4
×10¹²/LMale4.8 – 5.54.3 – 5.9below 4.3 or above 5.9
×10¹²/LFemale4.2 – 4.83.9 – 5.4below 3.9 or above 5.4
millions/μLMale4.8 – 5.54.3 – 5.9below 4.3 or above 5.9
millions/μLFemale4.2 – 4.83.9 – 5.4below 3.9 or above 5.4
M/μLMale4.8 – 5.54.3 – 5.9below 4.3 or above 5.9
M/μLFemale4.2 – 4.83.9 – 5.4below 3.9 or above 5.4
x E12/LMale4.8 – 5.54.3 – 5.9below 4.3 or above 5.9
x E12/LFemale4.2 – 4.83.9 – 5.4below 3.9 or above 5.4
/mm³Male4,800,000 – 5,500,0004,300,000 – 5,900,000below 4,300,000 or above 5,900,000
/mm³Female4,200,000 – 4,800,0003,900,000 – 5,400,000below 3,900,000 or above 5,400,000

Interpretation: The acceptable bands sit within 0.1 of published adult intervals, which differ a little between laboratories: MedlinePlus gives 4.2 to 5.7 for men and 3.8 to 5.1 for women on one page and 4.6 to 6.2 and 4.2 to 5.4 on another. Only the women's upper edge of 5.4 matches a source exactly. The optimal bands are functional targets with no published source.

Sources

  • RBC count — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2026 · Government / public-health guidanceNormal red cell count is 4.2 to 5.7 million cells per microlitre in men and 3.8 to 5.1 in women (reviewed February 2026). Sera's lower edges of 4.3 and 3.9 are each 0.1 above these.
  • CBC blood test — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2024 · Government / public-health guidanceA second MedlinePlus page gives 4.6 to 6.2 million cells per microlitre for men and 4.2 to 5.4 for women. The women's upper limit of 5.4 is Sera's number.
  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult red cell count 4.50 to 6.50 ×10¹²/L in men and 3.80 to 5.80 in women. Supports 3.8 as the women's lower limit.
  • Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceRed cell count 4.4 to 6.0 ×10¹²/L in men and 4.2 to 5.4 in women. Supports 6.0 as a men's upper limit and 5.4 as the women's. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.

Last reviewed: November 9, 2026 · Red blood cell count on its own page

Hemoglobin (HGB)Established clinical thresholdSex-specificg/dL · g/L · mmol/L

The protein in red blood cells that carries oxygen.

UnitApplies toOptimalSufficientOut of range
g/dLFemale13.5 – 14.512 – 16below 12 or above 16
g/dLMale14 – 15.513 – 18below 13 or above 18
g/LFemale135 – 145120 – 160below 120 or above 160
g/LMale140 – 155130 – 180below 130 or above 180
mmol/LFemale8.4 – 97.4 – 9.9below 7.4 or above 9.9
mmol/LMale8.7 – 9.68.1 – 11.2below 8.1 or above 11.2

Interpretation: Sex-specific. The acceptable band starts where the WHO defines anaemia: below 12 g/dL (120 g/L) in non-pregnant women and below 13 g/dL (130 g/L) in men. The upper edges, 16 g/dL in women and 18 g/dL in men, are published laboratory limits; laboratories differ by up to 1 g/dL here. Where the client's sex is not recorded, the women's lower edge and the men's upper edge are used. Altitude, smoking and plasma volume all shift haemoglobin independently of iron status. The narrower optimal band has no published source behind it.

Sources

  • British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults — Snook J, Bhala N, Beales ILP, et al. — Gut, 2021 · Clinical guidelineStates the WHO definition of anaemia: haemoglobin below 130 g/L in men and below 120 g/L in non-pregnant women. This is the lower edge of the sufficient band for each sex. Full text read through Europe PMC (PMC8515119).
  • CBC blood test — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2024 · Government / public-health guidanceNormal haemoglobin is 13 to 18 g/dL in men and 12 to 16 g/dL in women. The women's row is Sera's band exactly; the men's row is the proposed band.
  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult haemoglobin 130 to 180 g/L in men and 115 to 165 g/L in women. Supports the men's 13 to 18 g/dL; its women's interval sits 0.5 g/dL either side of Sera's.
  • Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceHaemoglobin 130 to 180 g/L in men and 120 to 160 g/L in women, the same numbers as the proposed bands. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.
  • Hemoglobin — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2026 · Government / public-health guidanceA narrower adult interval on the dedicated MedlinePlus page: 13.8 to 17.2 g/dL in men and 12.1 to 15.1 g/dL in women (reviewed February 2026). Shows that published upper limits for women range from 15.1 to 16.5.
  • Haemoglobin thresholds to define anaemia from age 6 months to 65 years: estimates from international data sources — Braat S, Fielding KL, Han J, et al. — The Lancet Haematology, 2024 · Peer-reviewed publicationPooled healthy reference samples from eight countries, including the USA, England, Canada and the Netherlands: the fifth centile of haemoglobin was 119.7 g/L in non-pregnant women and 134.9 g/L in men aged 18 to 65. Confirms 120 g/L for women and suggests the men's threshold could be 135 rather than 130.

Last reviewed: November 9, 2026 · Hemoglobin on its own page

Hematocrit (HCT)Established clinical thresholdSex-specific% · L/L

The share of your blood that is made up of red blood cells.

UnitApplies toOptimalSufficientOut of range
%Female37 – 4436 – 48below 36 or above 48
%Male40 – 4640 – 52below 40 or above 52
L/LFemale0.37 – 0.440.36 – 0.48below 0.36 or above 0.48
L/LMale0.4 – 0.460.4 – 0.52below 0.4 or above 0.52

Interpretation: Sex-specific. The acceptable band ends where the British Society for Haematology says a persistently raised haematocrit should be investigated: above 0.48 in women and above 0.52 in men. The lower edges, 36% in women and 40% in men, are published laboratory limits; some laboratories set them 2 to 3 points lower. Where the client's sex is not recorded, the women's lower edge and the men's upper edge are used. Dehydration, altitude and smoking raise haematocrit. The narrower optimal band has no published source behind it.

Sources

  • CBC blood test — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2024 · Government / public-health guidanceNormal haematocrit is 40% to 55% in men and 36% to 48% in women. The women's row is Sera's band exactly; the men's lower limit of 40% is the proposed edge.
  • A guideline for the diagnosis and management of polycythaemia vera. A British Society for Haematology Guideline — McMullin MF, Harrison CN, Ali S, et al. — British Society for Haematology (author manuscript in the Oxford University Research Archive; published in British Journal of Haematology), 2019 · Clinical guidelineA persistently raised venous haematocrit above 0.52 in men or 0.48 in women should be investigated. These are the upper edges of the sufficient band for each sex. Read in the author manuscript held by the Oxford University Research Archive.
  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult haematocrit 0.40 to 0.54 L/L in men and 0.37 to 0.47 L/L in women. Supports 0.40 as the men's lower limit.
  • Hematocrit — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2026 · Government / public-health guidanceThe dedicated MedlinePlus page gives lower intervals: 37% to 48% in men and 34% to 43% in women (reviewed February 2026). Shows how far published limits differ; a men's lower limit of 37% would sit below the proposed 40%.
  • Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceHaematocrit 0.38 to 0.51 L/L in men and 0.34 to 0.47 L/L in women. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.

Last reviewed: November 9, 2026 · Hematocrit on its own page

Mean Corpuscular Volume (MCV)Published reference intervalfL

The average size of your red blood cells.

UnitOptimalSufficientOut of range
fL85 – 9280 – 100below 80 or above 100

Interpretation: The acceptable band of 80 to 100 fL is the standard adult reference interval: below 80 is microcytic (most often iron deficiency or thalassaemia trait) and above 100 is macrocytic (most often B12 or folate deficiency, alcohol or liver disease). The optimal band of 85 to 92 fL is a functional-practice target with no published source behind it.

Sources

  • CBC blood test — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2024 · Government / public-health guidanceNormal MCV is 80 to 100 femtolitres, Sera's sufficient band exactly.
  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult mean cell volume 80 to 100 fL, Sera's sufficient band exactly.
  • RBC indices — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2026 · Government / public-health guidanceA second MedlinePlus page gives 79 to 95 fL (reviewed February 2026). Its upper limit is 5 fL below Sera's, so published limits are not uniform.

Last reviewed: November 9, 2026 · MCV on its own page

Mean Corpuscular Hemoglobin (MCH)Published reference intervalpg

The average amount of hemoglobin in each red blood cell.

UnitOptimalSufficientOut of range
pg28 – 3227 – 33below 27 or above 33

Interpretation: The acceptable band of 27 to 33 pg is a published adult reference interval; some laboratories end it at 32. MCH moves with MCV: low values go with small, pale cells (iron deficiency, thalassaemia trait), high values with large cells. The optimal band of 28 to 32 pg has no published source behind it.

Sources

  • RBC indices — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2026 · Government / public-health guidanceNormal MCH is 27 to 33 pg per cell in men and 26 to 33 in women (reviewed February 2026). The men's figure is Sera's sufficient band exactly.
  • Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceMean cell haemoglobin 27 to 33 pg for both sexes, Sera's sufficient band exactly. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.
  • CBC blood test — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2024 · Government / public-health guidanceA second MedlinePlus page gives 27 to 32 pg per cell. Same lower limit; upper limit 1 pg below Sera's.
  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult mean cell haemoglobin 27 to 32 pg.

Last reviewed: November 9, 2026 · MCH on its own page

Mean Corpuscular Hemoglobin Concentration (MCHC)Published reference intervalg/dL · g/L · %

The average concentration of hemoglobin inside your red blood cells.

UnitOptimalSufficientOut of range
g/dL33 – 3532 – 36below 32 or above 36
g/L330 – 350320 – 360below 320 or above 360
%33 – 3532 – 36below 32 or above 36

Interpretation: The acceptable band of 32 to 36 g/dL (320 to 360 g/L) is the standard adult reference interval. Low values go with iron deficiency and thalassaemia; a high value is uncommon and is often a sample artefact (haemolysis, lipaemia, cold agglutinins) or spherocytosis. The optimal band of 33 to 35 g/dL has no published source behind it.

Sources

  • RBC indices — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2026 · Government / public-health guidanceNormal MCHC is 32 to 36 g/dL, or 320 to 360 g/L (reviewed February 2026). Sera's sufficient band exactly, in both units.
  • CBC blood test — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2024 · Government / public-health guidanceNormal MCHC is 32 to 36 g/dL.
  • Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceMCHC 320 to 370 g/L. Same lower limit; upper limit 10 g/L above Sera's. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.

Last reviewed: November 9, 2026 · MCHC on its own page

RDW (Red Cell Distribution Width)Published reference interval%

A measure of how much your red blood cells vary in size. A higher number means they are more uneven.

UnitOptimalSufficientOut of range
%11.5 – 12.511 – 14.5below 11 or above 14.5

Interpretation: The acceptable band of 11.0 to 14.5% is the adult interval of the University of Washington laboratory; an NHS laboratory uses 11.5 to 15.7%, so the upper limit depends on the analyser. MedlinePlus says a low RDW is not a sign of anaemia. The optimal band of 11.5 to 12.5% is a functional target: cohort data link a higher RDW to higher mortality without fixing a percentage.

Sources

  • RDW CV | Laboratory Test Guide — Department of Laboratory Medicine & Pathology, UW Medicine (University of Washington), 2022 · Laboratory / reference-interval sourceReference range for RDW-CV from age 6 years, both sexes: 11.0 to 14.5% (effective September 2022). Sera's sufficient band exactly.
  • Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceRed cell distribution width 11.5 to 15.7% for both sexes. A wider interval than Sera's, showing the upper limit varies by analyser. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.
  • RDW (Red Cell Distribution Width) — U.S. National Library of Medicine (MedlinePlus Medical Tests), 2024 · Government / public-health guidanceA low RDW means the red cells are similar in size; it is not a sign of anaemia and is not usually a concern. The page gives no numbers and says reference ranges vary by laboratory. Supports not flagging a low result.
  • The relationship between red cell distribution width and all-cause and cause-specific mortality in a general population — Pan J, Borné Y, Engström G — Scientific Reports, 2019 · Peer-reviewed publicationIn 27,063 Swedish adults followed for about 20 years, the highest quarter of RDW had 34% higher all-cause mortality than the lowest. RDW was measured as RDW-SD in fL, so the study supports 'lower is better' but not Sera's 12.5% edge.

Last reviewed: November 9, 2026 · RDW on its own page

WBC # (White Blood Cell Count)Published reference interval×10⁹/L · ×10³/μL · K/μL · /mm³ · x E9/L

The total number of white blood cells in your blood.

UnitOptimalSufficientOut of range
×10⁹/L5 – 7.54 – 11below 4 or above 11
×10³/μL5 – 7.54 – 11below 4 or above 11
K/μL5 – 7.54 – 11below 4 or above 11
/mm³5,000 – 7,5004,000 – 11,000below 4,000 or above 11,000
x E9/L5 – 7.54 – 11below 4 or above 11

Interpretation: The acceptable band of 4 to 11 ×10⁹/L is a published adult reference interval; laboratories set the lower limit anywhere from 3.6 to 4.5. The optimal band of 5 to 7.5 is a functional target with partial support: in a cohort of 686,475 English adults, deaths were fewest at 5.35 to 6.25 and half as common again at 8.65 to 10.05 as at 6.25 to 7.25, although still inside the reference interval. People of African or Middle Eastern ancestry often have a lower normal count.

Sources

  • Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceWhite blood cell count 4.0 to 11.0 ×10⁹/L for both sexes, Sera's sufficient band exactly. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.
  • WBC count — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2025 · Government / public-health guidanceNormal white cell count is 4,500 to 11,000 per microlitre (4.5 to 11.0 ×10⁹/L); below 4.5 is called below normal. Same upper edge as Sera; lower edge 0.5 higher.
  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult total white cell count 3.6 to 11.0 ×10⁹/L. Same upper edge as Sera; lower edge 0.4 lower.
  • White cell count in the normal range and short-term and long-term mortality: international comparisons of electronic health record cohorts in England and New Zealand — Shah AD, Thornley S, Chung SC, Denaxas S, Jackson R, Hemingway H — BMJ Open, 2017 · Peer-reviewed publicationIn 686,475 English adults aged 30 to 75, mortality was lowest at a white cell count of 5.35 to 6.25 ×10⁹/L, and 51% higher at 8.65 to 10.05 than at 6.25 to 7.25. Supports an optimal band sitting in the lower-middle of the reference interval; Sera's 5 and 7.5 are close to, not equal to, these quintile edges. Full text read through Europe PMC (PMC5318564).

Last reviewed: November 9, 2026 · White blood cell count on its own page

Neutrophils #Published reference interval×10⁹/L · ×10³/μL · K/μL · /mm³ · x E9/L

The number of neutrophils, the most common type of white blood cell.

UnitOptimalSufficientOut of range
×10⁹/L2.5 – 51.8 – 7.5below 1.8 or above 7.5
×10³/μL2.5 – 51.8 – 7.5below 1.8 or above 7.5
K/μL2.5 – 51.8 – 7.5below 1.8 or above 7.5
/mm³2,500 – 5,0001,800 – 7,500below 1,800 or above 7,500
x E9/L2.5 – 51.8 – 7.5below 1.8 or above 7.5

Interpretation: The acceptable band of 1.8 to 7.5 ×10⁹/L is a published laboratory reference interval. Neutropenia is defined lower, below 1.5, so a result of 1.5 to 1.8 is under the interval but is not neutropenia. Counts of 1.0 to 1.5 are normal for many people of African, Arab or West Indian ancestry (the Duffy-null phenotype). A raised count most often reflects infection, inflammation, smoking, steroids or stress. The optimal band of 2.5 to 5 has no published source behind it.

Sources

  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult neutrophils 1.8 to 7.5 ×10⁹/L, Sera's sufficient band exactly.
  • Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceNeutrophils 1.9 to 8.0 ×10⁹/L for both sexes, close to Sera's band. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.
  • Neutropenia — Mithoowani S, Cameron L, Crowther MA — CMAJ (Canadian Medical Association Journal), 2022 · Peer-reviewed publicationNeutropenia is graded mild at 1.0 to 1.5 ×10⁹/L, moderate at 0.5 to 0.9 and severe below 0.5; the reference interval is specific to the population, and mild neutropenia is common with the Duffy-null phenotype. A result between 1.5 and 1.8 is below Sera's band but is not neutropenia. Full text read through Europe PMC (PMC9829051).

Last reviewed: November 9, 2026 · Neutrophil count on its own page

Lymphocytes #Published reference interval×10⁹/L · ×10³/μL · K/μL · /mm³ · x E9/L

The number of lymphocytes, the white blood cells behind your long-term, targeted immunity.

UnitOptimalSufficientOut of range
×10⁹/L1.5 – 31 – 4below 1 or above 4
×10³/μL1.5 – 31 – 4below 1 or above 4
K/μL1.5 – 31 – 4below 1 or above 4
/mm³1,500 – 3,0001,000 – 4,000below 1,000 or above 4,000
x E9/L1.5 – 31 – 4below 1 or above 4

Interpretation: The acceptable band of 1.0 to 4.0 is the adult reference interval used by NHS and US laboratories. The optimal band starts at 1.5 because, in a large US cohort, counts of 1,500 per microlitre or less were linked to higher mortality; a Danish cohort placed that risk below 1.1. The optimal ceiling of 3.0 is a functional target with no outcome evidence behind it. Lymphocytes rise with viral infections and fall with illness and some medications, so the count is read alongside the total white cell count, and a trend matters more than a single value.

Sources

  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult lymphocytes 1.0 to 4.0 ×10⁹/L, the same as Sera's sufficient band.
  • White Blood Count — North Bristol NHS Trust, Severn Pathology, 2026 · Laboratory / reference-interval sourceAdult lymphocytes 1.0 to 4.0 ×10⁹/L, the same as Sera's sufficient band. The page shows no review date; 2026 is the footer year.
  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (15 years and older) absolute lymphocytes 1.0 to 4.0 ×10³/μL, the same as Sera's sufficient band. The page shows no review date; 2026 is the copyright year.
  • Association of Lymphopenia With Risk of Mortality Among Adults in the US General Population — Zidar DA, Al-Kindi SG, Liu Y, et al. — JAMA Network Open, 2019 · Peer-reviewed publicationIn 31,178 US adults (NHANES), a lymphocyte count of 1500/μL or less carried an age- and sex-adjusted mortality hazard ratio of 1.3, and 1000/μL or less a ratio of 1.8. This matches Sera's optimal lower edge of 1.5 and sufficient lower edge of 1.0.
  • Incidental lymphopenia and mortality: a prospective cohort study — Warny M, Helby J, Nordestgaard BG, Birgens H, Bojesen SE — CMAJ, 2020 · Peer-reviewed publicationIn 108,135 Danish adults, a lymphocyte count below 1.1 ×10⁹/L carried an all-cause mortality hazard ratio of 1.63 against the reference range of 1.1 to 3.7. This supports flagging counts near Sera's sufficient lower edge of 1.0; it does not support an optimal ceiling of 3.0.
  • FBC — University Hospitals Sussex NHS Foundation Trust, Pathology, 2022 · Laboratory / reference-interval sourceAdult lymphocytes 1.0 to 3.0 ×10⁹/L. One laboratory's reference interval ends where Sera's optimal band ends; this is a reference limit, not an outcome target.

Last reviewed: November 9, 2026 · Lymphocyte count on its own page

Monocytes #Published reference interval×10⁹/L · ×10³/μL · K/μL · /mm³ · x E9/L

The number of monocytes, large white blood cells that fight long-term infections.

UnitOptimalSufficientOut of range
×10⁹/L0.2 – 0.60.1 – 0.8below 0.1 or above 0.8
×10³/μL0.2 – 0.60.1 – 0.8below 0.1 or above 0.8
K/μL0.2 – 0.60.1 – 0.8below 0.1 or above 0.8
/mm³200 – 600100 – 800below 100 or above 800
x E9/L0.2 – 0.60.1 – 0.8below 0.1 or above 0.8

Interpretation: The acceptable band's upper edge of 0.8 ×10⁹/L is the adult upper limit at two NHS laboratories; others use 1.0. Its lower edge of 0.1 matches no source: the NHS laboratories checked use 0.2. The optimal band of 0.2 to 0.6 has no outcome evidence behind it.

Sources

  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult monocytes 0.2 to 0.8 ×10⁹/L. Matches Sera's sufficient upper edge of 0.8; the lower limit is 0.2, not Sera's 0.1.
  • Full blood count (FBC) — Black Country Pathology Services (NHS), 2026 · Laboratory / reference-interval sourceAdult monocytes 0.2 to 0.8 ×10⁹/L. Matches Sera's sufficient upper edge of 0.8; the lower limit is 0.2, not Sera's 0.1. The page shows no review date; 2026 is the footer year.
  • White Blood Count — North Bristol NHS Trust, Severn Pathology, 2026 · Laboratory / reference-interval sourceAdult monocytes 0.2 to 1.0 ×10⁹/L. Same lower limit of 0.2; a wider upper limit than Sera's 0.8. The page shows no review date; 2026 is the footer year.
  • FBC — University Hospitals Sussex NHS Foundation Trust, Pathology, 2022 · Laboratory / reference-interval sourceAdult monocytes 0.2 to 1.0 ×10⁹/L. Same lower limit of 0.2; a wider upper limit than Sera's 0.8.
  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult absolute monocytes 0.05 to 0.6 ×10³/μL. Its upper limit equals Sera's optimal upper edge of 0.6; its lower limit of 0.05 is below every Sera edge. The page shows no review date; 2026 is the copyright year.

Last reviewed: November 9, 2026 · Monocyte count on its own page

Eosinophils #Established clinical thresholdOne-sided×10⁹/L · ×10³/μL · K/μL · /mm³ · x E9/L

The number of eosinophils, white blood cells that fight parasites and drive allergic reactions.

UnitOptimalSufficientOut of range
×10⁹/L0.05 – 0.30.02 – 0.5above 0.5
×10³/μL0.05 – 0.30.02 – 0.5above 0.5
K/μL0.05 – 0.30.02 – 0.5above 0.5
/mm³50 – 30020 – 500above 500
x E9/L0.05 – 0.30.02 – 0.5above 0.5

Bounded on the high side only — a low result is not treated as out of range. Most laboratories and medlineplus start the normal interval at zero and no source defines a low eosinophil threshold.

Interpretation: The acceptable band ends at 0.5, the level above which a count is conventionally called eosinophilia (500 cells per microlitre). A low eosinophil count has no accepted threshold: most laboratories start the normal interval at zero. The optimal ceiling of 0.3 is a functional target with no outcome evidence found. Eosinophils rise with allergies, asthma and parasitic infections and vary with allergic activity, so the count is read alongside the total white cell count, and a trend matters more than a single value.

Sources

  • Eosinophil count - absolute — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceA normal eosinophil count is less than 500 cells per microlitre, with no lower limit. Matches Sera's sufficient upper edge of 0.5 ×10⁹/L.
  • Eosinophilia — NHS Dumfries and Galloway, DGRefHelp (Right Decisions, NHS Scotland), 2024 · Clinical guidelineThe normal range for eosinophils is 0.0 to 0.5 ×10⁹/L and eosinophilia is a count above 0.5; persistent counts of 1.5 or more are referred. Matches Sera's sufficient upper edge and gives no lower limit.
  • White Blood Count — North Bristol NHS Trust, Severn Pathology, 2026 · Laboratory / reference-interval sourceAdult eosinophils 0.0 to 0.5 ×10⁹/L. Matches Sera's sufficient upper edge; the lower limit is zero. The page shows no review date; 2026 is the footer year.
  • FBC — University Hospitals Sussex NHS Foundation Trust, Pathology, 2022 · Laboratory / reference-interval sourceAdult eosinophils 0 to 0.5 ×10⁹/L. Matches Sera's sufficient upper edge; the lower limit is zero.
  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult absolute eosinophils 0.05 to 0.5 ×10³/μL. The upper limit matches Sera's sufficient edge; its lower limit of 0.05 equals Sera's optimal lower edge, as one laboratory's reference limit. The page shows no review date; 2026 is the copyright year.

Last reviewed: November 9, 2026 · Eosinophil count on its own page

Basophils #Published reference intervalOne-sided×10⁹/L · ×10³/μL · K/μL · /mm³ · x E9/L

The number of basophils, the rarest white blood cells, which take part in inflammation and allergic reactions.

UnitOptimalSufficientOut of range
×10⁹/L0.02 – 0.080.01 – 0.1above 0.1
×10³/μL0.02 – 0.080.01 – 0.1above 0.1
K/μL0.02 – 0.080.01 – 0.1above 0.1
/mm³20 – 8010 – 100above 100
x E9/L0.02 – 0.080.01 – 0.1above 0.1

Bounded on the high side only — a low result is not treated as out of range. Most laboratories start the basophil interval at zero and no source defines a low basophil threshold.

Interpretation: The acceptable band ends at 0.1, the adult upper reference limit at most laboratories checked; one NHS laboratory uses 0.2. Basophils are normally so few that a low count has no accepted meaning, and most laboratories start the interval at zero. The optimal ceiling of 0.08 has no published source. The count is interpreted mainly when it is persistently raised, alongside the total white cell count, and a trend matters more than a single value.

Sources

  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult basophils 0.02 to 0.10 ×10⁹/L. Matches Sera's sufficient upper edge of 0.1; its lower limit of 0.02 equals Sera's optimal lower edge.
  • FBC — University Hospitals Sussex NHS Foundation Trust, Pathology, 2022 · Laboratory / reference-interval sourceAdult basophils 0 to 0.1 ×10⁹/L. Matches Sera's sufficient upper edge; the lower limit is zero.
  • Full blood count (FBC) — Black Country Pathology Services (NHS), 2026 · Laboratory / reference-interval sourceAdult basophils 0 to 0.1 ×10⁹/L. Matches Sera's sufficient upper edge; the lower limit is zero. The page shows no review date; 2026 is the footer year.
  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult absolute basophils 0.0 to 0.1 ×10³/μL. Matches Sera's sufficient upper edge; the lower limit is zero. The page shows no review date; 2026 is the copyright year.

Last reviewed: November 9, 2026 · Basophil count on its own page

Neutrophils %Published reference interval%

The share of your white blood cells that are neutrophils.

UnitOptimalSufficientOut of range
%45 – 6540 – 70below 40 or above 70

Interpretation: The acceptable band starts at 40%, the lower reference limit MedlinePlus gives. Its upper edge of 70% is not a published limit: MedlinePlus ends at 60% and a US laboratory catalogue at 80%. The optimal band of 45% to 65% has no published source. A percentage shifts whenever another cell type changes, so the absolute neutrophil count is the more meaningful figure and the two are read together with the total white cell count.

Sources

  • Blood differential test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal neutrophils are 40% to 60% of white cells. Matches Sera's sufficient lower edge of 40; its upper limit of 60 is below Sera's 70.
  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult neutrophils 50% to 80%. A wider and higher interval than Sera's: its upper limit of 80 is above Sera's 70 and its lower limit of 50 is above Sera's 40. The page shows no review date; 2026 is the copyright year.

Last reviewed: November 9, 2026 · Neutrophil percentage on its own page

Lymphocytes %Published reference interval%

The share of your white blood cells that are lymphocytes.

UnitOptimalSufficientOut of range
%25 – 3520 – 40below 20 or above 40

Interpretation: The acceptable band of 20% to 40% is the reference interval MedlinePlus gives; some laboratories use a wider one. The optimal band of 25% to 35% has no published source. A percentage shifts whenever another cell type changes, so the absolute lymphocyte count is the more meaningful figure and the two are read together with the total white cell count.

Sources

  • Blood differential test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal lymphocytes are 20% to 40% of white cells, the same as Sera's sufficient band.
  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult lymphocytes 10% to 50%, a wider interval than Sera's 20% to 40%. The page shows no review date; 2026 is the copyright year.

Last reviewed: November 9, 2026 · Lymphocyte percentage on its own page

Monocytes %Published reference interval%

The share of your white blood cells that are monocytes.

UnitOptimalSufficientOut of range
%3 – 72 – 8below 2 or above 8

Interpretation: The acceptable band of 2% to 8% is the reference interval MedlinePlus gives. Laboratories differ widely here, and some print an interval as high as 5% to 15%, so the laboratory's own range should be checked before a result just above 8% is treated as raised. The optimal band of 3% to 7% has no published source. The absolute monocyte count is the more meaningful figure, since a percentage shifts whenever another cell type changes.

Sources

  • Blood differential test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal monocytes are 2% to 8% of white cells, the same as Sera's sufficient band.
  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult monocytes 5% to 15%, a higher interval than Sera's 2% to 8%. The page shows no review date; 2026 is the copyright year.

Last reviewed: November 9, 2026 · Monocyte percentage on its own page

Eosinophils %Published reference interval%

The share of your white blood cells that are eosinophils.

UnitOptimalSufficientOut of range
%1 – 31 – 4below 1 or above 4

Interpretation: The acceptable band of 1% to 4% is the reference interval MedlinePlus gives; some laboratories use 0% to 8%. The optimal ceiling of 3% has no published source. A result below 1% has no accepted clinical meaning on its own. The absolute eosinophil count is the more meaningful figure, since a percentage shifts whenever another cell type changes; it rises with allergic activity and certain infections.

Sources

  • Blood differential test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal eosinophils are 1% to 4% of white cells, the same as Sera's sufficient band.
  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult eosinophils 0% to 8%: no lower limit, and an upper limit twice Sera's 4%. The page shows no review date; 2026 is the copyright year.

Last reviewed: November 9, 2026 · Eosinophil percentage on its own page

Basophils %Published reference interval%

The share of your white blood cells that are basophils.

UnitOptimalSufficientOut of range
%0 – 0.50 – 1below 0 or above 1

Interpretation: The acceptable band of 0% to 1% is a published laboratory reference interval. The optimal ceiling of 0.5% has no published source; MedlinePlus gives 0.5% to 1% as normal. The percentage is normally small and is interpreted mainly when persistently raised, and the absolute basophil count is the more meaningful figure.

Sources

  • AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult basophils 0% to 1%, the same as Sera's sufficient band. The page shows no review date; 2026 is the copyright year.
  • Blood differential test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal basophils are 0.5% to 1% of white cells. Matches Sera's sufficient upper edge of 1%; 0.5% is its lower limit, not an optimal ceiling.

Last reviewed: November 9, 2026 · Basophil percentage on its own page

Immature Granulocytes %Published reference interval%

Young white blood cells (metamyelocytes and myelocytes) released from the bone marrow before they are fully mature, as a percentage of all white cells.

UnitOptimalSufficientOut of range
%0 – 0.6—below 0 or above 0.6

No separate Sufficient band is currently defined for this marker.

Interpretation: Two US hospital laboratories print 0 to 0.5 % and 0 to 0.6 %; Sera uses 0.6. There is no low flag, since every interval starts at 0. Labcorp counts metamyelocytes and myelocytes, not band cells or blasts. No NHS trust page with an interval could be found. Infection, inflammation, pregnancy, surgery and steroid treatment raise it. No source supports a narrower optimal range.

Sources

Last reviewed: November 9, 2026 · Immature granulocytes on its own page

Platelets (Thrombocytes)Published reference interval×10⁹/L · ×10³/μL · K/μL · /mm³ · x E9/L

Tiny blood cells that help your blood clot.

UnitOptimalSufficientOut of range
×10⁹/L175 – 320150 – 400below 150 or above 400
×10³/μL175 – 320150 – 400below 150 or above 400
K/μL175 – 320150 – 400below 150 or above 400
/mm³175,000 – 320,000150,000 – 400,000below 150,000 or above 400,000
x E9/L175 – 320150 – 400below 150 or above 400

Interpretation: The acceptable band of 150 to 400 ×10⁹/L is the conventional adult reference interval, as given by MedlinePlus. The optimal lower edge of 175 matches a Danish cohort of 21,252 adults in which mortality was higher below it; the same cohort found higher mortality above 300, where the optimal band here runs to 320.

Sources

  • Platelet count — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2025 · Government / public-health guidanceNormal adult platelet count is 150,000 to 400,000 per microlitre, or 150 to 400 ×10⁹/L. This matches Sera's sufficient band exactly.
  • Platelet count is associated with cardiovascular disease, cancer and mortality: A population-based cohort study — Vinholt PJ, Hvas AM, Frederiksen H, et al. — Thrombosis Research, 2016 · Peer-reviewed publicationDanish general-population cohort of 21,252 adults. Against a reference group of 201 to 250 ×10⁹/L, mortality was higher below 175 and above 300. Supports the optimal lower edge of 175 and an upper edge of 300 rather than 320.
  • Complete Blood Cell Count (CBC) with Differential, Blood (Test ID CBC) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult platelet reference values are 135 to 317 ×10⁹/L in men and 157 to 371 in women. A sex-specific interval that is narrower than Sera's sufficient band at the top.
  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult platelet count 140 to 400 ×10⁹/L. Supports the sufficient upper edge of 400.

Last reviewed: November 9, 2026 · Platelet count on its own page

Mean Platelet Volume (MPV)No universal rangeUnbandedfL · unbanded

The average size of the platelets in circulation, reported alongside the platelet count on any full blood count.

No universal Sera range published.

Analysers disagree on the scale, and no published interval holds across them. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Interpretable only alongside the platelet count: a high MPV with a low count suggests platelets are being consumed and replaced, while a high MPV with a normal count reflects greater platelet reactivity. It drifts upward in EDTA the longer a sample waits, so a modest isolated elevation on a delayed sample is often pre-analytical. MPV is not standardised between analysers: published European intervals on Sysmex instruments run from about 9 to 13 fL, while impedance analysers report roughly 2 fL lower. Read the result against the reporting laboratory's own interval.

Sources

Last reviewed: November 9, 2026

PDW (Platelet Distribution Width)No universal rangeUnbandedAssay-dependentfL · % · unbanded

How much platelet size varies within a sample, reported alongside the count and the mean volume.

No universal Sera range published.

The one published interval is specific to a single analyser, and the fL and % scales are not interchangeable. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Read with MPV and the platelet count, never alone: a wide distribution alongside a high MPV suggests the marrow is releasing platelets of mixed age. The fL and % rows are different measurements — the percentage is a coefficient of variation — and are not interchangeable. PDW is calculated differently by each analyser, so the reporting laboratory's interval is the one to use; the only European interval found is 9.3 to 17.3 fL on a Sysmex analyser.

Sources

Last reviewed: November 9, 2026

PCT (Plateletcrit)Published reference interval% · L/L

The fraction of blood volume occupied by platelets — the platelet equivalent of the haematocrit.

UnitOptimalSufficientOut of range
%0.15 – 0.350.1 – 0.4below 0.1 or above 0.4
L/L0.002 – 0.0040.001 – 0.004below 0.001 or above 0.004

Interpretation: The product of count and mean volume, so it captures total platelet mass rather than number. Most useful when count and MPV move in opposite directions and it is not obvious what happened to the total. Not procalcitonin, which shares the abbreviation and is a different test entirely. The optimal band is close to a UK reference interval measured on a Sysmex analyser (0.16 to 0.35% in men, 0.18 to 0.37% in women). The wider acceptable band has no published source, and because plateletcrit depends on the analyser's MPV, the reporting laboratory's interval takes precedence.

Sources

Last reviewed: November 9, 2026 · Plateletcrit on its own page

Reticulocytes (Absolute)Published reference interval×10⁹/L · ×10³/μL · K/μL · /mm³ · x E9/L

The number of brand-new red blood cells in circulation, counted directly. This is the more reliable of the two reticulocyte measures.

UnitOptimalSufficientOut of range
×10⁹/L30 – 110—below 30 or above 110
×10³/μL30 – 110—below 30 or above 110
K/μL30 – 110—below 30 or above 110
/mm³30,000 – 110,000—below 30,000 or above 110,000
x E9/L30 – 110—below 30 or above 110

No separate Sufficient band is currently defined for this marker.

Interpretation: The band is the adult laboratory reference interval (Mayo Clinic Laboratories: 30.4 to 110.9 ×10⁹/L). It is a reference interval, not an outcome-based target, and it only means something read against the haemoglobin: a count inside the band is an inadequate marrow response when the client is anaemic.

Sources

  • Reticulocyte Profile, Blood (Test ID RETB) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult absolute reticulocyte reference values are 30.4 to 110.9 ×10⁹/L. This matches Sera's band of 30 to 110.

Last reviewed: November 9, 2026 · Reticulocyte count on its own page

Reticulocytes (%)Published reference interval%

Brand-new red blood cells as a percentage of all your red blood cells.

UnitOptimalSufficientOut of range
%0.5 – 2.5—below 0.5 or above 2.5

No separate Sufficient band is currently defined for this marker.

Interpretation: The band reflects published adult laboratory reference intervals, which range from 0.5 to 2.0% (Gloucestershire Hospitals NHS) to 0.60 to 2.71% (Mayo Clinic Laboratories). The percentage depends on the red cell count, so in anaemia it overstates marrow output; the absolute count is the more reliable figure.

Sources

  • Reticulocyte Profile, Blood (Test ID RETB) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reticulocyte percentage reference values are 0.60 to 2.71%. Close to Sera's band of 0.5 to 2.5%.
  • Reticulocyte count — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2026 · Government / public-health guidanceA normal result in healthy adults who are not anaemic is 0.77% to 2.26%. Narrower than Sera's band of 0.5 to 2.5%.
  • Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceReticulocyte count 0.5 to 2.0% for adults and children. Matches Sera's lower edge of 0.5%.

Last reviewed: November 9, 2026 · Reticulocyte percentage on its own page

FerritinEstablished clinical thresholdSex-specificng/mL · μg/L · pmol/L

The protein that stores iron and shows how much iron your body has in reserve.

UnitApplies toOptimalSufficientOut of range
ng/mLFemale50 – 15030 – 200below 30 or above 200
ng/mLMale50 – 15030 – 300below 30 or above 300
μg/LFemale50 – 15030 – 200below 30 or above 200
μg/LMale50 – 15030 – 300below 30 or above 300
pmol/LFemale112 – 33767 – 450below 67 or above 450
pmol/LMale112 – 33767 – 674below 67 or above 674

Interpretation: Ferritin is an acute-phase protein: inflammation raises it independently of iron stores, so a normal-looking ferritin can mask deficiency. Read alongside transferrin saturation and an inflammatory marker. The acceptable band starts at 30 ng/mL, where the American Society of Hematology (2026) diagnoses iron deficiency in adults; the WHO threshold of 15 is lower and more specific. The optimal band starts at 50, the ASH threshold for higher-risk groups such as people with heavy menstrual bleeding. With inflammation, ASH considers iron deficiency possible up to 100 ng/mL. The acceptable band ends where European liver guidelines prompt a check for iron overload when transferrin saturation is also raised: above 200 in women and above 300 in men. The optimal ceiling of 150 is a functional target with no outcome evidence behind it.

Sources

  • ASH Sets New Standards for Diagnosing Iron Deficiency — American Society of Hematology, 2026 · Professional societyASH's 2026 guideline diagnoses iron deficiency at a ferritin of 30 ng/mL or lower in adults, and 50 ng/mL or lower in higher-risk groups such as people with heavy menstrual bleeding. With inflammation, ferritin under 100 ng/mL or transferrin saturation under 20% may indicate deficiency. Matches Sera's sufficient floor of 30 and optimal floor of 50.
  • American Society of Hematology 2026 guidelines for diagnosis of iron deficiency — Powers JM, Lim MY, Achebe MO, et al. — Blood Advances, 2026 · Clinical guidelineThe guideline itself, open access. Suggests a ferritin threshold of 30 ng/mL or lower to diagnose iron deficiency in adults, including menstruating people; 50 ng/mL or lower for people with symptoms or ongoing risk factors such as heavy menstrual bleeding; and, in adults with anaemia of inflammation, a ferritin under 100 ng/mL or transferrin saturation under 20%. These are the edges Sera's ferritin bands follow.
  • British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults — Snook J, Bhala N, Beales ILP, et al. — Gut, 2021 · Clinical guidelineFerritin below 15 µg/L indicates absent iron stores and below 30 µg/L generally indicates low stores; a 45 µg/L cut-off is suggested as the best trade-off, and a value above 150 µg/L is unlikely with absolute iron deficiency. Supports the sufficient floor of 30.
  • EASL Clinical Practice Guidelines on haemochromatosis — European Association for the Study of the Liver — Journal of Hepatology, 2022 · Clinical guidelineTesting for haemochromatosis is prompted by ferritin above 200 µg/L with transferrin saturation above 45% in females, and ferritin above 300 µg/L with saturation above 50% in males and postmenopausal women. Supports a ceiling of 200 for women and 300 for men.
  • Ferritin blood test — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2026 · Government / public-health guidanceNormal ferritin range is 30 to 400 ng/mL in males and 13 to 150 ng/mL in females. Shows that laboratory intervals are sex-specific and that the male interval extends well above 200.
  • WHO Guideline on Use of Ferritin Concentrations to Assess Iron Status — World Health Organization, 2020 · Government / public-health guidanceIron deficiency in adults below 15 µg/L, and that inflammation raises ferritin independently of iron stores. Sera's higher floor is a practitioner target, not a WHO figure.

Last reviewed: November 9, 2026 · Ferritin on its own page

Iron (Serum)Published reference intervalSex-specificμg/dL · μmol/L · mg/dL

The amount of iron moving around in your blood.

UnitApplies toOptimalSufficientOut of range
μg/dLFemale85 – 13037 – 145below 37 or above 145
μg/dLMale85 – 13059 – 158below 59 or above 158
μmol/LFemale15.2 – 23.36.6 – 25.9below 6.6 or above 25.9
μmol/LMale15.2 – 23.310.6 – 28.3below 10.6 or above 28.3
mg/dLFemale0.085 – 0.130.037 – 0.145below 0.037 or above 0.145
mg/dLMale0.085 – 0.130.059 – 0.158below 0.059 or above 0.158

Interpretation: The acceptable band follows published laboratory reference intervals: 59 to 158 µg/dL in men and 37 to 145 in women (MedlinePlus), with some UK laboratories using one interval of 11 to 32 µmol/L for everyone. Where the client's sex is not recorded, 60 to 170 µg/dL is used. The optimal band of 85 to 130 µg/dL has no published source. Serum iron varies through the day and falls with infection and inflammation, so read it with ferritin and transferrin saturation, not alone.

Sources

  • Serum iron test — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2026 · Government / public-health guidanceNormal serum iron is 59 to 158 µg/dL (10.6 to 28.3 µmol/L) in males and 37 to 145 µg/dL (6.6 to 25.9 µmol/L) in females. The male lower limit matches Sera's 60; the female limit is much lower.
  • Iron and Total Iron-Binding Capacity, Serum (Test ID SFEC) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceSerum iron reference values are 50 to 150 µg/dL in males and 35 to 145 µg/dL in females. Confirms a sex-specific interval with a women's lower limit near 35.
  • Iron - Clinical Biochemistry — Oxford University Hospitals NHS Foundation Trust, 2025 · Laboratory / reference-interval sourceSerum iron reference range is 11 to 32 µmol/L for both sexes at all ages. Matches Sera's sufficient floor of 11 µmol/L and is close to its ceiling of 30.

Last reviewed: November 9, 2026 · Serum iron on its own page

TransferrinPublished reference intervalmg/dL · g/L · μmol/L

The protein that carries iron through your blood.

UnitOptimalSufficientOut of range
mg/dL200 – 360170 – 370below 170 or above 370
g/L2 – 3.61.7 – 3.7below 1.7 or above 3.7
μmol/L25.1 – 45.221.4 – 46.5below 21.4 or above 46.5

Interpretation: Both bands are laboratory reference intervals: 200 to 360 mg/dL is the Mayo Clinic Laboratories interval, and the wider acceptable band is close to UK adult intervals of about 1.7 to 3.8 g/L. Neither is an outcome-based target. Transferrin rises in iron deficiency, in pregnancy and with oral contraceptives, and falls with inflammation, liver disease, malnutrition and protein loss, so a low value is not evidence of iron overload on its own.

Sources

  • Transferrin, Serum (Test ID TRSF) — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceSerum transferrin reference values are 200 to 360 mg/dL, with no split by age or sex. This is exactly Sera's optimal band.
  • Transferrin — University Hospitals Birmingham NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdults aged 15 to 60: 1.74 to 3.64 g/L in men and 1.80 to 3.82 g/L in women (Abbott assay). Close to Sera's sufficient band of 1.7 to 3.7 g/L.
  • Transferrin — Leeds Teaching Hospitals NHS Trust, 2026 · Laboratory / reference-interval sourceReference range 2.0 to 3.2 g/L. Supports the optimal lower edge of 2.0 g/L and shows that some laboratories use a lower ceiling than Sera's.

Last reviewed: November 9, 2026 · Transferrin on its own page

TIBC (Total Iron Binding Capacity)Published reference intervalμg/dL · μmol/L · mg/dL

A measure of how much iron your blood is able to carry on transferrin.

UnitOptimalSufficientOut of range
μg/dL275 – 350250 – 400below 250 or above 400
μmol/L49.3 – 62.744.8 – 71.6below 44.8 or above 71.6
mg/dL0.275 – 0.350.25 – 0.4below 0.25 or above 0.4

Interpretation: Laboratories agree on a lower limit near 240 to 250 μg/dL and differ at the top: ARUP reports 240 to 450, and the interval commonly used by US laboratories is 250 to 450. Sera's upper edge of 400 follows the narrower interval some laboratories print. The optimal band of 275 to 350 is a functional target with no published source.

Sources

Last reviewed: November 9, 2026 · TIBC on its own page

Transferrin SaturationEstablished clinical thresholdSex-specific%

The share of transferrin that is currently carrying iron.

UnitApplies toOptimalSufficientOut of range
%Female25 – 3520 – 45below 20 or above 45
%Male25 – 3520 – 50below 20 or above 50

Interpretation: The acceptable band starts at 20%, the level below which guidelines for heart failure and kidney disease count iron as deficient, and ends where the European liver guideline starts to suspect iron overload: above 45% in women and above 50% in men and postmenopausal women. Where the client's sex is not recorded, 45% is used. Some laboratories accept down to 15% in women. The optimal band of 25 to 35% is a functional target: a Danish cohort found the lowest mortality at about 32 to 34%, but no study sets its edges. A fasting morning sample is needed, because saturation follows serum iron through the day.

Sources

Last reviewed: November 9, 2026 · Transferrin Saturation on its own page

UIBC (Unsaturated Iron Binding Capacity)Published reference intervalμg/dL · μmol/L

The share of your blood's iron-carrying capacity that is still empty. TIBC minus the iron already being carried.

UnitOptimalSufficientOut of range
μg/dL112 – 347—below 112 or above 347
μmol/L20 – 62—below 20 or above 62

No separate Sufficient band is currently defined for this marker.

Interpretation: UIBC is the part of transferrin's iron-carrying capacity that is still empty; it rises in iron deficiency and falls in iron overload and inflammation. The band, 112 to 347 µg/dL, sits within a few micrograms of the interval commonly used by US laboratories, 111 to 343. It is method-dependent, so the range printed on the client's report takes precedence. There is no guideline threshold and no evidence for a narrower optimal band; transferrin saturation and ferritin carry the clinical thresholds.

Sources

Last reviewed: November 9, 2026 · UIBC on its own page

Neutrophil-to-Lymphocyte Ratio (NLR)Exploratory indexAuto-calculated

The ratio of neutrophils to lymphocytes, a marker of inflammation and immune balance.

Auto-calculated

Neutrophils / Lymphocytes

Calculated when Neutrophils # and Lymphocytes # are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio1 – 20.78 – 3.53below 0.78 or above 3.53

Interpretation: There is no guideline threshold for NLR. The acceptable band is the range found in healthy Belgian adults aged 21 to 66, 0.78 to 3.53; a Dutch cohort aged 45 and over gave 0.83 to 3.92, and the ratio rises with age and runs higher in men. The optimal band ending at 2 is a functional target: in US and Dutch population cohorts mortality rose with higher NLR, clearly so from about 2.7, but no study sets a threshold at 2. The lower optimal edge of 1 has no evidence behind it. Observational and prognostic rather than diagnostic: acute infection, steroids and stress raise it for days.

Sources

Last reviewed: November 9, 2026

Monocyte-to-Lymphocyte Ratio (MLR)Exploratory indexAuto-calculatedratio

Absolute monocytes divided by absolute lymphocytes, from the full blood count.

Auto-calculated

Monocytes / Lymphocytes

Calculated when Monocytes # and Lymphocytes # are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio0.15 – 0.30.1 – 0.4below 0.1 or above 0.4

Interpretation: The monocyte arm of chronic immune activation, where NLR reads the neutrophil arm. Observational and prognostic rather than diagnostic. Monocytes are the least precisely counted cell in the differential, so a small movement here is more likely to be counting noise than the same movement in NLR would be. One European reference study gives a range of about 0.12 to 0.47 in women and 0.14 to 0.51 in men, wider at the top than the band here, so a result of 0.41 to 0.5 reads Out of range and is within that study's normal range.

Sources

Last reviewed: November 9, 2026

Neutrophil-to-Monocyte Ratio (NMR)No universal rangeAuto-calculatedUnbandedratio · unbanded

Absolute neutrophils divided by absolute monocytes, from the full blood count.

Auto-calculated

Neutrophils / Monocytes

Calculated when Neutrophils # and Monocytes # are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

No published reference interval was found for the ratio. Read this marker against the interval printed by the issuing laboratory.

Interpretation: Balances the two innate arms against each other rather than either against lymphocytes, so it moves for reasons NLR and MLR do not. The least established of the three: read it alongside them, and treat a change as a reason to look at the differential rather than as a finding in itself. No reference interval for healthy adults has been published and no band here has evidence behind it, so the value is shown without a status.

Sources

There is no band here to attribute to a source.

Last reviewed: November 9, 2026

Platelet-to-Lymphocyte Ratio (PLR)Exploratory indexAuto-calculated

The ratio of platelets to lymphocytes, a newer marker for inflammation and clotting risk.

Auto-calculated

Platelets / Lymphocytes

Calculated when Platelets (Thrombocytes) and Lymphocytes # are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio75 – 15050 – 200below 50 or above 200

Interpretation: The one European reference study, in Dutch adults aged 45 and over, gives a 95% interval of 61 to 239, tighter at the bottom and wider at the top than the band here. No guideline defines a normal PLR.

Sources

Last reviewed: November 9, 2026

Inflammation · 7 markers

Markers of systemic inflammation and immune activity

CRP (C-Reactive Protein, standard)Published reference intervalmg/L · mg/dL

The standard C-reactive protein test, which rises within hours of infection, injury or active inflammation.

UnitOptimalSufficientOut of range
mg/L0 – 5—below 0 or above 5
mg/dL0 – 0.5—below 0 or above 0.5

No separate Sufficient band is currently defined for this marker.

Interpretation: Standard CRP is a test for active inflammation or infection, not a cardiovascular risk figure. That is what hsCRP is for, and its cut-offs of 1 and 3 mg/L do not apply here. The band ends at 5 mg/L, the adult reference limit UK laboratories print. Labcorp prints 10 mg/L, so a result between 5 and 10 can be normal on a US report and is flagged here. Below 5 mg/L does not exclude low-grade inflammation, and many assays cannot measure that low, so a result reported as below 5 reads as in range. Results above 100 mg/L usually mean acute bacterial infection or active inflammatory disease. CRP rises within hours of infection or injury and falls over days, so repeat it once the person is well before reading anything into a mild rise.

Sources

  • C-reactive protein (CRP) — University Hospitals Birmingham NHS Foundation Trust, Pathology, 2026 · Laboratory / reference-interval sourceAdult reference range 0 to 5 mg/L on the Abbott assay. Up to 5 mg/L excludes many acute inflammatory diseases but not all inflammation, and above 100 mg/L suggests acute bacterial infection or active inflammation. Updated August 2026.
  • CRP (C-reactive protein) — Gloucestershire Hospitals NHS Foundation Trust, Pathology, 2026 · Laboratory / reference-interval sourceAdult reference range below 5 mg/L. Reviewed January 2026. A second NHS laboratory on the same edge.
  • C-Reactive Protein (CRP), Quantitative (test 006627) — Labcorp test directory, 2026 · Laboratory / reference-interval sourceAdult (over 17) interval 0 to 10 mg/L for both sexes. The page points to the separate high-sensitivity assay for cardiac risk. This is the 10 mg/L edge US reports print.
  • ABIM Laboratory Test Reference Ranges, January 2026 — American Board of Internal Medicine, 2026 · Laboratory / reference-interval sourceUS reference table: standard C-reactive protein 0.8 mg/dL or less (8 mg/L), listed separately from high-sensitivity CRP, which carries the cardiovascular risk categories (below 1, 1 to 3, above 3 mg/L).

Last reviewed: November 9, 2026 · CRP on its own page

hsCRP (High-Sensitivity C-Reactive Protein)Established clinical thresholdmg/L · mg/dL

A sensitive marker of inflammation throughout the body.

UnitOptimalSufficientOut of range
mg/L0 – 0.990 – 3below 0 or above 3
mg/dL0 – 0.0990 – 0.3below 0 or above 0.3

Interpretation: The bands follow the American Heart Association and CDC cardiovascular risk categories: below 1 mg/L is low risk, 1 to 3 is average risk, above 3 is high risk. US cardiology guidance also treats 2 mg/L or more as a risk-enhancing factor in primary prevention, so a result in the upper part of the acceptable band is not neutral. A single raised hsCRP can reflect any recent infection or injury. Cardiovascular risk stratification requires a repeat measurement when the person is well.

Sources

  • C-reactive protein — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceCiting the American Heart Association: low cardiovascular risk when hs-CRP is lower than 1.0 mg/L, average risk from 1.0 to 3.0 mg/L, high risk above 3.0 mg/L. Matches Sera's optimal and sufficient upper edges. Reviewed 28 January 2025.
  • C-Reactive Protein (CRP), High Sensitivity (test 120766) — Labcorp test directory, 2026 · Laboratory / reference-interval sourceReports hs-CRP against three risk categories: low risk below 1.00 mg/L, average risk 1.00 to 3.00, high risk above 3.00. Current directory entry, opened October 2026; it attributes the categories to the 2003 AHA/CDC statement.
  • Prioritizing Health | hsCRP: A Promising Risk Assessment Tool — American College of Cardiology, Cardiology Magazine, 2025 · Professional societyStates that an hsCRP of 2 mg/L or more counts as a risk-enhancing factor in primary prevention under current guidelines. This threshold falls inside Sera's sufficient band and supports the note, not a band edge.

Last reviewed: November 9, 2026 · hs-CRP on its own page

hsCRP / Albumin RatioNo universal rangeAuto-calculatedUnbandedratio · unbanded

High-sensitivity CRP in mg/L divided by albumin in g/L. Built on the hs-CRP assay specifically, not a standard CRP.

Auto-calculated

hsCRP (mg/L) / Albumin (g/L)

Calculated when hsCRP (High-Sensitivity C-Reactive Protein) and Albumin are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

No published threshold exists, and it has not been shown to add to CRP read on its own. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No reference interval or target exists for this ratio in healthy adults, so it is shown without bands and is best read as a trend within one person. In the UK Biobank (411,506 adults) the ratio predicted death and cardiovascular events no better than CRP alone. Reads inflammation against synthetic and nutritional reserve at once. The two inputs move in opposite directions during an acute-phase response, so the ratio amplifies a shift that either marker alone would understate — which is also why it exaggerates in anyone with a low albumin for unrelated reasons. The numerator is hs-CRP, not a standard CRP: the ordinary assay bottoms out around 3 to 5 mg/L, well above the range this ratio discriminates in, so the two are not substitutes here.

Sources

Last reviewed: November 9, 2026

FibrinogenPublished reference intervalmg/dL · g/L

The clotting protein the liver makes, which doubles as one of the acute-phase reactants.

UnitOptimalSufficientOut of range
mg/dL200 – 300150 – 400below 150 or above 400
g/L2 – 31.5 – 4below 1.5 or above 4

Interpretation: The acceptable band of 150 to 400 mg/dL (1.5 to 4.0 g/L) is a laboratory reference range. Laboratories differ: several start at 200 mg/dL (2.0 g/L), and Labcorp's adult range runs to 464, so read the result against the reporting laboratory's own range. The optimal band of 200 to 300 mg/dL (2 to 3 g/L) is a functional target, and the evidence does not sit neatly inside it: in an Italian cohort of 17,689 adults the lowest-risk group sat at about 3.0 to 3.2 g/L, and women below 2.6 g/L had higher mortality. A clotting factor and an acute-phase reactant at once, so the same raised value means different things depending on why it was ordered. Higher in pregnancy, on the combined pill, in smokers and with age; low in advanced liver disease and in consumptive coagulopathy. Read beside hsCRP.

Sources

  • Fibrinogen – Clauss — Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle Laboratories test directory, 2026 · Laboratory / reference-interval sourceAdult reference range for Clauss fibrinogen of 1.5 to 4.0 g/L, the same as Sera's sufficient band. Page last updated 28 January 2026.
  • Fibrinogen blood test — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal range of 200 to 400 mg/dL (2.0 to 4.0 g/L). Matches Sera's sufficient upper edge; its lower edge is 200, not Sera's 150. Reviewed 3 February 2025.
  • Clauss Fibrinogen — North Bristol NHS Trust, Severn Pathology, 2023 · Laboratory / reference-interval sourceReference range of 2.0 to 4.0 g/L, in force from 24 April 2023. Matches the upper edge and shows that UK laboratories differ on the lower one (1.5 or 2.0).
  • Fibrinogen Activity (test 001610) — Labcorp test directory, 2026 · Laboratory / reference-interval sourceReference interval for people over 16 of 209 to 464 mg/dL, from Labcorp's own study. Wider at the top than Sera's 400: a result of 401 to 464 is in range at Labcorp. Current directory entry, opened October 2026.
  • Plasma fibrinogen levels and all-cause and cause-specific mortality in an Italian adult population: results from the Moli-sani study — Parisi R, Costanzo S, de Laat-Kremers R, Di Castelnuovo A, et al. — Bleeding, Thrombosis and Vascular Biology, 2023 · Peer-reviewed publicationIn 17,689 Italian adults followed 11.2 years, women in the lowest fifth (1.12 to 2.64 g/L) and the highest fifth (3.62 g/L or more) had higher all-cause mortality than the middle fifth (2.97 to 3.23 g/L); in men risk rose linearly. Does not support an optimal band of 2 to 3 g/L. Abstract read through the DOAJ record, not Europe PMC.

Last reviewed: November 9, 2026 · Fibrinogen on its own page

D-dimerEstablished clinical thresholdAssay-dependentng/mL FEU · μg/L FEU · mg/L FEU

A fragment released when cross-linked fibrin is broken down, indicating that clot has formed and is being dissolved somewhere in the body.

UnitOptimalSufficientOut of range
ng/mL FEU0 – 500—below 0 or above 500
μg/L FEU0 – 500—below 0 or above 500
mg/L FEU0 – 0.5—below 0 or above 0.5

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Only ever a rule-out. Below 500 ng/mL FEU (0.5 mg/L FEU) is the standard cut-off for excluding venous thromboembolism in someone at low clinical probability. From age 50 laboratories and NICE allow an age-adjusted cut-off instead: age times 10 in ng/mL FEU, so 600 at 60 and 800 at 80. Sera does not apply that adjustment, so a result just above 500 in an older client may still be negative by their laboratory's rule. Infection, inflammation, surgery, pregnancy, malignancy and age all raise it, so a high value on its own means little, while a low value genuinely lowers the probability of thrombosis. Units are the real hazard: fibrinogen-equivalent units are twice D-dimer units for the same sample, so a DDU result entered against these bands reads as half of what it is. Cut-offs are also specific to the assay; the reporting laboratory's own cut-off takes precedence.

Sources

  • D-Dimer (test 115188): age-adjusted cutoff — Labcorp test directory, 2026 · Laboratory / reference-interval sourceGives the age-adjusted cut-off for people over 50 as age divided by 100 in mg/L FEU, citing the American College of Physicians. This is the only evidenced threshold between 500 and 1000 ng/mL FEU, and it depends on age.
  • Venous thromboembolic diseases: diagnosis, management and thrombophilia testing (NG158) — National Institute for Health and Care Excellence, 2023 · Clinical guidelineRecommendation 1.1.14: consider an age-adjusted D-dimer threshold for people aged over 50. Published March 2020, last updated August 2023. It gives no number, so it supports the note and not a band edge.

Last reviewed: November 9, 2026 · D-dimer on its own page

ESR (Erythrocyte Sedimentation Rate)Published reference intervalSex-specificmm/hr

A general marker of inflammation in the body.

UnitApplies toOptimalSufficientOut of range
mm/hrFemale0 – 100 – 20below 0 or above 20
mm/hrMale0 – 50 – 20below 0 or above 20

Interpretation: The acceptable band ends at 20 mm/hr, the published upper limit for women under 50 and for men over 50. ESR rises with age and is higher in women: the limit usually quoted is 15 for men under 50 and 30 for women over 50, and Sera does not adjust for age, so a man under 50 between 15 and 20 is above his laboratory's range and a woman over 50 between 20 and 30 is within hers. The narrower optimal bands, ending at 10 for women and 5 for men, are functional targets with no published evidence behind them. Laboratories using automated methods print their own limits, which take precedence.

Sources

  • ESR — MedlinePlus Medical Encyclopedia, US National Library of Medicine, 2025 · Government / public-health guidanceNormal Westergren results: men under 50 less than 15 mm/hr, men over 50 less than 20, women under 50 less than 20, women over 50 less than 30. Sera's edge of 20 matches women under 50 and men over 50. Reviewed 1 July 2025.
  • Sedimentation Rate, Modified Westergren (test 005215) — Labcorp test directory, 2026 · Laboratory / reference-interval sourceMen 0 to 15 mm/hour up to age 50 and 0 to 30 after; women 0 to 32 up to 50 and 0 to 40 after. Agrees with 15 for younger men; wider than Sera's 20 for women and for older men. Current directory entry, opened October 2026.
  • Erythrocyte Sedimentation Rate Reference Intervals Determined via VES-MATIC 5 and CUBE 30 Touch with Respect to the Westergren Method — Lorubbio M, Diamanti D, Pieroni C, et al. — Diagnostics (Basel), 2025 · Peer-reviewed publicationIn 989 presumably healthy Italian adults, Westergren reference intervals were 1 to 22 mm/h for women of any adult age, 1 to 14 for men aged 18 to 69 and 1 to 22 for men of 70 or more. Close to Sera's 20 for women; lower for most men.

Last reviewed: November 9, 2026 · ESR on its own page

SII (Systemic Immune-Inflammation Index)Exploratory indexAuto-calculatedindex

Platelets multiplied by neutrophils, divided by lymphocytes, all in ×10⁹/L.

Auto-calculated

Platelets × Neutrophils / Lymphocytes (all ×10⁹/L)

Calculated when Platelets (Thrombocytes) and Neutrophils # and Lymphocytes # are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
index0 – 5000 – 1,168below 0 or above 1,168

Interpretation: The acceptable band ends at 1168, the upper limit of the 95% reference interval in the Rotterdam Study (8,711 Dutch adults aged 45 and over, mean 459). That is one cohort of older adults and is not an outcome threshold; SII rises with age and runs higher in women. The optimal band ending at 500 is a functional target with no published threshold behind it. Extends the neutrophil-to-lymphocyte ratio by adding platelets, on the reasoning that platelets participate in inflammation. The evidence is prognostic and observational, and thresholds differ between the populations they were derived in — read it as a trend within one person rather than against a population cut-off.

Sources

Last reviewed: November 9, 2026

Fatty Acids · 63 markers

The fat composition of red blood cell membranes, and the omega balance it reflects. RBC markers are a percentage of the total fatty acids identified in the membrane and reflect long-term status over weeks to months; plasma/serum % markers are a share of the fatty acids in plasma and reflect the last days to couple of weeks; plasma/serum concentration markers are amounts per litre reflecting the last few days of intake. They are not directly comparable.

Omega-316 markers

Omega-3 IndexFunctional / longevity target%

The share of EPA and DHA, two omega-3 fats, in your red blood cell membranes.

UnitOptimalSufficientOut of range
%8 – 124 – 8below 4 or above 12

Interpretation: The best-evidenced marker in this area. Harris and von Schacky proposed red cell EPA plus DHA as a risk marker, with 8 to 12% the low-risk zone and below 4% high risk. A 2017 analysis of 10 cohorts estimated about 30% lower risk of fatal coronary disease at 8% than at 4%, and Canada's national health survey uses the same two cut-points. Average levels in the United States, Canada, Germany and Italy are 4.5 to 5.8%, so a Sufficient result is the usual finding. Observational, though: no trial has shown that raising the Index to a target changes outcome, which is why this is a functional target rather than an established threshold. The 12% upper edge is the top of the proposed target range, not a level shown to cause harm. Not interchangeable between laboratories: small differences in analytical method give large differences in the Index, and the published cut-offs belong to the original standardised method, so a result from another method should not be read against them as if it were the same test.

Sources

Last reviewed: November 9, 2026 · Omega-3 Index on its own page

EPA (C20:5 n-3, RBC)Functional / longevity targetAssay-dependent%

Eicosapentaenoic acid. A long-chain omega-3 fatty acid from oily fish and algae, measured as a share of the fatty acids in red blood cell membranes.

UnitOptimalSufficientOut of range
%1 – 40.5 – 5below 0.5 or above 5

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: EPA alone is less well validated than EPA plus DHA: the outcome data sit with the Omega-3 Index, not with either fatty acid on its own, so these bands are functional targets rather than thresholds. In the Framingham cohort the lowest fifth of red cell EPA was below 0.44% and the highest above 0.92%, with lower mortality from the middle fifths upward; the 0.5 and 1 edges sit close to those figures. Average levels in North American and European cohorts are 0.4 to 1.1%, and about 2% in Japan and Korea. The upper edges have no published threshold behind them. The fastest-moving marker on the panel: it answers to a change in intake within weeks, where DHA takes months.

Sources

Last reviewed: November 9, 2026 · EPA (omega-3) on its own page

DHA (C22:6 n-3, RBC)Functional / longevity targetAssay-dependent%

Docosahexaenoic acid. A long-chain omega-3 fatty acid concentrated in brain and retinal tissue, measured as a share of red blood cell membrane fatty acids.

UnitOptimalSufficientOut of range
%3 – 82 – 10below 2 or above 10

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: DHA-specific outcome thresholds are less established than for the Omega-3 Index; the bands reflect functional targets and population distributions rather than a validated cut-off. Slower to shift than EPA, so a low value reflects a longer-standing pattern rather than the last few weeks. No reference interval or guideline threshold exists for red cell DHA as a percentage. In the Framingham cohort the highest fifth, above about 6%, had fewer cardiovascular events and lower mortality than the lowest fifth, below about 3.7%; the optimal band here starts at 3%, inside that lowest fifth.

Sources

Last reviewed: November 9, 2026 · DHA (omega-3) on its own page

DPA (C22:5 n-3, RBC)No universal rangeUnbandedAssay-dependent% · unbanded

Docosapentaenoic acid. An omega-3 fatty acid that sits between EPA and DHA in the elongation pathway.

No universal Sera range published.

No published interval or threshold exists, and typical red cell values sat above the band it had. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No band is shown. Red cell DPA averages 1.6 to 2.7% of fatty acids in the large North American and European cohorts measured by one method, and no adult reference interval or outcome threshold has been published; the figure also depends on the laboratory's method. Limited outcome data: one review found red cell DPA did not predict mortality or cardiovascular events, while a pooled analysis of 17 cohorts found higher circulating DPA went with lower mortality. An interconversion reservoir between EPA and DHA, which is why it moves less with intake than either. Absent from the shorter panels.

Sources

Last reviewed: November 9, 2026

ALA (C18:3 n-3, RBC)Exploratory indexOne-sidedAssay-dependent%

Alpha-linolenic acid. The plant-derived omega-3 found in flax, chia and walnuts, and the precursor the body can elongate into EPA.

UnitOptimalSufficientOut of range
%0.1 – 0.50.05 – 1above 1

Bounded on the high side only — a low result is not treated as out of range. No source gives a lower limit and pooled cohort data show no outcome tied to a low value.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Reflects plant omega-3 intake more than tissue omega-3 status, and conversion to EPA runs at a few percent with DHA lower still. Red cell ALA averages 0.1 to 0.4% in published cohorts, which is what the optimal band reflects. No outcome-linked threshold exists: a pooled analysis of 17 cohorts found no association between circulating ALA and mortality, so this is an exploratory index and a low result is not flagged. The upper edge has no published threshold behind it. A normal ALA beside a low Omega-3 Index is the usual picture in someone eating flax or walnuts but no fish.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell ALA measured by one method in 17 cohorts: all below 0.4%, from 0.10% (Italy, two United States laboratory datasets) to 0.29% in Canada and 0.39% in Korea. Consistent with Sera's optimal band of 0.1 to 0.5%; typical level only, no interval.
  • Blood n-3 fatty acid levels and total and cause-specific mortality from 17 prospective studies — Harris WS, Tintle NL, Imamura F, et al. (Fatty Acids and Outcomes Research Consortium) — Nature Communications, 2021 · Peer-reviewed publicationPooled analysis of 17 cohorts, 42,466 people: the long-chain omega-3s were associated with 15 to 18% lower mortality, but alpha-linolenic acid showed no association. No outcome supports flagging a low or a high ALA.

Last reviewed: November 9, 2026

EPA (C20:5 n-3, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

Eicosapentaenoic acid, a long-chain omega-3 fatty acid from oily fish and algae, measured as a share of the fatty acids in plasma.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Plasma EPA is the share of eicosapentaenoic acid in the fatty acids of plasma. Plasma fatty acids turn over in days to a couple of weeks, so a plasma result moves with recent meals and supplements and is a short-term reading, unlike the red cell value, which reflects the last two to three months. No guideline or reference laboratory has set a plasma percentage range, and the US National Institutes of Health states that experts have not established one. Sera records the value without a band. Laboratories measure different fractions (total plasma lipids, plasma phospholipids, or whole blood), and the same blood gives different percentages in each, so compare results only within one laboratory and method. Read it beside the red cell EPA and the Omega-3 Index where both were measured.

Sources

  • Omega-3 Fatty Acids: Health Professional Fact Sheet (updated August 22, 2025) — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that experts have not established normal ranges for omega-3s measured in plasma or serum phospholipids as a percentage of total fatty acids, and gives a mean of about 3 to 4% EPA plus DHA in US adults not taking supplements. It also says plasma and serum values vary with the most recent meal and do not reflect long-term intake.
  • OmegaCheck (test mnemonic OMEGAC) — Cleveland Clinic Laboratories (performed by Cleveland HeartLab, Inc.), 2026 · Laboratory / reference-interval sourceCleveland HeartLab's OmegaCheck interval for EPA: 0.2 to 2.3% by weight. The test is collected as EDTA whole blood and analysed by LC-MS/MS. One laboratory's interval for a whole blood method.
  • OmegaCheck® (test code 92701) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceQuest's own directory entry for OmegaCheck: the preferred specimen is EDTA whole blood, not centrifuged, analysed by LC/MS/MS. The reference range field reads 'See Laboratory Report'. This is why the OmegaCheck intervals below describe a whole blood test, not a plasma one.
  • PFAPE - Overview: Fatty Acid Profile, Essential, Plasma — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceMayo's plasma essential fatty acid profile (GC-MS, stable isotope dilution) reports each acid as a concentration in nmol/mL, not as a percentage. Cited to show that Mayo's plasma interval cannot be applied to a percentage result.

Last reviewed: November 9, 2026

DHA (C22:6 n-3, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

Docosahexaenoic acid, the long-chain omega-3 concentrated in brain and retina, measured as a share of the fatty acids in plasma.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Plasma DHA is the share of docosahexaenoic acid in the fatty acids of plasma. Plasma fatty acids turn over in days to a couple of weeks, so a plasma result moves with recent meals and supplements and is a short-term reading, unlike the red cell value, which reflects the last two to three months. No guideline or reference laboratory has set a plasma percentage range, and the US National Institutes of Health states that experts have not established one. In large European cohorts a higher circulating DHA share went with fewer coronary events, but no cut-off was defined. Sera records the value without a band. Laboratories measure different fractions (total plasma lipids, plasma phospholipids, or whole blood), and the same blood gives different percentages in each, so compare results only within one laboratory and method. Read it beside the red cell DHA and the Omega-3 Index where both were measured.

Sources

  • Omega-3 Fatty Acids: Health Professional Fact Sheet (updated August 22, 2025) — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that experts have not established normal ranges for omega-3s measured in plasma or serum phospholipids as a percentage of total fatty acids, and gives a mean of about 3 to 4% EPA plus DHA in US adults not taking supplements. It also says plasma and serum values vary with the most recent meal and do not reflect long-term intake.
  • OmegaCheck (test mnemonic OMEGAC) — Cleveland Clinic Laboratories (performed by Cleveland HeartLab, Inc.), 2026 · Laboratory / reference-interval sourceCleveland HeartLab's OmegaCheck interval for EPA: 0.2 to 2.3% by weight. The test is collected as EDTA whole blood and analysed by LC-MS/MS. One laboratory's interval for a whole blood method.
  • OmegaCheck® (test code 92701) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceQuest's own directory entry for OmegaCheck: the preferred specimen is EDTA whole blood, not centrifuged, analysed by LC/MS/MS. The reference range field reads 'See Laboratory Report'. This is why the OmegaCheck intervals below describe a whole blood test, not a plasma one.
  • Association of circulating fatty acids with cardiovascular disease risk: analysis of individual-level data in three large prospective cohorts and updated meta-analysis — Shi F, Chowdhury R, Sofianopoulou E, et al. — Eur J Prev Cardiol, 2025 · Peer-reviewed publicationIn 172,891 adults from EPIC-CVD, UK Biobank and INTERVAL, circulating fatty acids were measured as a percentage of total fatty acids. Per 1 SD higher, total omega-3 and DHA were each associated with 9% lower incident coronary heart disease (HR 0.91). Direction only, no threshold.
  • PFAPE - Overview: Fatty Acid Profile, Essential, Plasma — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceMayo's plasma essential fatty acid profile (GC-MS, stable isotope dilution) reports each acid as a concentration in nmol/mL, not as a percentage. Cited to show that Mayo's plasma interval cannot be applied to a percentage result.

Last reviewed: November 9, 2026

DPA (C22:5 n-3, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

Docosapentaenoic acid, the omega-3 that sits between EPA and DHA in the elongation pathway, measured as a share of the fatty acids in plasma.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Plasma DPA is the share of omega-3 docosapentaenoic acid in the fatty acids of plasma. It sits between EPA and DHA in the elongation pathway and moves less with intake than either. Plasma fatty acids turn over in days to a couple of weeks, so a plasma result moves with recent meals and supplements and is a short-term reading, unlike the red cell value, which reflects the last two to three months. No guideline or reference laboratory has set a plasma percentage range, so Sera records the value without a band. Laboratories measure different fractions (total plasma lipids, plasma phospholipids, or whole blood), and the same blood gives different percentages in each, so compare results only within one laboratory and method. Some panels also report an omega-6 DPA, which is a different fatty acid.

Sources

  • Omega-3 Fatty Acids: Health Professional Fact Sheet (updated August 22, 2025) — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that experts have not established normal ranges for omega-3s measured in plasma or serum phospholipids as a percentage of total fatty acids, and gives a mean of about 3 to 4% EPA plus DHA in US adults not taking supplements. It also says plasma and serum values vary with the most recent meal and do not reflect long-term intake.
  • OmegaCheck (test mnemonic OMEGAC) — Cleveland Clinic Laboratories (performed by Cleveland HeartLab, Inc.), 2026 · Laboratory / reference-interval sourceCleveland HeartLab's OmegaCheck interval for EPA: 0.2 to 2.3% by weight. The test is collected as EDTA whole blood and analysed by LC-MS/MS. One laboratory's interval for a whole blood method.
  • OmegaCheck® (test code 92701) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceQuest's own directory entry for OmegaCheck: the preferred specimen is EDTA whole blood, not centrifuged, analysed by LC/MS/MS. The reference range field reads 'See Laboratory Report'. This is why the OmegaCheck intervals below describe a whole blood test, not a plasma one.
  • PFAPE - Overview: Fatty Acid Profile, Essential, Plasma — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceMayo's plasma essential fatty acid profile (GC-MS, stable isotope dilution) reports each acid as a concentration in nmol/mL, not as a percentage. Cited to show that Mayo's plasma interval cannot be applied to a percentage result.

Last reviewed: November 9, 2026

Omega-3 Total (EPA+DPA+DHA, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

The combined share of the three long-chain omega-3s, EPA, DPA and DHA, in the fatty acids of plasma. Narrower than an omega-3 total that also counts ALA, and not the same as the Omega-3 Index, which is EPA and DHA in red cells.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Total plasma omega-3 here is EPA plus DPA plus DHA as a share of the fatty acids in plasma. Plasma fatty acids turn over in days to a couple of weeks, so a plasma result moves with recent meals and supplements and is a short-term reading, unlike the red cell value, which reflects the last two to three months. No guideline or reference laboratory has set a plasma range, and the US National Institutes of Health states that experts have not established one, so Sera records the value without a band. Sera also holds Quest's OmegaCheck here: the report heads the panel as plasma and the result is a share of plasma phospholipid fatty acids, though the sample is drawn as whole blood. Its risk categories (5.5% by weight or more low, 3.8 to 5.4 moderate, 3.7 or less high) are the quartiles of that laboratory's own population. Laboratories measure different fractions (total plasma lipids, plasma phospholipids, or whole blood), and the same blood gives different percentages in each, so compare results only within one laboratory and method. Read it beside the Omega-3 Index where both were measured.

Sources

  • OmegaCheck: Test Guide (content reviewed 9/2025) — Quest Diagnostics, 2025 · Laboratory / reference-interval sourceQuest's test guide gives the OmegaCheck interpretation table: 5.5% by weight or more low cardiovascular risk, 3.8 to 5.4 moderate, 3.7 or less high, and says the test measures omega-3s in whole blood, calculated as EPA plus DPA plus DHA over total phospholipid fatty acids.
  • OmegaCheck sample laboratory report (OMEGC), performed by Cleveland HeartLab, Inc. — Warde Medical Laboratory (referral report of the Quest Diagnostics / Cleveland HeartLab test), 2024 · Laboratory / reference-interval sourceThe report comment states that the three OmegaCheck risk categories were set at the 25th and 75th percentiles of Cleveland HeartLab's own reference population: 5.5% by weight or more low relative risk, 3.8 to 5.4 moderate, 3.7 or less high. They are population quartiles, not outcome-derived cut-offs.
  • OmegaCheck (test mnemonic OMEGAC) — Cleveland Clinic Laboratories (performed by Cleveland HeartLab, Inc.), 2026 · Laboratory / reference-interval sourceCleveland HeartLab's OmegaCheck interval for EPA: 0.2 to 2.3% by weight. The test is collected as EDTA whole blood and analysed by LC-MS/MS. One laboratory's interval for a whole blood method.
  • OmegaCheck® (test code 92701) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceQuest's own directory entry for OmegaCheck: the preferred specimen is EDTA whole blood, not centrifuged, analysed by LC/MS/MS. The reference range field reads 'See Laboratory Report'. This is why the OmegaCheck intervals below describe a whole blood test, not a plasma one.
  • Omega-3 Fatty Acids: Health Professional Fact Sheet (updated August 22, 2025) — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that experts have not established normal ranges for omega-3s measured in plasma or serum phospholipids as a percentage of total fatty acids, and gives a mean of about 3 to 4% EPA plus DHA in US adults not taking supplements. It also says plasma and serum values vary with the most recent meal and do not reflect long-term intake.
  • Association of circulating fatty acids with cardiovascular disease risk: analysis of individual-level data in three large prospective cohorts and updated meta-analysis — Shi F, Chowdhury R, Sofianopoulou E, et al. — Eur J Prev Cardiol, 2025 · Peer-reviewed publicationIn 172,891 adults from EPIC-CVD, UK Biobank and INTERVAL, circulating fatty acids were measured as a percentage of total fatty acids. Per 1 SD higher, total omega-3 and DHA were each associated with 9% lower incident coronary heart disease (HR 0.91). Direction only, no threshold.

Last reviewed: November 9, 2026

Omega-3 Index (EPA+DHA, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

EPA and DHA combined, as a share of the fatty acids in plasma. The same sum as the Omega-3 Index, measured in plasma instead of red cells.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The share of EPA plus DHA in the fatty acids of plasma. It is the same sum as the Omega-3 Index, but the Index and its 8% and 4% cut-offs are defined in red cell membranes, and the same blood gives a different percentage in plasma. Plasma fatty acids turn over in days to a couple of weeks, so the result moves with recent meals and supplements and is a short-term reading. No guideline or reference laboratory has set a plasma range, and the US National Institutes of Health states that experts have not established one, giving a mean of about 3 to 4% for EPA plus DHA in US adults who take no supplements. Sera records the value without a band. Read it beside the red cell Omega-3 Index where both were measured.

Sources

  • Omega-3 Fatty Acids: Health Professional Fact Sheet (updated August 22, 2025) — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that experts have not established normal ranges for omega-3s measured in plasma or serum phospholipids as a percentage of total fatty acids, and gives a mean of about 3 to 4% EPA plus DHA in US adults not taking supplements. It also says plasma and serum values vary with the most recent meal and do not reflect long-term intake.

Last reviewed: November 9, 2026

ALA (C18:3 n-3, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

Alpha-linolenic acid, the plant omega-3 from flax, chia and walnuts, measured as a share of the fatty acids in plasma.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Plasma ALA is the share of alpha-linolenic acid, the plant omega-3, in the fatty acids of plasma. Plasma fatty acids turn over in days to a couple of weeks, so a plasma result moves with recent meals and supplements and is a short-term reading, unlike the red cell value, which reflects the last two to three months. No guideline or reference laboratory has set a plasma percentage range for ALA, and the US National Institutes of Health states that experts have not established normal ranges for omega-3s in plasma, so Sera records the value without a band. Laboratories measure different fractions (total plasma lipids, plasma phospholipids, or whole blood), and the same blood gives different percentages in each, so compare results only within one laboratory and method.

Sources

  • Omega-3 Fatty Acids: Health Professional Fact Sheet (updated August 22, 2025) — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that experts have not established normal ranges for omega-3s measured in plasma or serum phospholipids as a percentage of total fatty acids, and gives a mean of about 3 to 4% EPA plus DHA in US adults not taking supplements. It also says plasma and serum values vary with the most recent meal and do not reflect long-term intake.

Last reviewed: November 9, 2026

EPA (C20:5 n-3, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Eicosapentaenoic acid measured as a concentration in serum, rather than as a share of red cell membrane fat.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Reflects the last few days of intake rather than status: a fish meal or a missed capsule moves it. Useful for confirming absorption, not for judging long-term omega-3 status — the Omega-3 Index answers that, and the two are not interchangeable. No guideline publishes an adult range. Mayo Clinic Laboratories gives an adult interval of 14 to 100 nmol/mL for total serum by GC-MS; it applies only to a total-serum concentration in that unit, not to a percentage of total fatty acids or a phospholipid result.

Sources

  • FAPEP - Fatty Acid Profile, Essential, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 years and over) reference interval for EPA (C20:5 n-3) in total serum by GC-MS: 14 to 100 nmol/mL. The page says concentrations below the reference range are consistent with fatty acid deficiency. Sera has no band; this is one laboratory's interval for total serum lipids only, and the page does not say how it was derived.

Last reviewed: November 9, 2026

DHA (C22:6 n-3, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Docosahexaenoic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Steadier than serum EPA but still driven by recent intake. Read a low value as a prompt to check the Omega-3 Index rather than as evidence of tissue depletion. No guideline publishes an adult range. Mayo Clinic Laboratories gives an adult interval of 30 to 250 nmol/mL for total serum by GC-MS; it applies only to a total-serum concentration in that unit, not to a percentage of total fatty acids or a phospholipid result.

Sources

  • FAPEP - Fatty Acid Profile, Essential, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 years and over) reference interval for DHA (C22:6 n-3) in total serum by GC-MS: 30 to 250 nmol/mL. The page says concentrations below the reference range are consistent with fatty acid deficiency. Sera has no band; this is one laboratory's interval for total serum lipids only, and the page does not say how it was derived.

Last reviewed: November 9, 2026

ALA (C18:3 n-3, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Alpha-linolenic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The plant omega-3, and the fastest of them to reflect what was eaten: flax, chia or walnuts move it within days. Conversion onward to EPA and DHA is very limited (the NIH puts reported rates below 15%), so an adequate serum ALA says nothing about EPA and DHA status; read the Omega-3 Index for that. No band is shown because no guideline sets one: the NIH states that experts have not established normal ranges for omega-3s in serum, and serum values swing with the most recent meal. Mayo Clinic Laboratories reports 50 to 130 nmol/mL for adults in serum; that interval applies to that method only, so read the result against the range printed on the client's own report.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for alpha-linolenic acid: 50 to 130 nmol/mL. It is one laboratory's interval, cited to show a range exists for this method, not as a band Sera applies.
  • Omega-3 Fatty Acids - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that omega-3 status is measured in plasma or serum phospholipids as a percentage of total phospholipid fatty acids, that experts have not established normal ranges, and that ALA conversion to EPA and DHA is below 15%. Supports publishing no band.

Last reviewed: November 9, 2026

DPA (C22:5 n-3, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Docosapentaenoic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: An interconversion reservoir between EPA and DHA, convertible in either direction, so it moves less with intake than either neighbour. Reported only by the fuller gas-chromatography panels. No band is shown because no guideline sets one. Mayo Clinic Laboratories reports 20 to 210 nmol/mL for adults in serum, a tenfold span that applies to that method only. The same panels also report an omega-6 DPA (C22:5 n-6, 10 to 70 nmol/mL at Mayo), so check which isomer the line refers to before reading it.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for docosapentaenoic acid (C22:5 n-3): 20 to 210 nmol/mL. It is one laboratory's interval, cited to show a range exists for this method, not as a band Sera applies.
  • Omega-3 Fatty Acids - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that experts have not established normal ranges for omega-3 status in serum or plasma. Supports publishing no band.

Last reviewed: November 9, 2026

Total Omega-3 (Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

The sum of the omega-3 fatty acids measured on a serum panel.

No universal Sera range published.

A sum whose constituents vary by panel, over a concentration whose lipid fraction varies by laboratory. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Comparable only against itself. Which fatty acids a laboratory sums into the total differs between panels, so the same blood yields different totals at different labs. Not the Omega-3 Index, which is a percentage of red cell membrane fat. No band is shown because no guideline sets one: the NIH states that experts have not established normal ranges for omega-3s in serum. Mayo Clinic Laboratories reports 0.2 to 0.5 mmol/L for fasting adults, without listing which fatty acids its total includes.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for total omega-3: 0.2 to 0.5 mmol/L. The page does not list the fatty acids summed. One laboratory's interval, cited for context, not as a band Sera applies.
  • Omega-3 Fatty Acids - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates that omega-3 status is assessed as a percentage of phospholipid fatty acids, that experts have not established normal ranges, and that serum values vary with the most recent meal. Supports publishing no band for a serum total.

Last reviewed: November 9, 2026

Omega-614 markers

AA (C20:4 n-6, RBC)Published reference intervalAssay-dependent%

Arachidonic acid. A long-chain omega-6 fatty acid and the substrate for the inflammatory eicosanoids, measured as a share of red blood cell membrane fatty acids.

UnitOptimalSufficientOut of range
%10 – 158 – 20below 8 or above 20

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Bands reflect population distributions rather than an outcome-linked target. Functional interpretation depends on the AA:EPA balance rather than on AA alone — this is a necessary membrane component whose eicosanoids include resolving as well as inflammatory ones. A high AA with a low DGLA suggests an accelerated delta-5 desaturase step, which insulin drives. No published reference interval exists for red cell arachidonic acid as a percentage. Cohort means are 14 to 17% in Western populations, so with the optimal band ending at 15% the average Western result reads Sufficient; a pooled analysis of 30 cohorts found higher arachidonic acid was not associated with higher cardiovascular risk.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell arachidonic acid measured by one method: 14 to 17% in the United States, Canada, Germany, Spain and Italy (13.9 to 16.8%), about 12% in Japan, Korea and Alaska. Sera's optimal upper edge of 15% cuts through the middle of the Western means; the sufficient band of 8 to 20% contains all of them.
  • Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality — Marklund M, Wu JHY, Imamura F, et al. (CHARGE Fatty Acids and Outcomes Research Consortium) — Circulation, 2019 · Peer-reviewed publicationPooled analysis of 30 cohorts, 68,659 people: arachidonic acid levels were not associated with higher cardiovascular risk, and the highest fifth had a hazard ratio of 0.92 for total cardiovascular disease against the lowest. Mixed blood fractions; no threshold. No outcome basis for marking a higher AA down.

Last reviewed: November 9, 2026 · Arachidonic acid on its own page

LA (C18:2 n-6, RBC)Published reference intervalAssay-dependent%

Linoleic acid. The principal dietary omega-6, abundant in seed oils, and usually the largest polyunsaturated fraction in the membrane.

UnitOptimalSufficientOut of range
%10 – 208 – 25below 8 or above 25

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Bands reflect population averages, not a published reference interval: red cell linoleic acid averages 11 to 13% in North American, European and East Asian cohorts. The outcome evidence points one way: pooled analyses of prospective cohorts associate higher linoleic acid with lower cardiovascular risk and lower mortality, and none shows harm from a high level. The functional reading treats a high level as a marker of processed food intake; that reading has no outcome data behind it. None of the band edges has a published threshold. Read it as a dietary-pattern marker, not a verdict.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell linoleic acid measured by one method in 17 cohorts: 11 to 13% across countries (11.1 to 13.8%), with 17.5% in the Alaskan cohort. All inside Sera's optimal band of 10 to 20%; typical level only, no interval.
  • Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality — Marklund M, Wu JHY, Imamura F, et al. (CHARGE Fatty Acids and Outcomes Research Consortium) — Circulation, 2019 · Peer-reviewed publicationPooled analysis of 30 cohorts, 68,659 people: higher linoleic acid was associated with lower risk of total cardiovascular disease (hazard ratio 0.93), cardiovascular death (0.78) and ischaemic stroke (0.88) across the interquintile range. Mixed blood fractions; no threshold. No outcome basis for flagging a high result.
  • Dietary intake and biomarkers of linoleic acid and mortality: systematic review and meta-analysis of prospective cohort studies — Li J, Guasch-Ferré M, Li Y, Hu FB — The American Journal of Clinical Nutrition, 2020 · Peer-reviewed publicationMeta-analysis of 44 prospective cohorts: each standard deviation higher linoleic acid in blood or adipose tissue was associated with 9% lower total mortality, 11% lower cardiovascular mortality and 9% lower cancer mortality. Direction only; no threshold.

Last reviewed: November 9, 2026 · Linoleic acid on its own page

DGLA (C20:3 n-6, RBC)Exploratory indexOne-sidedAssay-dependent%

Dihomo-gamma-linolenic acid. An omega-6 fatty acid that yields the series-1 prostaglandins, which oppose rather than drive inflammation.

UnitOptimalSufficientOut of range
%0.5 – 1.50.3 – 2above 2

Bounded on the high side only — a low result is not treated as out of range. No source gives a lower limit for red cell DGLA and no outcome is tied to a low value.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No published threshold exists for red cell DGLA; the bands are Sera's own and have no source. Average levels in European and North American cohorts measured by one method were 1.6% to 1.9%, so a result just above the optimal band is ordinary. DGLA is the anti-inflammatory branch of the omega-6 pathway, yielding the series-1 prostaglandins. The AA-to-DGLA ratio estimates delta-5 desaturase activity. In the German EPIC-Potsdam cohort, which measured plasma lipids and not red cells, higher DGLA went with more new type 2 diabetes and higher estimated delta-5 desaturase activity with less, so it is a high DGLA with a low AA-to-DGLA ratio that tends to accompany insulin resistance. Percentages depend on which fatty acids the panel counts, so compare only within one laboratory.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell levels measured by one laboratory method in 17 cohorts (Italy, Spain, Germany, Canada, United States, Japan, Korea; 167,347 people). Cohort means only: the paper gives no percentiles or reference interval. DGLA (C20:3n6) means: 1.29% to 1.93% across all cohorts, 1.60% to 1.87% in the ten US cohorts, 1.86% in Canada. Supports no edge; shows the optimal ceiling of 1.5% is below the usual Western mean.
  • Plasma Lipidomic n-6 Polyunsaturated Fatty Acids and Type 2 Diabetes Risk in the EPIC-Potsdam Prospective Cohort Study — Prada M, Eichelmann F, Wittenbecher C, et al. — Diabetes Care, 2023 · Peer-reviewed publicationGerman case-cohort (1,084 subcohort, 536 incident type 2 diabetes), plasma lipid classes, not red cells. Higher 20:3 (DGLA) in phosphatidylcholines went with more diabetes (HR 1.63); higher estimated delta-5 desaturase activity went with less. Gives a direction, not a threshold.
  • Using an erythrocyte fatty acid fingerprint to predict risk of all-cause mortality: the Framingham Offspring Cohort — McBurney MI, Tintle NL, Vasan RS, et al. — The American Journal of Clinical Nutrition, 2021 · Peer-reviewed publicationFramingham Offspring, 2,240 adults, 27 red cell fatty acids as percent of total. Only myristic, palmitoleic, behenic acid and the Omega-3 Index predicted all-cause death; DGLA did not. Supports the statement that DGLA has no outcome-linked threshold.

Last reviewed: November 9, 2026

GLA (C18:3 n-6, RBC)Exploratory indexOne-sidedAssay-dependent%

Gamma-linolenic acid. An omega-6 fatty acid formed from linoleic acid, and the active component of evening primrose and borage oil.

UnitOptimalSufficientOut of range
%0.1 – 0.50.05 – 1above 1

Bounded on the high side only — a low result is not treated as out of range. Cohort means sit at or below 0.1 percent and no source gives a lower limit.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No published threshold exists for red cell GLA; the bands are Sera's own and have no source. It is present only in traces: cohort means measured by one method across seven countries were about 0.1% to 0.17%, and some cohorts averaged below 0.1%, so a low reading is ordinary and is not flagged. Outcome data are limited; the case for GLA is mostly mechanistic and supplementation-driven. A clearly raised level usually reflects evening primrose or borage oil and not diet.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell levels measured by one laboratory method in 17 cohorts (Italy, Spain, Germany, Canada, United States, Japan, Korea; 167,347 people). Cohort means only: the paper gives no percentiles or reference interval. GLA (C18:3n6) means: 0.09% to 0.17% outside the US and from below 0.10% to 0.17% in the US cohorts. Supports no edge; shows the usual level is about 0.1%.

Last reviewed: November 9, 2026

AA (C20:4 n-6, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

Arachidonic acid, the long-chain omega-6 fatty acid behind most inflammatory eicosanoids, measured as a share of the fatty acids in plasma.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Plasma arachidonic acid is the share of this omega-6 fatty acid in the fatty acids of plasma. It is a normal and necessary membrane component, and its main use is as the numerator of the AA to EPA ratio. Plasma fatty acids turn over in days to a couple of weeks, so a plasma result moves with recent meals and supplements and is a short-term reading, unlike the red cell value, which reflects the last two to three months. No guideline or reference laboratory has set a plasma percentage range, so Sera records the value without a band. Laboratories measure different fractions (total plasma lipids, plasma phospholipids, or whole blood), and the same blood gives different percentages in each, so compare results only within one laboratory and method.

Sources

  • OmegaCheck (test mnemonic OMEGAC) — Cleveland Clinic Laboratories (performed by Cleveland HeartLab, Inc.), 2026 · Laboratory / reference-interval sourceCleveland HeartLab's OmegaCheck interval for EPA: 0.2 to 2.3% by weight. The test is collected as EDTA whole blood and analysed by LC-MS/MS. One laboratory's interval for a whole blood method.
  • OmegaCheck® (test code 92701) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceQuest's own directory entry for OmegaCheck: the preferred specimen is EDTA whole blood, not centrifuged, analysed by LC/MS/MS. The reference range field reads 'See Laboratory Report'. This is why the OmegaCheck intervals below describe a whole blood test, not a plasma one.
  • PFAPE - Overview: Fatty Acid Profile, Essential, Plasma — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceMayo's plasma essential fatty acid profile (GC-MS, stable isotope dilution) reports each acid as a concentration in nmol/mL, not as a percentage. Cited to show that Mayo's plasma interval cannot be applied to a percentage result.

Last reviewed: November 9, 2026

LA (C18:2 n-6, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

Linoleic acid, the principal dietary omega-6 from seed oils, nuts and grains, measured as a share of the fatty acids in plasma.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Plasma linoleic acid is the share of the main dietary omega-6 in the fatty acids of plasma, and usually the largest polyunsaturated fraction. Plasma fatty acids turn over in days to a couple of weeks, so a plasma result moves with recent meals and supplements and is a short-term reading, unlike the red cell value, which reflects the last two to three months. No guideline or reference laboratory has set a plasma percentage range, so Sera records the value without a band. In large European cohorts a higher circulating share went with fewer strokes, so a high result is dietary information, not a finding. Laboratories measure different fractions (total plasma lipids, plasma phospholipids, or whole blood), and the same blood gives different percentages in each, so compare results only within one laboratory and method.

Sources

  • OmegaCheck (test mnemonic OMEGAC) — Cleveland Clinic Laboratories (performed by Cleveland HeartLab, Inc.), 2026 · Laboratory / reference-interval sourceCleveland HeartLab's OmegaCheck interval for EPA: 0.2 to 2.3% by weight. The test is collected as EDTA whole blood and analysed by LC-MS/MS. One laboratory's interval for a whole blood method.
  • OmegaCheck® (test code 92701) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceQuest's own directory entry for OmegaCheck: the preferred specimen is EDTA whole blood, not centrifuged, analysed by LC/MS/MS. The reference range field reads 'See Laboratory Report'. This is why the OmegaCheck intervals below describe a whole blood test, not a plasma one.
  • Association of circulating fatty acids with cardiovascular disease risk: analysis of individual-level data in three large prospective cohorts and updated meta-analysis — Shi F, Chowdhury R, Sofianopoulou E, et al. — Eur J Prev Cardiol, 2025 · Peer-reviewed publicationIn the same three European cohorts, per 1 SD higher, linoleic acid as a percentage of total fatty acids was associated with 11% lower incident stroke (HR 0.89). Direction only, no threshold.
  • PFAPE - Overview: Fatty Acid Profile, Essential, Plasma — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceMayo's plasma essential fatty acid profile (GC-MS, stable isotope dilution) reports each acid as a concentration in nmol/mL, not as a percentage. Cited to show that Mayo's plasma interval cannot be applied to a percentage result.

Last reviewed: November 9, 2026

AA (C20:4 n-6, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Arachidonic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The omega-6 substrate for the inflammatory eicosanoids. The AA:EPA ratio printed beside it travels between laboratories better than the raw concentration does, so prefer the ratio when comparing across panels. No guideline publishes an adult range. Mayo Clinic Laboratories gives an adult interval of 520 to 1,490 nmol/mL for total serum by GC-MS; it applies only to a total-serum concentration in that unit, not to a percentage of total fatty acids or a phospholipid result.

Sources

  • FAPEP - Fatty Acid Profile, Essential, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 years and over) reference interval for arachidonic acid (C20:4 n-6) in total serum by GC-MS: 520 to 1,490 nmol/mL. The page says concentrations below the reference range are consistent with fatty acid deficiency. Sera has no band; this is one laboratory's interval for total serum lipids only, and the page does not say how it was derived.

Last reviewed: November 9, 2026

LA (C18:2 n-6, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Linoleic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Almost always the largest single fatty acid on a serum panel, and the one most directly tied to seed-oil intake. Because it dwarfs the others, any total omega-6 figure reported alongside mostly restates it. No guideline publishes an adult range. Mayo Clinic Laboratories gives an adult interval of 2,270 to 3,850 nmol/mL for total serum by GC-MS; it applies only to a total-serum concentration in that unit, not to a percentage of total fatty acids or a phospholipid result. In UK cohorts measuring total plasma or serum, linoleic acid averaged 27 to 29% of total fatty acids, and a higher share went with lower stroke risk.

Sources

  • FAPEP - Fatty Acid Profile, Essential, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 years and over) reference interval for linoleic acid (C18:2 n-6) in total serum by GC-MS: 2,270 to 3,850 nmol/mL. The page says concentrations below the reference range are consistent with fatty acid deficiency. Sera has no band; this is one laboratory's interval for total serum lipids only, and the page does not say how it was derived.
  • Association of circulating fatty acids with cardiovascular disease risk: analysis of individual-level data in three large prospective cohorts and updated meta-analysis — Shi F, Chowdhury R, Sofianopoulou E, et al. — European Journal of Preventive Cardiology, 2024 · Peer-reviewed publicationMean linoleic acid as a percentage of total fatty acids: 29.2 (SD 3.4) in UK Biobank and 27.0 (SD 3.2) in INTERVAL (total plasma or serum), 22.6 (SD 3.2) in plasma phospholipid in EPIC-CVD. Higher linoleic acid was associated with lower stroke risk (HR 0.89 per SD). Population means, not a reference range.

Last reviewed: November 9, 2026

GLA (C18:3 n-6, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Gamma-linolenic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Present in traces unless someone is supplementing evening primrose or borage oil, so a clearly raised value usually means exactly that. No guideline publishes an adult range. Mayo Clinic Laboratories gives an adult interval of 16 to 150 nmol/mL for total serum by GC-MS; it applies only to a total-serum concentration in that unit, not to a percentage of total fatty acids or a phospholipid result.

Sources

  • FAPEP - Fatty Acid Profile, Essential, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 years and over) reference interval for gamma-linolenic acid (C18:3 n-6) in total serum by GC-MS: 16 to 150 nmol/mL. The page says concentrations below the reference range are consistent with fatty acid deficiency. Sera has no band; this is one laboratory's interval for total serum lipids only, and the page does not say how it was derived.

Last reviewed: November 9, 2026

DGLA (C20:3 n-6, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Dihomo-gamma-linolenic acid measured as a concentration in serum. Printed by some laboratories as eicosatrienoic acid (C20:3 w6).

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The anti-inflammatory branch of the omega-6 pathway. Watch the label: laboratories often print it as eicosatrienoic acid, which means DGLA with a w6 or n-6 suffix and Mead acid — an unrelated fatty acid — with w9. No guideline publishes an adult range. Mayo Clinic Laboratories gives an adult interval of 50 to 250 nmol/mL for total serum by GC-MS; it applies only to a total-serum concentration in that unit, not to a percentage of total fatty acids or a phospholipid result. The same panel lists Mead acid (C20:3w9) separately at 7 to 30 nmol/mL.

Sources

  • FAPEP - Fatty Acid Profile, Essential, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 years and over) reference interval for DGLA (homo-gamma-linolenic acid, C20:3 n-6) in total serum by GC-MS: 50 to 250 nmol/mL. The page says concentrations below the reference range are consistent with fatty acid deficiency. Sera has no band; this is one laboratory's interval for total serum lipids only, and the page does not say how it was derived.

Last reviewed: November 9, 2026

EDA (C20:2 n-6, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Eicosadienoic acid (C20:2 n-6), a minor omega-6 intermediate, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: A minor intermediate between linoleic acid and DGLA, reported only by the fuller gas-chromatography panels. Rarely acted on alone; held so a panel that reports it imports whole.

Sources

There is no band here to attribute to a source.

Last reviewed: November 9, 2026

Total Omega-6 (Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

The sum of the omega-6 fatty acids measured on a serum panel.

No universal Sera range published.

A sum whose constituents vary by panel, over a concentration whose lipid fraction varies by laboratory. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Dominated by linoleic acid, so this figure largely restates that one: at Mayo Clinic Laboratories the adult interval is 3.0 to 5.4 mmol/L for the total and 2.27 to 3.85 mmol/L for linoleic acid alone. As with the omega-3 total, the constituent list varies by panel, and Mayo does not print its own. No band is shown because no guideline sets one; read the result against the range printed on the client's own report.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for total omega-6: 3.0 to 5.4 mmol/L; linoleic acid alone is 2,270 to 3,850 nmol/mL on the same page. The page does not list the fatty acids summed. One laboratory's interval, cited for context.

Last reviewed: November 9, 2026

Adrenic Acid (C22:4 n-6, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Adrenic (docosatetraenoic) acid, the omega-6 fatty acid made by lengthening arachidonic acid by two carbons, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Adrenic (docosatetraenoic) acid is a 22-carbon omega-6 fatty acid. No cohort evidence from Europe or North America was found linking a serum concentration to an outcome, so a result has no established reading on its own. For scale, one US reference laboratory reports 10 to 80 nmol/mL in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for docosatetraenoic (adrenic) acid, C22:4w6: 10 to 80 nmol/mL. One laboratory's interval, cited to show the scale of a serum result, not a band Sera applies. The page gives no interpretation for this acid.

Last reviewed: November 9, 2026

Omega-6 DPA (C22:5 n-6, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Omega-6 docosapentaenoic acid, also called osbond acid: the end of the omega-6 pathway, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Omega-6 DPA (osbond acid) is a 22-carbon omega-6 fatty acid, reported separately from the omega-3 DPA. No cohort evidence from 2016 onward was found linking a serum concentration to an outcome. For scale, one US reference laboratory reports 10 to 70 nmol/mL in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for omega-6 docosapentaenoic acid, C22:5w6: 10 to 70 nmol/mL. One laboratory's interval, cited for scale only. The page gives no interpretation for this acid and lists it separately from omega-3 DPA (C22:5w3, 20 to 210 nmol/mL).

Last reviewed: November 9, 2026

Omega-7 and omega-53 markers

Myristoleic Acid (C14:1 n-5, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Myristoleic acid, a minor monounsaturated fatty acid made from myristic acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Myristoleic acid is a 14-carbon monounsaturated fatty acid present in serum in small amounts. No European or North American evidence was found linking its concentration to any outcome, so a result has no established reading. For scale, one US reference laboratory reports 3 to 64 nmol/mL in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

Last reviewed: November 9, 2026

Palmitoleic Acid (C16:1 n-7, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Palmitoleic acid, the monounsaturated fatty acid the body makes from palmitic acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Palmitoleic acid is a product of de novo lipogenesis, the pathway by which the body makes fat from carbohydrate, protein or alcohol, so read a high result alongside triglycerides. In a pooled analysis of 17 cohorts, people at the top of the range had about 40% more incident type 2 diabetes than those at the bottom. For scale, one US reference laboratory reports 110 to 1,130 nmol/mL in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

Last reviewed: November 9, 2026

cis-Vaccenic Acid (C18:1 n-7, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

cis-Vaccenic acid, the monounsaturated fatty acid made by lengthening palmitoleic acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: cis-Vaccenic acid is an 18-carbon omega-7 monounsaturated fatty acid. There is little evidence on what a serum concentration means: one small Czech study in men with hyperlipidaemia found higher plasma phospholipid levels went with lower insulin and HOMA-IR, and its authors note that other studies disagree. For scale, one US reference laboratory reports 280 to 740 nmol/mL in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

Last reviewed: November 9, 2026

Omega-94 markers

Oleic Acid (C18:1 n-9, RBC)Published reference intervalAssay-dependent%

The monounsaturated omega-9 fatty acid that dominates olive oil, and typically the single largest fatty acid in the membrane after palmitic acid.

UnitOptimalSufficientOut of range
%10 – 208 – 25below 8 or above 25

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No published reference interval or clinical threshold exists for red cell oleic acid in percent; the bands are Sera's own. They are consistent with cohort averages measured by one method across seven countries: 13.5% to 16.5% in most cohorts and 17.6% to 18.9% in Spanish and Italian ones. The outer edges of 8% and 25% have no source. Not essential — the body synthesises it — so the level reflects endogenous production as much as olive oil, and a high value on a low-fat diet points at active lipogenesis rather than intake. Read beside palmitic acid. Percentages depend on which fatty acids the panel counts, so compare only within one laboratory.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell levels measured by one laboratory method in 17 cohorts (Italy, Spain, Germany, Canada, United States, Japan, Korea; 167,347 people). Cohort means only: the paper gives no percentiles or reference interval. Oleic acid (C18:1n9) means: 13.5% to 16.5% in most cohorts, 18.9% in Italy and 17.6% in Spain. All lie inside the optimal band of 10 to 20%; no edge is supported.
  • Using an erythrocyte fatty acid fingerprint to predict risk of all-cause mortality: the Framingham Offspring Cohort — McBurney MI, Tintle NL, Vasan RS, et al. — The American Journal of Clinical Nutrition, 2021 · Peer-reviewed publicationFramingham Offspring, 2,240 adults, 27 red cell fatty acids as percent of total. Only myristic, palmitoleic, behenic acid and the Omega-3 Index predicted all-cause death; oleic acid did not. Supports the statement that there is no outcome-linked threshold.

Last reviewed: November 9, 2026 · Oleic acid on its own page

Oleic Acid (C18:1 n-9, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Oleic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Usually the largest monounsaturated fraction on a serum panel. Not essential (the body synthesises it), so a high value on a low-fat diet points at active lipogenesis rather than at olive oil. Read beside palmitic acid. No band is shown because no guideline sets one. Mayo Clinic Laboratories reports 650 to 3,500 nmol/mL for fasting adults in serum, a more than fivefold span that applies to that method only; read the result against the range printed on the client's own report.

Sources

Last reviewed: November 9, 2026

Gondoic Acid (C20:1 n-9, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Gondoic (eicosenoic) acid, the omega-9 fatty acid made by lengthening oleic acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Gondoic acid is a 20-carbon omega-9 monounsaturated fatty acid. Evidence is very limited: in one German cohort of cardiac patients, higher red-cell gondoic acid went with slightly higher all-cause mortality (about 7% per standard deviation), in women only, and nothing was found for serum concentrations. No reference interval was found for serum either. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

  • Individual omega-9 monounsaturated fatty acids and mortality-The Ludwigshafen Risk and Cardiovascular Health Study — Delgado GE, Krämer BK, Lorkowski S, et al. — Journal of Clinical Lipidology, 2017 · Peer-reviewed publicationGerman cohort of 3259 patients referred for coronary angiography, fatty acids measured in red blood cells: each 1-SD higher gondoic acid (GA) went with higher all-cause mortality, hazard ratio 1.07 (1.01 to 1.13); in sex-specific analysis the association held in women only, over a median 10 years. A red-cell percentage in a cardiac-patient cohort, so it gives a direction, not a serum cut-off.

Last reviewed: November 9, 2026

Nervonic Acid (C24:1 n-9, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Nervonic acid, a very-long-chain omega-9 fatty acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Nervonic acid is a 24-carbon omega-9 monounsaturated fatty acid. The outcome evidence does not show that more is better: in a German cohort of cardiac patients, higher red-cell nervonic acid went with higher all-cause mortality (about 12% per standard deviation) and with markers of inflammation and heart failure. For scale, one US reference laboratory reports 60 to 100 nmol/mL in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

  • Individual omega-9 monounsaturated fatty acids and mortality-The Ludwigshafen Risk and Cardiovascular Health Study — Delgado GE, Krämer BK, Lorkowski S, et al. — Journal of Clinical Lipidology, 2017 · Peer-reviewed publicationGerman cohort of 3259 patients referred for coronary angiography, fatty acids measured in red blood cells: each 1-SD higher nervonic acid (NA) went with higher all-cause mortality, hazard ratio 1.12 (1.05 to 1.20); it was the only omega-9 acid associated with higher risk in men, over a median 10 years. A red-cell percentage in a cardiac-patient cohort, so it gives a direction, not a serum cut-off.
  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for nervonic acid, C24:1: 60 to 100 nmol/mL. One laboratory's interval, cited for scale only. The page gives no interpretation for this acid.

Last reviewed: November 9, 2026

Saturated8 markers

Palmitic Acid (C16:0, RBC)Published reference intervalAssay-dependent%

The most abundant saturated fatty acid in the body and in most diets, measured as a share of membrane fatty acids.

UnitOptimalSufficientOut of range
%20 – 3015 – 35below 15 or above 35

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No published reference interval or clinical threshold exists for red cell palmitic acid in percent; the bands are Sera's own. Cohort averages measured by one method across seven countries were 20.9% to 24.0%, so a result a little below 20% is ordinary. The outer edges of 15% and 35% have no source. Largely produced by de novo lipogenesis from excess carbohydrate rather than eaten, so the membrane level tracks metabolic state more closely than saturated fat intake — which is why cutting dietary saturated fat may not move it. In the Framingham Offspring cohort palmitic acid did not predict death, while palmitoleic acid, the lipogenesis marker made from it, did. Percentages depend on which fatty acids the panel counts, so compare only within one laboratory.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell levels measured by one laboratory method in 17 cohorts (Italy, Spain, Germany, Canada, United States, Japan, Korea; 167,347 people). Cohort means only: the paper gives no percentiles or reference interval. Palmitic acid (C16:0) means: 20.9% to 22.2% in the ten US cohorts, 21.9% to 24.0% elsewhere (Canada 23.5%). All lie inside the optimal band of 20 to 30%; no edge is supported.
  • Using an erythrocyte fatty acid fingerprint to predict risk of all-cause mortality: the Framingham Offspring Cohort — McBurney MI, Tintle NL, Vasan RS, et al. — The American Journal of Clinical Nutrition, 2021 · Peer-reviewed publicationFramingham Offspring, 2,240 adults, 27 red cell fatty acids as percent of total. Only myristic, palmitoleic, behenic acid and the Omega-3 Index predicted all-cause death; palmitic acid did not, though it correlated (0.62) with palmitoleic acid. Supports the statement that there is no outcome-linked threshold.

Last reviewed: November 9, 2026 · Palmitic acid on its own page

Stearic Acid (C18:0, RBC)Published reference intervalAssay-dependent%

A long-chain saturated fatty acid found in meat, dairy and cocoa butter.

UnitOptimalSufficientOut of range
%10 – 208 – 25below 8 or above 25

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No published reference interval or clinical threshold exists for red cell stearic acid in percent; the bands are Sera's own. They are consistent with cohort averages measured by one method across seven countries, 13.7% to 18.2%. The outer edges of 8% and 25% have no source. Largely desaturated to oleic acid in the liver and without palmitic acid's effect on LDL cholesterol, so a high stearic acid is not read the way a high palmitic acid is. Percentages depend on which fatty acids the panel counts, so compare only within one laboratory.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell levels measured by one laboratory method in 17 cohorts (Italy, Spain, Germany, Canada, United States, Japan, Korea; 167,347 people). Cohort means only: the paper gives no percentiles or reference interval. Stearic acid (C18:0) means: 14.3% to 17.8% outside the US, 13.7% to 18.2% in the US cohorts (Canada 17.8%, Framingham Offspring 18.1%). All lie inside the optimal band of 10 to 20%; no edge is supported.
  • Using an erythrocyte fatty acid fingerprint to predict risk of all-cause mortality: the Framingham Offspring Cohort — McBurney MI, Tintle NL, Vasan RS, et al. — The American Journal of Clinical Nutrition, 2021 · Peer-reviewed publicationFramingham Offspring, 2,240 adults, 27 red cell fatty acids as percent of total. Only myristic, palmitoleic, behenic acid and the Omega-3 Index predicted all-cause death; stearic acid did not. Supports the statement that there is no outcome-linked threshold.

Last reviewed: November 9, 2026 · Stearic acid on its own page

Palmitic Acid (C16:0, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Palmitic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Largely produced by de novo lipogenesis from excess carbohydrate rather than eaten, so the level tracks metabolic state more closely than saturated fat intake. Cutting dietary saturated fat may not move it. No band is shown because no guideline sets one. Mayo Clinic Laboratories reports 1,480 to 3,730 nmol/mL for fasting adults in serum; that interval applies to that method only, and a concentration rises with total serum lipid, so read the result against the range printed on the client's own report.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for palmitic acid: 1,480 to 3,730 nmol/mL. It is one laboratory's interval, cited to show a range exists for this method, not as a band Sera applies.

Last reviewed: November 9, 2026

Stearic Acid (C18:0, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Stearic acid measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Largely desaturated to oleic acid in the liver and without palmitic acid's effect on LDL cholesterol, so a high stearic acid is not read the way a high palmitic acid is. No band is shown because no guideline sets one. Mayo Clinic Laboratories reports 590 to 1,170 nmol/mL for fasting adults in serum; that interval applies to that method only, so read the result against the range printed on the client's own report.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for stearic acid: 590 to 1,170 nmol/mL. It is one laboratory's interval, cited to show a range exists for this method, not as a band Sera applies.

Last reviewed: November 9, 2026

Myristic Acid (C14:0, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Myristic acid, a 14-carbon saturated fatty acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Myristic acid is a 14-carbon saturated fatty acid. It belongs to the even-chain saturated group (with palmitic and stearic acid) that was associated with about 24% more coronary heart disease per standard deviation in a large European cohort; it has not been shown to carry that risk on its own. For scale, one US reference laboratory reports 30 to 450 nmol/mL in adult serum, a fifteenfold span. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

Last reviewed: November 9, 2026

Arachidic Acid (C20:0, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Arachidic acid, a 20-carbon saturated fatty acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Arachidic acid is a very-long-chain saturated fatty acid, and it behaves differently from palmitic acid: in a pooled analysis of 12 cohorts, people with higher circulating levels had less incident type 2 diabetes (relative risk 0.78 for the 90th versus the 10th percentile). That association disappeared once palmitic acid and triglycerides were accounted for, so it may not be independent of them. For scale, one US reference laboratory reports 50 to 90 nmol/mL in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

Last reviewed: November 9, 2026

Behenic Acid (C22:0, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Behenic acid, a 22-carbon saturated fatty acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Behenic acid is a very-long-chain saturated fatty acid, and it behaves differently from palmitic acid: in a pooled analysis of 12 cohorts, people with higher circulating levels had less incident type 2 diabetes (relative risk 0.84 for the 90th versus the 10th percentile). That association disappeared once palmitic acid and triglycerides were accounted for, so it may not be independent of them. For scale, one US reference laboratory reports up to 96.3 nmol/mL in serum, with no lower limit. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

  • Associations of circulating very-long-chain saturated fatty acids and incident type 2 diabetes: a pooled analysis of prospective cohort studies — Fretts AM, Imamura F, Marklund M, et al. — The American Journal of Clinical Nutrition, 2019 · Peer-reviewed publicationPooled analysis of 12 FORCE cohorts (51,431 participants, 14,276 incident diabetes cases): the relative risk of diabetes comparing the 90th with the 10th percentile of circulating behenic acid (22:0) was 0.84 (0.77 to 0.91). The association disappeared after adjustment for circulating palmitic acid and triglycerides. It reports relative risks across each cohort's own distribution, not a cut-off.
  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceSerum reference interval for docosanoic (behenic) acid, C22:0: 0.0 to 96.3 nmol/mL, with no lower limit and no age split. One laboratory's interval, cited for scale only; on this profile the very-long-chain acids serve the work-up of peroxisomal disorders.

Last reviewed: November 9, 2026

Lignoceric Acid (C24:0, Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

Lignoceric acid, a 24-carbon saturated fatty acid, measured as a concentration in serum.

No universal Sera range published.

Concentration depends on which lipid fraction the laboratory quantifies, and reports rarely say which. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Lignoceric acid is a very-long-chain saturated fatty acid, and it behaves differently from palmitic acid: in a pooled analysis of 12 cohorts, people with higher circulating levels had less incident type 2 diabetes (relative risk 0.75 for the 90th versus the 10th percentile). That association disappeared once palmitic acid and triglycerides were accounted for, so it may not be independent of them. One US reference laboratory reports up to 91.4 nmol/mL in serum and notes that raised C24:0 together with C26:0 is seen in peroxisomal disorders such as X-linked adrenoleukodystrophy, which is a medical work-up and not a nutritional reading. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

  • Associations of circulating very-long-chain saturated fatty acids and incident type 2 diabetes: a pooled analysis of prospective cohort studies — Fretts AM, Imamura F, Marklund M, et al. — The American Journal of Clinical Nutrition, 2019 · Peer-reviewed publicationPooled analysis of 12 FORCE cohorts (51,431 participants, 14,276 incident diabetes cases): the relative risk of diabetes comparing the 90th with the 10th percentile of circulating lignoceric acid (24:0) was 0.75 (0.69 to 0.83). The association disappeared after adjustment for circulating palmitic acid and triglycerides. It reports relative risks across each cohort's own distribution, not a cut-off.
  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceSerum reference interval for tetracosanoic (lignoceric) acid, C24:0: 0.0 to 91.4 nmol/mL, an upper limit only. The page states that increased serum C24:0 and C26:0 are seen in peroxisomal disorders, X-linked adrenoleukodystrophy, adrenomyeloneuropathy and Zellweger syndrome. One laboratory's interval, cited for scale only.

Last reviewed: November 9, 2026

Trans1 marker

Trans Fat IndexFunctional / longevity targetAssay-dependent%

The combined share of industrially produced trans fatty acids in red blood cell membranes.

UnitOptimalSufficientOut of range
%0 – 11 – 2below 0 or above 2

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The one fatty acid with no requirement and no beneficial level, so lower is unambiguously better and public-health guidance is unambiguous with it. One caveat on the figure: WHO's 1% is a share of total dietary ENERGY, while this band is a share of membrane fatty acids — the same number attached to a different quantity, so the guidance supports the direction rather than the exact edge. Levels have fallen sharply where partial hydrogenation was banned, so a raised value now usually points at imported processed or fried food. The 1% edge has peer-reviewed support as a red cell figure: a Health Canada analysis of the Canadian Health Measures Survey compares against a proposed threshold of 1% of total red cell fatty acids. It is a proposed research threshold and not a guideline one. The 2% edge has no source.

Sources

  • Proportions of trans fatty acids in erythrocytes of Canadian adults before the prohibition of partially hydrogenated oils in foods: results from the Canadian Health Measures Survey 2012-2015 — Demonty I, Nguyen L, MacFarlane AJ, et al. — The American Journal of Clinical Nutrition, 2024 · Peer-reviewed publicationNationally representative Canadian survey, 4,025 adults: mean total red cell trans fat 0.59% of total fatty acids, described as low against a proposed threshold of 1% above which cardiovascular risk may be higher. Matches Sera's optimal upper edge of 1%.
  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell levels measured by one laboratory method in 17 cohorts (Italy, Spain, Germany, Canada, United States, Japan, Korea; 167,347 people). Cohort means only: the paper gives no percentiles or reference interval. Total trans means: 0.59% in Canada, 0.66% in Italy, 0.96% in the German LURIC cohort, 0.77% to 0.91% in US laboratory cohorts from 2011 to 2019, and 2.10% to 2.70% in older US cohorts. Shows that 1% now separates current from pre-ban levels; does not support the 2% edge as a threshold.
  • REPLACE action package and guideline on saturated and trans-fatty acid intake — World Health Organization, 2023 · Government / public-health guidanceEstablishes that industrially produced trans fat should be eliminated from the food supply, and that total trans fat intake should stay below 1% of total energy. Read the quantity carefully: that is a DIETARY INTAKE threshold, not a red cell membrane percentage. Sera's band edge is a different measurement that happens to share the figure, so the source supports the direction — lower is unambiguously better, with no beneficial level — rather than the exact edge.

Last reviewed: November 9, 2026 · Trans Fat Index on its own page

Whole-profile composition11 markers

Omega-3 Total (All Omega-3s, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

The share of every omega-3 fatty acid the panel measured, usually ALA, EPA, DPA and DHA, in the fatty acids of plasma. Broader than the plasma Omega-3 Index (EPA and DHA) and the EPA+DPA+DHA total.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and which omega-3s are summed differs between panels. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The plasma omega-3 total is the share of every omega-3 acid the panel measured, usually ALA, EPA, DPA and DHA, in the fatty acids of plasma. Plasma fatty acids turn over in days to a couple of weeks, so the result moves with recent meals and supplements and is a short-term reading, unlike a red cell total. Which acids are summed differs between panels. No guideline or reference laboratory has set a plasma range, and the US National Institutes of Health states that experts have not established normal ranges for omega-3s in plasma, so Sera records the value without a band. In large European cohorts a higher circulating omega-3 share went with fewer coronary events, but no cut-off was defined. Sera's band for the omega-3 total is written for red cell panels and does not apply here.

Sources

Last reviewed: November 9, 2026

Omega-6 Total (All Omega-6s, Plasma/Serum, %)No universal rangeUnbandedAssay-dependent% · unbanded

The share of every omega-6 fatty acid the panel measured, mostly linoleic acid with arachidonic acid and smaller amounts of others, in the fatty acids of plasma.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and which omega-6s are summed differs between panels. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The plasma omega-6 total is the share of every omega-6 acid the panel measured in the fatty acids of plasma. Linoleic acid makes up most of it, so it largely reflects recent intake of seed oils, nuts and grains. Plasma fatty acids turn over in days to a couple of weeks, so it is a short-term reading, unlike a red cell total. Which acids are summed differs between panels: one US laboratory sums six. No guideline or reference laboratory has set a plasma range, so Sera records the value without a band. Sera's band for the omega-6 total is written for red cell panels and does not apply here.

Sources

  • OmegaCheck: Test Guide (content reviewed 9/2025) — Quest Diagnostics, 2025 · Laboratory / reference-interval sourceQuest's guide defines the ratio as the sum of six omega-6 fatty acids divided by the sum of three omega-3 fatty acids (EPA, DPA, DHA), and says a high ratio should be interpreted with caution because it does not separate acids with different effects.

Last reviewed: November 9, 2026

Omega-3 Total (% of Total Fatty Acids)Functional / longevity targetAssay-dependent%

The share of all omega-3 fatty acids — EPA, DHA, DPA and ALA — in total fatty acids. Broader than the Omega-3 Index, which counts only EPA and DHA.

UnitOptimalSufficientOut of range
%10 – 168 – 20below 8 or above 20

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No published threshold exists for total omega-3 as a percentage of red cell fatty acids; the bands are a functional translation of the Omega-3 Index targets and have no source of their own. Bands sit above those for the Omega-3 Index deliberately, because this marker counts every omega-3 — EPA, DHA, DPA and ALA — where the Index counts two. In cohorts measured by one method the total ran about 2 to 3 points above the Index on average, so the Index target of 8% corresponds to a total of roughly 10 to 11%, and the Index's lowest category of 4% to roughly 6 to 7%. The upper edges of 16% and 20% have no evidence behind them. The outcome data are for EPA and DHA, which is the Index, not for the total. Which acids a panel sums into the total varies, so compare across draws only on the same panel.

Sources

Last reviewed: November 9, 2026 · Total omega-3 % on its own page

Omega-6 Total (% of Total Fatty Acids)Exploratory indexAssay-dependent%

The share of every omega-6 fatty acid measured — linoleic, arachidonic, DGLA and GLA together — in total fatty acids.

UnitOptimalSufficientOut of range
%28 – 3625 – 40below 25 or above 40

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No published threshold exists for total omega-6 as a percentage of red cell fatty acids; the bands reflect typical levels, about 31 to 34% in European and North American cohorts when the individual omega-6 acids are added up, and have no outcome evidence behind them. Dominated by linoleic and arachidonic acid, so it largely restates those figures. Read it as the other half of the omega balance beside the omega-3 percentage; neither number carries much on its own. A high value is not established as harmful: in pooled cohort data higher linoleic acid in blood or tissue went with lower cardiovascular mortality, and arachidonic acid was not linked to higher risk. Which acids a panel sums into the total varies, so compare only within one laboratory.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell levels measured by one laboratory method in 17 cohorts (Italy, Spain, Germany, Canada, United States, Japan, Korea; 167,347 people). Cohort means only: the paper gives no percentiles or reference interval. The omega-6 means (linoleic 11.1% to 13.8% and arachidonic 13.9% to 16.8% in Western cohorts, plus DGLA, 22:4 and 22:5) sum to about 31 to 34% in European and North American cohorts and 28% in Japan. Shows the optimal band matches typical levels; supports no edge as a threshold.

Last reviewed: November 9, 2026 · Total omega-6 % on its own page

MUFA Total (% of Total Fatty Acids)Exploratory indexOne-sidedAssay-dependent%

The share of monounsaturated fatty acids — oleic, palmitoleic, vaccenic, gondoic and nervonic — in total fatty acids.

UnitOptimalSufficientOut of range
%16 – 2214 – 26above 26

Bounded on the high side only — a low result is not treated as out of range. No source gives a lower limit and ordinary cohort means sit at the current lower edges.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No published threshold exists for total MUFA as a percentage of red cell fatty acids; the bands are Sera's own and have no source. In cohorts measured by one method the monounsaturated acids added up to about 15 to 16% in US and German cohorts and 19 to 21% in Spanish and Italian ones, so a result near the lower edges is ordinary. Reflects monounsaturated fat eaten and monounsaturated fat made, and this number cannot separate them. Read beside oleic acid, which dominates it, and palmitoleic acid, which tracks de novo lipogenesis more specifically. Which acids a panel sums into the total varies, so compare only within one laboratory.

Sources

  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell levels measured by one laboratory method in 17 cohorts (Italy, Spain, Germany, Canada, United States, Japan, Korea; 167,347 people). Cohort means only: the paper gives no percentiles or reference interval. Oleic acid, which dominates MUFA, averaged 13.5% to 16.5% in most cohorts and 17.6% to 18.9% in Spain and Italy; with palmitoleic, 20:1 and 24:1 added the total is about 15 to 21%. Supports no edge; shows the lower edges of 14% and 16% sit at ordinary levels.

Last reviewed: November 9, 2026

SFA Total (% of Total Fatty Acids)Exploratory indexOne-sidedAssay-dependent%

The share of saturated fatty acids — palmitic, stearic, myristic and the longer chains — in total fatty acids.

UnitOptimalSufficientOut of range
%36 – 4034 – 44above 44

Bounded on the high side only — a low result is not treated as out of range. No source supports a lower edge, and the UK Biobank mean for total plasma is 34.0%.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Tracks de novo lipogenesis as much as saturated fat intake, because the body makes palmitic acid from excess carbohydrate — so a high SFA% is read against glucose, insulin and triglycerides rather than against the diet history. Observational data link higher values to cardiovascular and metabolic risk, with no universal threshold. These bands have no published cut-off behind them. In large UK cohorts measuring total plasma or serum the average was 34 to 37%; in the plasma phospholipid fraction it was about 46%, so check which fraction the laboratory measured before reading the band. Nothing found links a low SFA% to harm.

Sources

Last reviewed: November 9, 2026

PUFA Total (% of Total Fatty Acids)Exploratory indexAssay-dependent%

The share of polyunsaturated fatty acids — every omega-3 and omega-6 together — in total fatty acids.

UnitOptimalSufficientOut of range
%40 – 4535 – 50below 35 or above 50

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The sum of omega-3% and omega-6%, so it is a check on those two rather than independent information. A low PUFA% points at low essential fatty acid intake overall; which family is short shows in the two figures beneath it. No guideline or laboratory interval gives a threshold for polyunsaturated fat as a percentage of total fatty acids, so none of the four edges has a source. Published cohort means differ by several points between cohorts and lipid fractions (about 37 to 43%).

Sources

Last reviewed: November 9, 2026

Total Fatty Acids (Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

The sum of every fatty acid the panel measured, as a concentration.

No universal Sera range published.

A sum whose constituents vary by panel, over a concentration whose lipid fraction varies by laboratory. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The sum of every fatty acid the panel measures. No study was found that links this total to an outcome in its own right. For scale, one US reference laboratory reports 7.3 to 16.8 mmol/L in adult serum and requires a 12 to 14 hour fast for nutritional assessment. No threshold exists, and the figure depends on which acids the laboratory includes and the lipid fraction it measures, so compare results only within one laboratory.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 and over) serum reference interval for total fatty acids: 7.3 to 16.8 mmol/L, with a 12 to 14 hour fast required for nutritional assessment. One laboratory's interval for its own list of acids, cited for scale only.

Last reviewed: November 9, 2026

Total Monounsaturated Fatty Acids (Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

The sum of the monounsaturated fatty acids measured on the panel, as a concentration.

No universal Sera range published.

A sum whose constituents vary by panel, over a concentration whose lipid fraction varies by laboratory. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The sum of the monounsaturated fatty acids. It is a poor guide to olive oil or other dietary MUFA intake, because much of the circulating MUFA is made in the body from saturated fat; in three large European cohorts a higher MUFA share was associated with higher cardiovascular mortality, not lower. For scale, one US reference laboratory reports 1.3 to 5.8 mmol/L in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

Last reviewed: November 9, 2026

Total Saturated Fatty Acids (Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

The sum of the saturated fatty acids measured on the panel, as a concentration.

No universal Sera range published.

A sum whose constituents vary by panel, over a concentration whose lipid fraction varies by laboratory. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The sum of the saturated fatty acids. A higher saturated share was associated with higher cardiovascular risk in three large European cohorts, but the sum hides opposite signals: even-chain acids (myristic, palmitic, stearic) carried the risk, while odd-chain acids went with lower risk and the longer-chain acids (20:0 to 24:0) with lower stroke risk. For scale, one US reference laboratory reports 2.5 to 5.5 mmol/L in adult serum. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

Last reviewed: November 9, 2026

Total Polyunsaturated Fatty Acids (Plasma/Serum, concentration)No universal rangeUnbandedAssay-dependentμmol/L · mg/L · μg/mL · mg/dL · unbanded

The sum of the polyunsaturated fatty acids measured on the panel, as a concentration.

No universal Sera range published.

A sum whose constituents vary by panel, over a concentration whose lipid fraction varies by laboratory. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The sum of the omega-3 and omega-6 fatty acids, dominated by omega-6, so it adds little beyond those two totals. In three large European cohorts a higher omega-3 share went with less coronary heart disease and a higher omega-6 share with less stroke; nothing found supports reading a high total as a problem. For scale, one US reference laboratory reports 3.2 to 5.8 mmol/L in adult serum, of which omega-6 is 3.0 to 5.4. No threshold exists, and the figure depends on the lipid fraction the laboratory measures (total serum, phospholipid or whole blood), so compare results only within one laboratory.

Sources

Last reviewed: November 9, 2026

Ratios and indices6 markers

Omega-6:Omega-3 Ratio (AA:EPA)Functional / longevity targetratio

The balance between arachidonic acid, an omega-6 fat, and EPA, an omega-3 fat. Two specific fatty acids, not every omega-6 against every omega-3 — that broader measure is the Total Omega-6:Omega-3 Ratio.

UnitOptimalSufficientOut of range
ratio1 – 31 – 6below 1 or above 6

Interpretation: Functional-medicine consensus supports 1 to 3:1 as the anti-inflammatory target. The mechanism is sound — the two families compete for the same desaturase and elongase enzymes, so the balance matters more than either intake alone — but outcome data are considerably less robust than for the Omega-3 Index. This is the eicosanoid ratio, arachidonic acid against EPA; the Total Omega-6:Omega-3 Ratio is the dietary-pattern version and runs several times higher in the same person. No published source states 1 to 3 or 6 for the red cell AA:EPA ratio. Dividing published cohort means gives about 14 to 26 in most Western populations and about 6 in Japan, so the average Western result reads Out of range here while reading Sufficient on the Omega-3 Index. Read this ratio as a functional target and the Index as the better-evidenced measure.

Sources

  • MDX_Report_Omega3_ENG.pdf (laboratory sample report for a dried blood spot omega-3 test; the exact report title could not be read from the file) — Mosaic Diagnostics (formerly Great Plains Laboratory); the report refers readers to omegaquant.com for its references, 2017 · Functional-medicine referenceLaboratory report table derived from about 8,900 dried blood samples. AA:EPA 2.5 to 11 is desirable (matching an Omega-3 Index of 8 to 12%), 11 to 25 intermediate (Index 4 to 8%), over 25 undesirable (Index below 4%), below 2.5 elevated. Sera's 1 to 3 and 6 do not match. Dried blood spot, not washed red cells, and a commercial report, not a guideline.
  • Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell arachidonic acid was 14 to 17% in the Western cohorts and EPA 0.43 to 1.06%, which puts the average AA:EPA at roughly 14 to 26 in most of them (39 in one); in Japan, Korea and Alaska (EPA 1.9 to 2.2%, AA about 12%) it is about 6. The ratio itself is not reported; these are divisions of the published means.
  • The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases — Simopoulos AP — Experimental Biology and Medicine, 2008 · Peer-reviewed publicationArgues that the two families compete for the same desaturase and elongase enzymes, so the balance between them matters and not the absolute intake of either. Sets out the low single-figure ratio widely used as a functional target against the 15:1 or higher typical of Western diets. The mechanism is well described; the specific target figure is consensus rather than an outcome-validated threshold.

Last reviewed: November 9, 2026 · AA:EPA ratio on its own page

Total Omega-6:Omega-3 RatioFunctional / longevity targetAuto-calculatedOne-sidedratio

Every omega-6 fatty acid measured, divided by every omega-3 fatty acid measured.

Auto-calculated

(LA + AA + DGLA + GLA) / (EPA + DHA + ALA + DPA)

Calculated when LA (C18:2 n-6, RBC) and AA (C20:4 n-6, RBC) and EPA (C20:5 n-3, RBC) and DHA (C22:6 n-3, RBC) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio2 – 42 – 6above 6

Bounded on the high side only — a low result is not treated as out of range. No source gives a lower limit and a low ratio only reflects high omega-3 status.

Interpretation: Functional-medicine consensus supports a total omega-6 to omega-3 ratio around 2 to 4:1, against the 10 to 20:1 or higher typical of Western diets; those figures describe diet, and no published source sets them for red cells. The mechanism is well described: the two families compete for the same desaturase and elongase enzymes. In UK Biobank a higher plasma ratio went with higher mortality, but no threshold came out of it. Worked from published cohort averages, this red cell ratio sits at about 3.5 to 4.3 in North American and southern European groups whose Omega-3 Index is low, so an Optimal result here does not mean omega-3 status is adequate: read the Omega-3 Index first. This is the dietary-pattern version of the balance; AA:EPA is the eicosanoid version and the two are not interchangeable. Sera sums only the fatty acids present on the panel, so the number is comparable across draws only when the same panel was run.

Sources

Last reviewed: November 9, 2026 · Omega-6 to omega-3 ratio on its own page

AA/EPA Ratio (Plasma/Serum)No universal rangeUnbandedAssay-dependentratio · unbanded

Arachidonic acid divided by EPA, both as shares of the fatty acids in plasma. Two specific fatty acids, not every omega-6 against every omega-3.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The plasma AA to EPA ratio divides the arachidonic acid share by the EPA share. A higher ratio means less EPA relative to arachidonic acid. Because EPA in plasma moves quickly with recent fish and capsules, this ratio swings more from week to week than the red cell version. No guideline or reference laboratory has set a plasma threshold, so Sera records the value without a band. One US laboratory prints 3.7 to 40.7 for its whole blood test, a population range rather than a target. Laboratories report the ratio either way up (AA to EPA or EPA to AA), so check the direction. Read it beside the red cell AA to EPA ratio where both were measured.

Sources

  • OmegaCheck (test mnemonic OMEGAC) — Cleveland Clinic Laboratories (performed by Cleveland HeartLab, Inc.), 2026 · Laboratory / reference-interval sourceCleveland HeartLab's OmegaCheck interval for EPA: 0.2 to 2.3% by weight. The test is collected as EDTA whole blood and analysed by LC-MS/MS. One laboratory's interval for a whole blood method.
  • OmegaCheck: Test Guide (content reviewed 9/2025) — Quest Diagnostics, 2025 · Laboratory / reference-interval sourceQuest's guide defines the ratio as the AA percentage divided by the EPA percentage and states that a higher ratio is associated with higher risk of major coronary events. The cited study (Itakura 2011) is Japanese and pre-2016, so it supports direction only.
  • OmegaCheck® (test code 92701) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceQuest's own directory entry for OmegaCheck: the preferred specimen is EDTA whole blood, not centrifuged, analysed by LC/MS/MS. The reference range field reads 'See Laboratory Report'. This is why the OmegaCheck intervals below describe a whole blood test, not a plasma one.

Last reviewed: November 9, 2026

Omega-6/Omega-3 Ratio (Plasma/Serum)No universal rangeUnbandedAssay-dependentratio · unbanded

The summed omega-6 fatty acids divided by the summed omega-3 fatty acids, as shares of the fatty acids in plasma.

No universal Sera range published.

No guideline or reference laboratory publishes a plasma percentage interval, and the one laboratory interval that exists is a whole blood method's own population range. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The plasma omega-6 to omega-3 ratio divides the summed omega-6 acids by the summed omega-3 acids in plasma. Linoleic acid dominates the top, so the ratio runs several times higher than the AA to EPA ratio. Laboratories differ in which acids they sum, and one US laboratory counts only EPA, DPA and DHA on the omega-3 side. Plasma fatty acids turn over in days to a couple of weeks, so a plasma result moves with recent meals and supplements and is a short-term reading, unlike the red cell value, which reflects the last two to three months. No guideline or reference laboratory has set a plasma threshold, so Sera records the value without a band. That laboratory prints 3.7 to 14.4 for its whole blood test, a population range rather than a target. Check which way up the ratio is printed.

Sources

  • OmegaCheck (test mnemonic OMEGAC) — Cleveland Clinic Laboratories (performed by Cleveland HeartLab, Inc.), 2026 · Laboratory / reference-interval sourceCleveland HeartLab's OmegaCheck interval for EPA: 0.2 to 2.3% by weight. The test is collected as EDTA whole blood and analysed by LC-MS/MS. One laboratory's interval for a whole blood method.
  • OmegaCheck: Test Guide (content reviewed 9/2025) — Quest Diagnostics, 2025 · Laboratory / reference-interval sourceQuest's guide defines the ratio as the sum of six omega-6 fatty acids divided by the sum of three omega-3 fatty acids (EPA, DPA, DHA), and says a high ratio should be interpreted with caution because it does not separate acids with different effects.
  • OmegaCheck® (test code 92701) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceQuest's own directory entry for OmegaCheck: the preferred specimen is EDTA whole blood, not centrifuged, analysed by LC/MS/MS. The reference range field reads 'See Laboratory Report'. This is why the OmegaCheck intervals below describe a whole blood test, not a plasma one.

Last reviewed: November 9, 2026

AA/DHA RatioNo universal rangeUnbandedAssay-dependentratio · unbanded

Arachidonic acid divided by DHA, as printed by some serum fatty acid panels.

No universal Sera range published.

Published intervals span nearly the whole plausible range, so no band would separate a normal result from a raised one. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: No band is shown because no guideline or laboratory directory publishes an adult interval for this ratio. The laboratories that print reference intervals give them for arachidonic acid and DHA separately: at Mayo Clinic Laboratories, 520 to 1,490 nmol/mL and 30 to 250 nmol/mL in adult serum, which leaves ratios from about 2 to about 50 compatible with both being in range. Read the Omega-3 Index for omega-3 status, and compare this figure only against the client's own earlier results from the same laboratory.

Sources

  • FAPCP - Overview: Fatty Acid Profile, Comprehensive (C8-C26), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult serum intervals for the two constituents: arachidonic acid 520 to 1,490 nmol/mL and DHA 30 to 250 nmol/mL. No AA/DHA ratio is reported. Cited to show that both constituents can be in range across a very wide span of ratios.

Last reviewed: November 9, 2026

AA/DGLA Ratio (Delta-5 Desaturase Index)No universal rangeAuto-calculatedUnbandedratio · unbanded

Arachidonic acid divided by dihomo-gamma-linolenic acid, used as an index of delta-5 desaturase activity.

Auto-calculated

Arachidonic acid / DGLA (both from the same compartment)

Calculated when AA (C20:4 n-6, RBC) and DGLA (C20:3 n-6, RBC) are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

No universal Sera range published.

No published threshold exists, and studies disagree on which direction carries the risk. Read this marker against the interval printed by the issuing laboratory.

Interpretation: An index of delta-5 desaturase activity, the step that converts DGLA into arachidonic acid. In cohort data it is a low ratio that goes with insulin resistance: in the German EPIC-Potsdam study higher DGLA predicted more type 2 diabetes and a higher ratio predicted less, and reviews report lower delta-5 desaturase activity in obesity. A low ratio is therefore read beside glucose, insulin, triglycerides and the transaminases. The ratio is also set partly by inherited FADS gene variants, and a genetic (Mendelian randomisation) analysis pointed the other way without being able to separate this enzyme from delta-6 desaturase, so cause and effect are unsettled. No guideline, laboratory or cohort publishes a cut-off, and the value differs between serum, phospholipid and red cell measurements, so no band is shown; compare it against the client's own earlier results from the same laboratory. Sera computes it from whichever compartment carries both fatty acids, and defers to the ratio the laboratory printed when there is one.

Sources

Last reviewed: November 9, 2026

Vitamins & Minerals · 18 markers

Essential nutrients that support overall health and metabolic function

Vitamin D3 (25-Hydroxy Vitamin D)Functional / longevity targetng/mL · μg/L · nmol/L

The main form of vitamin D that circulates in your blood.

UnitOptimalSufficientOut of range
ng/mL50 – 8030 – 100below 30 or above 100
μg/L50 – 8030 – 100below 30 or above 100
nmol/L125 – 20075 – 250below 75 or above 250

Interpretation: The optimal band of 50 to 80 ng/mL (125 to 200 nmol/L) is a functional target, widely used in functional and integrative practice, and it sits above what mainstream bodies recommend. The US National Academies consider 20 ng/mL (50 nmol/L) sufficient for most people and note possible adverse effects above 50, and Mayo Clinic Laboratories lists 51 to 80 ng/mL as carrying an increased risk of hypercalciuria. The 2024 Endocrine Society guideline found no clear evidence defining an optimal level. Sera's acceptable band starts at 30 ng/mL, where the older Endocrine Society guideline placed sufficiency, so a result of 20 to 29 is flagged here though the National Academies would call it adequate. The upper edge of 100 ng/mL is the top of the Labcorp reference range.

Sources

  • Vitamin D - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceStates the National Academies position: 50 nmol/L (20 ng/mL) or more is sufficient for most people, deficiency risk rises below 30 nmol/L (12 ng/mL), and levels above 125 nmol/L (50 ng/mL) can be associated with adverse effects. Supports a sufficient lower edge of 20 and an optimal upper edge of 50 ng/mL. Updated June 27, 2025.
  • 25HDN - 25-Hydroxyvitamin D2 and D3, Serum: Clinical & Interpretive — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceClinical decision values based on the 2011 Institute of Medicine report: below 10 ng/mL severe deficiency, 10 to 19 mild to moderate deficiency, 20 to 50 optimum, 51 to 80 increased risk of hypercalciuria, above 80 toxicity possible. Sera's current optimal band of 50 to 80 is Mayo's caution band.
  • Vitamin D, 25-Hydroxy — Labcorp, 2026 · Laboratory / reference-interval sourcePrints reference ranges of 20.0 to 100.0 ng/mL and 30 to 100 ng/mL, and states deficiency is below 20 ng/mL (Institute of Medicine) with 21 to 29 called insufficiency by the older Endocrine Society guideline. Matches Sera's sufficient band of 30 to 100 and supports the upper edge of 100.

Last reviewed: November 9, 2026 · Vitamin D (25-hydroxy) on its own page

PTH (Parathyroid Hormone) — IntactPublished reference intervalAssay-dependentpg/mL · pmol/L

The hormone that raises blood calcium by acting on bone, kidney and gut, measured as the intact molecule.

UnitOptimalSufficientOut of range
pg/mL15 – 5515 – 65below 15 or above 65
pmol/L1.59 – 5.831.59 – 6.89below 1.59 or above 6.89

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The acceptable band is the adult reference interval used by Mayo Clinic Laboratories and Labcorp, 15 to 65 pg/mL; intervals differ between assays, so the reporting laboratory's own range takes precedence. Not interpretable without a calcium drawn at the same time. High PTH with high calcium suggests primary hyperparathyroidism; high PTH with low or normal calcium is usually secondary, most often to vitamin D deficiency or reduced kidney function; low PTH with low calcium suggests hypoparathyroidism. A PTH near the top of the range with a low vitamin D is the common functional finding, and it resolves with repletion rather than investigation. The narrower optimal band, ending at 55 pg/mL, is a functional target with no published support.

Sources

  • PTH2 - Parathyroid Hormone, Serum: Clinical & Interpretive — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference values of 15 to 65 pg/mL. Matches Sera's sufficient upper edge of 65; Sera's lower edge of 5 is 10 pg/mL below it.
  • Parathyroid Hormone (PTH), Intact — Labcorp, 2026 · Laboratory / reference-interval sourceInterpretation table read against calcium: intact PTH 15 to 65 pg/mL with calcium 8.6 to 10.2 mg/dL is normal; above 65 with high calcium is primary hyperparathyroidism; below 15 with low calcium is hypoparathyroidism.

Last reviewed: November 9, 2026 · Intact PTH on its own page

Vitamin A (Retinol)Published reference intervalμg/dL · μmol/L · μg/mL

The circulating form of vitamin A, essential for vision, epithelial integrity and immune function.

UnitOptimalSufficientOut of range
μg/dL30 – 6020 – 80below 20 or above 80
μmol/L1.05 – 2.090.7 – 2.79below 0.7 or above 2.79
μg/mL0.3 – 0.60.2 – 0.8below 0.2 or above 0.8

Interpretation: The acceptable band starts at 20 μg/dL (0.70 μmol/L), the level at or below which NIH and WHO place vitamin A deficiency, and ends near the top of the Mayo Clinic Laboratories adult reference interval (78 μg/dL). There is no widely accepted serum level that marks toxicity. The narrower optimal band has no outcome evidence behind it. Insensitive to depletion by design of the physiology: the liver holds most of the body's vitamin A and defends the blood level, so retinol stays normal through a long decline and falls only near exhaustion. It also drops during any acute-phase response, so a low retinol with a raised CRP usually reflects inflammation rather than status.

Sources

  • Vitamin A and Carotenoids - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceA serum or plasma retinol of 20 mcg/dL (0.70 micromol/L) or less frequently reflects moderate deficiency and 10 mcg/dL or less severe deficiency. Matches Sera's sufficient lower edge exactly. Updated March 10, 2025.
  • VITA - Vitamin A, Serum: Clinical & Interpretive — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference values 32.5 to 78.0 mcg/dL; WHO recommends supplementation below 20.0 mcg/dL; no widely accepted serum level associated with toxicity. Close to Sera's sufficient upper edge of 80 and optimal lower edge of 30.
  • Vitamin A — Labcorp, 2026 · Laboratory / reference-interval sourceAge-banded adult intervals: 18.9 to 57.3 μg/dL at 20 to 39 years, 20.1 to 62.0 at 40 to 59, 22.0 to 69.5 over 59. The lower limits sit at Sera's sufficient lower edge of 20; the upper limits bracket Sera's optimal upper edge of 60.

Last reviewed: November 9, 2026 · Vitamin A on its own page

Vitamin C (Ascorbic Acid)Published reference intervalOne-sidedmg/dL · μmol/L

Vitamin C measured in plasma.

UnitOptimalSufficientOut of range
mg/dL0.88 – 20.4 – 2below 0.4
μmol/L50 – 11423 – 114below 23

Bounded on the low side only — a high result is not treated as out of range. A high result reflects recent intake or supplements, and no upper limit has a clinical meaning.

Interpretation: The acceptable band starts at 23 μmol/L (0.4 mg/dL), where four laboratories agree (ARUP, Mayo, and two NHS trusts at 26), and deficiency is below about 11 μmol/L. The optimal band starts at 50 μmol/L (0.88 mg/dL), the plasma level the Nordic Nutrition Recommendations 2023, following EFSA, use to define adequate status. That is a public-health adequacy target, not an outcome threshold. High results reflect recent intake and are not flagged. The sample breaks down unless frozen and protected from light, smokers run lower, and an NHS laboratory states that the result is of no value when CRP is raised.

Sources

  • Vitamin C, Plasma (0080380) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceInterval 23 to 114 μmol/L; below 11 μmol/L is deficiency and 11 to 23 a moderate risk of it. Sera's sufficient band in μmol/L.
  • Ascorbic Acid (Vitamin C), Plasma (VITC) — Mayo Clinic Laboratories (performing laboratory), Duke University Hospital test catalog, 2026 · Laboratory / reference-interval source0.4 to 2.0 mg/dL indicates adequate supply. Sera's sufficient band in mg/dL.
  • Vitamin C (test information) — The Rotherham NHS Foundation Trust, Clinical Biochemistry, 2024 · Laboratory / reference-interval sourceUK plasma interval 26 to 85 μmol/L, deficiency below 11.1. Confirms the low edge within 3 μmol/L.
  • Vitamin C (test information) — Bradford and Craven Pathology, Bradford Teaching Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceRepeats the 26 to 85 μmol/L interval and states that the result is of no value when CRP is raised.
  • Nordic Nutrition Recommendations 2023: Vitamin C — Nordic Council of Ministers, 2023 · Government / public-health guidanceUses a target plasma ascorbate of 50 μmol/L, following EFSA, to set the average requirement. The start of Sera's optimal band; an adequacy target, not an outcome threshold.

Last reviewed: November 9, 2026 · Vitamin C on its own page

Vitamin E (Alpha-Tocopherol)Published reference intervalmg/L · μmol/L

The principal circulating form of vitamin E, the main fat-soluble antioxidant in cell membranes.

UnitOptimalSufficientOut of range
mg/L6 – 125.5 – 17below 5.5 or above 17
μmol/L13.9 – 27.912.8 – 39.5below 12.8 or above 39.5

Interpretation: The acceptable band is the adult reference interval of Mayo Clinic Laboratories, 5.5 to 17.0 mg/L; Labcorp's upper limits are higher still and rise with age. The narrower optimal band of 6 to 12 mg/L is a functional target with no published support, and typical community levels sit above it, around 13 to 14 mg/L. Carried on lipoproteins, so the level tracks blood lipids rather than tissue adequacy — someone with high cholesterol can show adequate tocopherol while relatively depleted. Best read as a ratio to total cholesterol. Frank deficiency is rare outside fat malabsorption.

Sources

Last reviewed: November 9, 2026 · Vitamin E on its own page

Coenzyme Q10 (CoQ10)Functional / longevity targetAssay-dependentμg/mL · mg/L · μmol/L

Coenzyme Q10 — ubiquinone and its reduced form ubiquinol — in plasma or serum. It carries electrons in the mitochondrial respiratory chain and is the main fat-soluble antioxidant regenerating vitamin E.

UnitOptimalSufficientOut of range
μg/mL2.5 – 70.43 – 10below 0.43 or above 10
mg/L2.5 – 70.43 – 10below 0.43 or above 10
μmol/L2.9 – 8.110.5 – 11.58below 0.5 or above 11.58

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Published reference intervals sit far below the optimal band: 0.43 to 1.53 μg/mL at Mayo Clinic Laboratories and 0.37 to 2.20 at Labcorp, describing what an unsupplemented population has rather than what is good to have. The acceptable band starts at the Mayo lower limit. The optimal band of 2.5 to 7 μg/mL is a supplementation target used in cardiovascular and endothelial work; it has no current outcome evidence, and the upper edges have no published threshold behind them. There is no established deficiency cut-off. Read it against total cholesterol or LDL in every case: CoQ10 travels on lipoproteins, so a low-cholesterol result drags the CoQ10 number down with it and a high-cholesterol one props it up, independently of what the tissues hold.

Sources

  • Q10 - Coenzyme Q10, Reduced and Total, Plasma: Clinical & Interpretive — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult total CoQ10 reference values 433 to 1532 mcg/L (0.43 to 1.53 μg/mL), taken from Miles et al. 2004. Sera's sufficient lower edge of 1.0 μg/mL is more than double the lower limit.
  • Coenzyme Q10, Total — Labcorp, 2026 · Laboratory / reference-interval sourceReference range 0.37 to 2.20 μg/mL. Sera's sufficient lower edge of 1.0 sits in the middle of it.

Last reviewed: November 9, 2026 · CoQ10 on its own page

Vitamin B12 (Total)Functional / longevity targetpg/mL · pmol/L · ng/L

The standard vitamin B12 test, which counts both the usable and the unusable forms of a vitamin your body needs for healthy nerves and for making energy.

UnitOptimalSufficientOut of range
pg/mL500 – 900200 – 1,500below 200 or above 1,500
pmol/L369 – 664148 – 1,100below 148 or above 1,100
ng/L500 – 900200 – 1,500below 200 or above 1,500

Interpretation: Total B12 includes the fraction bound to haptocorrin, which is not available to cells. A result in the lower half with symptoms is worth following with methylmalonic acid or active B12. The acceptable lower edge of 200 pg/mL (148 pmol/L) is where most laboratories call a result low; NICE treats below 180 ng/L as confirmed deficiency and 180 to 350 as indeterminate. The optimal lower edge of 500 is above every published figure and is a functional target. The acceptable upper edge of 1500 has no source: the highest laboratory upper limit confirmed is 1245.

Sources

  • Vitamin B12 - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2025 · Government / public-health guidanceMost laboratories define subnormal serum B12 as below 200 or 250 pg/mL (148 or 185 pmol/L); MMA should be checked when B12 is 150 to 399 pg/mL. Matches Sera's sufficient lower edge of 200 pg/mL exactly. Updated July 2, 2025.
  • Vitamin B12 deficiency in over 16s: diagnosis and management (NG239), Recommendations, Table 1 — National Institute for Health and Care Excellence (NICE), 2024 · Clinical guidelineTotal B12 below 180 ng/L (133 pmol/L) is confirmed deficiency, 180 to 350 ng/L (133 to 258 pmol/L) is indeterminate, above 350 ng/L makes deficiency unlikely. Supports Sera's note that a lower-half result with symptoms needs follow-up; does not reach Sera's optimal lower edge of 500.
  • B12 - Vitamin B12 Assay, Serum: Clinical & Interpretive — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference values 180 to 914 ng/L; below 150 is evidence of deficiency and 150 to 400 is borderline, to be followed with methylmalonic acid or homocysteine. The upper limit of 914 is close to Sera's optimal upper edge of 900.
  • Vitamin B12 — Labcorp, 2026 · Laboratory / reference-interval sourceReference range 232 to 1245 pg/mL. The highest verified laboratory upper limit; Sera's sufficient upper edge of 1500 is above it.

Last reviewed: November 9, 2026 · Vitamin B12 on its own page

Vitamin B12 (Active - Holotranscobalamin)Established clinical thresholdAssay-dependentpmol/L

The part of your vitamin B12 that is carried by transcobalamin, which is the only form your cells can actually take up.

UnitOptimalSufficientOut of range
pmol/L70 – 16525 – 200below 25 or above 200

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The lower bands follow the NICE guideline on vitamin B12 deficiency (2024): below 25 pmol/L is confirmed deficiency, 25 to 70 is indeterminate and worth following with methylmalonic acid, and above 70 makes deficiency unlikely. Thresholds differ between assays, so a laboratory's own validated cut-offs take precedence. No upper limit is published for active B12. The upper edges here (165 and 200 pmol/L) are kept on purpose all the same: a total B12 result entered against this marker by mistake runs several times higher, and the upper edge is what catches it.

Sources

  • Vitamin B12 deficiency in over 16s: diagnosis and management (NG239), Recommendations, Table 1 — National Institute for Health and Care Excellence (NICE), 2024 · Clinical guidelineActive B12 below 25 pmol/L is confirmed deficiency, 25 to 70 pmol/L is indeterminate (possible deficiency), above 70 pmol/L suggests deficiency is unlikely. Matches Sera's sufficient lower edge of 25 and optimal lower edge of 70 exactly.
  • Active B12/HoloTC — North Bristol NHS Trust, Severn Pathology, 2026 · Laboratory / reference-interval sourceReference range in three bands: above 70 deficiency unlikely, 25 to 70 indeterminate, below 25 consistent with deficiency. The page prints the unit as pmol/mL, which appears to be a misprint for pmol/L. No upper limit is given.

Last reviewed: November 9, 2026 · Active B12 on its own page

Folate (Serum)Established clinical thresholdOne-sidedng/mL · nmol/L · μg/L

A B vitamin needed for cells to divide and for a process called methylation, measured in serum.

UnitOptimalSufficientOut of range
ng/mL10 – 203 – 30below 3
nmol/L23 – 457 – 68below 7
μg/L10 – 203 – 30below 3

Bounded on the low side only — a high result is not treated as out of range. The published thresholds define deficiency only; a high serum folate usually reflects supplements or fortified food.

Interpretation: The acceptable band starts at 3 ng/mL (about 7 nmol/L), the level below which WHO and NIH define folate deficiency; Mayo Clinic Laboratories uses 4. Laboratories publish no upper limit, so a high result is not flagged. The optimal band of 10 to 20 ng/mL has no published threshold behind it. Serum folate reflects recent intake, so one low result does not establish long-term status.

Sources

  • Folate - Health Professional Fact Sheet — NIH Office of Dietary Supplements, 2022 · Government / public-health guidanceA serum folate above 3 ng/mL indicates adequacy; the measure is sensitive to recent intake. Matches Sera's sufficient lower edge exactly. Updated November 30, 2022.
  • Folate (Folic Acid) — Labcorp, 2026 · Laboratory / reference-interval sourceReference range above 3.0 ng/mL, with no upper limit; below 3 ng/mL is clinical deficiency per the World Health Organization. Matches Sera's sufficient lower edge exactly.
  • FOL - Folate, Serum: Clinical & Interpretive — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference value 4.0 mcg/L or more, with no upper limit; below 4.0 suggests deficiency, a consensus cut-off derived from NHANES III. Close to Sera's sufficient lower edge of 3.

Last reviewed: November 9, 2026 · Serum folate on its own page

Folate (RBC)Established clinical thresholdOne-sidedng/mL · nmol/L · μg/L

Folate measured inside your red blood cells rather than in the liquid part of the blood. Red cells live about 120 days and take up folate only while they are being made, so this reflects your folate status over months.

UnitOptimalSufficientOut of range
ng/mL135 – 534—below 135
nmol/L305 – 1,210—below 305
μg/L135 – 534—below 135

No separate Sufficient band is currently defined for this marker.

Bounded on the low side only — a high result is not treated as out of range. No high-folate pathology and no evidence-based upper cut-off; 1 mg methylfolate routinely carries red cell folate above the plotted domain.

Interpretation: Red cell folate reflects folate status over the life of the red cell, roughly the previous three months. The band starts at 305 nmol/L (135 ng/mL), the deficiency cut-off for the microbiological assay used by the UK National Diet and Nutrition Survey. Immunoassays read on a different scale and some laboratories set their lower limit far higher (366 ng/mL at one large US laboratory), so read a result against the reporting laboratory's own interval first. For women who could become pregnant, population surveys use a separate, higher threshold of 748 nmol/L for neural tube defect risk; Sera does not score against it. A high result is not flagged: no laboratory or guideline defines an upper cut-off, and supplementation routinely carries red cell folate above the plotted range.

Sources

Last reviewed: November 9, 2026 · RBC folate on its own page

Vitamin B6Established clinical thresholdAssay-dependentnmol/L · μg/L

A B vitamin your body needs to process protein, make brain chemicals like serotonin, and build red blood cells. The blood test measures its active form, called pyridoxal 5'-phosphate (PLP).

UnitOptimalSufficientOut of range
nmol/L30 – 11020 – 150below 20 or above 150
μg/L7.5 – 275 – 37below 5 or above 37

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The test measures pyridoxal 5'-phosphate (PLP), the active form of vitamin B6, and should be taken fasting: a non-fasting sample reflects recent intake. The optimal band starts at 30 nmol/L, the plasma PLP level EFSA uses as its marker of adequate status. The acceptable band starts at 20 nmol/L, the lower limit of a large US laboratory's reference interval. The upper edges of 110 and 150 nmol/L have no published threshold behind them: laboratory upper limits range from 125 to about 264 nmol/L, and no source gives a PLP level at which harm begins.

Sources

  • Dietary Reference Values for vitamin B6 — EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) — EFSA Journal, 2016 · Government / public-health guidanceEFSA treats a plasma PLP concentration of 30 nmol/L as indicating adequate vitamin B6 status and sets European requirements from it. Still the EFSA opinion in force. Matches Sera's optimal lower edge of 30 nmol/L.
  • Vitamin B6: a scoping review for Nordic Nutrition Recommendations 2023 — Bjørke-Monsen AL, Ueland PM — Food & Nutrition Research, 2023 · Peer-reviewed publicationConfirms that 30 nmol/L PLP is the figure current intake recommendations rest on, and cautions that it may be too low as a marker of adequate status.
  • Vitamin B6 (Pyridoxal 5'-Phosphate) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP's fasting reference interval for PLP by mass spectrometry is 20 to 125 nmol/L. The lower limit is Sera's sufficient lower edge; the upper limit of 125 sits between Sera's 110 and 150.
  • Vitamin B6, Plasma — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp reports PLP with an interval of 3.4 to 65.2 µg/L: deficiency below 3.4, marginal 3.4 to 5.1, adequate above 5.1. The 5.1 figure matches Sera's sufficient lower edge of 5 µg/L; the upper limit comes from a Labcorp internal study and is far above Sera's 37.

Last reviewed: November 9, 2026 · Vitamin B6 on its own page

Zinc (Serum)Published reference intervalAssay-dependentμg/dL · μmol/L · mg/L

Serum zinc, the circulating fraction — distinct from the red cell compartment, which reflects a longer window.

UnitOptimalSufficientOut of range
μg/dL90 – 12070 – 150below 70 or above 150
μmol/L14 – 1811 – 23below 11 or above 23
mg/L0.9 – 1.20.7 – 1.5below 0.7 or above 1.5

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The acceptable band of 70 to 150 μg/dL (11 to 23 μmol/L) is close to one UK trace-element laboratory's interval of 11 to 24 μmol/L. Other laboratories run lower: ARUP 60 to 120 μg/dL and Labcorp 44 to 115. The optimal upper edge of 120 equals ARUP's upper limit; the optimal lower edge of 90 has no source. Serum zinc falls after meals and with inflammation.

Sources

  • Zinc (Plasma/Serum) — Black Country Pathology Services (Trace Elements Laboratory, Sandwell; NHS), 2026 · Laboratory / reference-interval sourceReference range for all ages 11 to 24 µmol/L; deficiency may be indicated below 7.0; above 24 suggests supplement use or contamination. Matches Sera's acceptable band of 11 to 23 µmol/L (70 to 150 µg/dL).
  • Zinc, Serum or Plasma — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP's interval is 60 to 120 µg/dL. The upper limit equals Sera's optimal upper edge; the lower limit is below Sera's 70. Notes that zinc falls with infection, inflammation, oral contraceptives and pregnancy.
  • Zinc, Plasma or Serum — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp's interval from 11 months of age is 44 to 115 µg/dL for both sexes, well below Sera's lower edge of 70. Zinc should be read with serum albumin.
  • Zinc, serum — Newcastle Hospitals NHS Foundation Trust — Newcastle Laboratories, 2026 · Laboratory / reference-interval sourceSex- and age-specific intervals by ICP-MS: 19 to 64 years, women 9.6 to 20.5 and men 10.1 to 20.2 µmol/L. Advises measuring two weeks after an acute phase response has resolved.
  • Serum Zinc Concentrations in the US Population Are Related to Sex, Age, and Time of Blood Draw but Not Dietary or Supplemental Zinc — Hennigar SR, Lieberman HR, Fulgoni VL, McClung JP — The Journal of Nutrition, 2018 · Peer-reviewed publicationUS population means are 84.9 µg/dL in men and 80.6 in women, both below Sera's optimal lower edge of 90. Afternoon and evening draws read about 10 to 15 µg/dL lower, and serum zinc did not track zinc intake.

Last reviewed: November 9, 2026 · Serum zinc on its own page

Zinc (RBC)Published reference intervalAssay-dependentμg/dL · μmol/L

Erythrocyte zinc, the intracellular fraction, which runs roughly an order of magnitude above serum.

UnitOptimalSufficientOut of range
μg/dL900 – 1,500—below 900 or above 1,500
μmol/L137.7 – 229.4—below 137.7 or above 229.4

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The reason to measure it: serum zinc falls during any acute-phase response independently of status, so a low serum zinc with a raised CRP says more about inflammation than about zinc. The red cell compartment reflects weeks to months and is far less disturbed. Intervals are markedly laboratory-specific: two large US laboratories publish 794 to 1470 µg/dL and, for adults over 40, 1005 to 1559 µg/dL, so a result between 794 and 1005 is low at one and normal at the other. Sera's band of 900 to 1500 sits between them; read the result against the reporting laboratory's own interval first. Some laboratories report per gram of haemoglobin rather than per volume — a different scale, not a different unit. No guideline defines a deficiency threshold for red cell zinc, and a sample that was haemolysed or slow to be separated can read falsely low.

Sources

  • Zinc, RBC — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP's red cell zinc interval is 794 to 1470 µg/dL. Its lower limit is about 100 µg/dL below Sera's 900 and its upper limit 30 below Sera's 1500.
  • Zinc, RBC — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp's intervals in µg/dL: 13 to 30 years 955 to 1513; 31 to 40 years 990 to 1529 (women) and 1007 to 1529 (men); 41 years and over 1005 to 1559. Both limits sit above Sera's.

Last reviewed: November 9, 2026 · RBC zinc on its own page

CopperPublished reference intervalSex-specificAssay-dependentμg/dL · μmol/L · mg/L

A trace mineral that helps you absorb iron, build connective tissue, and protect cells from damage.

UnitApplies toOptimalSufficientOut of range
μg/dLFemale80 – 12080 – 155below 80 or above 155
μg/dLMale80 – 12070 – 140below 70 or above 140
μmol/LFemale12.6 – 18.912.6 – 24.4below 12.6 or above 24.4
μmol/LMale12.6 – 18.911 – 22below 11 or above 22
mg/LFemale0.8 – 1.20.8 – 1.55below 0.8 or above 1.55
mg/LMale0.8 – 1.20.7 – 1.4below 0.7 or above 1.4

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The acceptable band follows a large US laboratory's adult reference interval: 70 to 140 µg/dL for men and 80 to 155 for women. Where the client's sex is not recorded, the men's figures are used. UK laboratories commonly report 11 to 25 µmol/L for all adults. Women run higher because oestrogen raises caeruloplasmin, the protein that carries copper: oral contraceptives, hormone therapy and pregnancy can lift serum copper well above the band, as can any inflammation, so read a high result beside CRP before treating it as copper excess. A low result is seen with high-dose zinc, malabsorption and corticosteroids. The optimal band of 80 to 120 µg/dL has no published threshold behind it.

Sources

  • Copper, Serum or Plasma — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceAdults 19 years and older: men 70 to 140 µg/dL, women 80 to 155 µg/dL. The male interval is Sera's current acceptable band; the female interval is the basis for the proposed female row.
  • Copper, Serum or Plasma — Labcorp, 2026 · Laboratory / reference-interval sourceOver 30 years: men 66 to 121, women 76 to 142 µg/dL; 16 to 30 years: men 62 to 115, women 73 to 140. Confirms that women's intervals run about 10 to 20 µg/dL higher than men's.
  • Copper (Plasma/Serum) — Black Country Pathology Services (Trace Elements Laboratory, Sandwell; NHS), 2026 · Laboratory / reference-interval sourceChildren over 12 months and adults: 11 to 25 µmol/L, with 25 to 39 in pregnancy beyond 15 weeks. The lower limit matches Sera's 11 µmol/L; the upper limit is 3 above Sera's 22.

Last reviewed: November 9, 2026 · Copper on its own page

Zinc:Copper Ratio (Serum)Exploratory indexAuto-calculated

Serum zinc divided by serum copper. The two minerals compete for absorption and move in opposite directions under inflammation, so the balance between them can say something neither says alone.

Auto-calculated

Serum Zinc (μg/dL) / Serum Copper (μg/dL)

Calculated when Zinc (Serum) and Copper are recorded in the same blood test, after normalizing the inputs to the units the formula expects.

UnitOptimalSufficientOut of range
ratio0.8 – 1.20.6 – 1.4below 0.6 or above 1.4

Interpretation: The band is derived from Sera's own constituents rather than taken from the literature. Sera bands serum zinc at 90-120 μg/dL and serum copper at 80-120, so a client at the centre of both computes to 1.05, and an optimal band that excluded 1.05 would have Sera calling two markers optimal and the ratio between them worse. 0.8-1.2 brackets that centre.

The 0.7-1.0 figure often cited in the literature is a copper:zinc ratio (Cu/Zn), not zinc:copper. Inverted, that corresponds to a Zn/Cu ratio of roughly 1.0-1.4, which overlaps Sera's sufficient band but not its optimal. The two are not interchangeable. Its provenance is also thinner than it looks: it traces to the Kuopio cohort, where the association attenuated to non-significance after adjustment (HR 1.21, 0.96-1.53) and serum copper alone outperformed the ratio. Hence the exploratory grade. Read the two constituents and CRP beside it, and treat a shifted ratio as a prompt to see which of the two moved.

A high ratio (above 1.2) often reflects low copper relative to zinc, most often high-dose zinc supplementation taken without copper. A low ratio (below 0.8) often reflects relative copper excess or zinc insufficiency, commonly seen in chronic inflammation.

Sources

No source is listed. This is a calculated index with no universally accepted clinical threshold to cite. The 0.8-1.2 band is derived from Sera's existing zinc and copper optimal ranges to ensure internal consistency, not from a published Zn/Cu ratio target.

Last reviewed: November 9, 2026

Copper (RBC)Published reference intervalAssay-dependentμg/dL · mg/L · μmol/L

Copper measured inside red blood cells rather than in serum.

UnitOptimalSufficientOut of range
μg/dL53 – 91—below 53 or above 91
mg/L0.53 – 0.91—below 0.53 or above 0.91
μmol/L8.3 – 14.3—below 8.3 or above 14.3

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The band is Quest's interval, 53 to 91 μg/dL (0.53 to 0.91 mg/L). NMS Labs, which runs the test for Mayo, agrees on the upper edge of 91 but starts at 59, so a result of 53 to 58 would be low there. The μmol/L row is a conversion: no UK or European laboratory interval was found, and the test is rarely ordered outside the US. No source supports a narrower optimal range. Read it with serum copper, ceruloplasmin and zinc.

Sources

  • Copper, RBC (test code 3481) — Quest Diagnostics, 2026 · Laboratory / reference-interval sourceRBC copper by ICP-MS: 0.53 to 0.91 mg/L (53 to 91 μg/dL). Both of Sera's edges.
  • Copper, RBCs (Test Code FCOPP) — NMS Labs (performing laboratory), Bronson Laboratory Services catalog, 2026 · Laboratory / reference-interval source2.5th to 97.5th percentiles 59 to 91 μg/dL (n = 1999). Confirms the upper edge; its lower edge is 59 rather than 53.

Last reviewed: November 9, 2026 · RBC copper on its own page

CeruloplasminPublished reference intervalSex-specificmg/dL · g/L

The protein that carries most of the copper in the blood, made by the liver.

UnitApplies toOptimalSufficientOut of range
mg/dLMale19 – 31—below 19 or above 31
mg/dLFemale20 – 51—below 20 or above 51
g/LMale0.19 – 0.31—below 0.19 or above 0.31
g/LFemale0.2 – 0.51—below 0.2 or above 0.51

No separate Sufficient band is currently defined for this marker.

Interpretation: The bands are Mayo Clinic Laboratories' adult intervals: 19 to 31 mg/dL for men and 20 to 51 mg/dL for women (0.19 to 0.31 and 0.20 to 0.51 g/L). Every source, Mayo and four NHS trusts, puts the low edge at about 0.20 g/L, and that is the edge that matters: North Bristol reads below 0.10 g/L as highly suggestive of Wilson disease. Upper edges differ with the assay and with oestrogen (UK laboratories print 0.45 to 0.6 g/L). Ceruloplasmin rises with inflammation, pregnancy and the contraceptive pill, so a high result is common and non-specific. No source supports a narrower optimal range.

Sources

  • Ceruloplasmin, Serum (CERS) — Mayo Clinic Laboratories (performing laboratory), Duke University Hospital test catalog, 2026 · Laboratory / reference-interval sourceAdult intervals by nephelometry: men 19.0 to 31.0 mg/dL, women 20.0 to 51.0 mg/dL. The basis of Sera's bands.
  • Caeruloplasmin, serum — Severn Pathology, North Bristol NHS Trust, 2026 · Laboratory / reference-interval source0.20 to 0.32 g/L makes Wilson disease highly unlikely, 0.10 to 0.19 does not exclude it, and below 0.10 is highly suggestive. Supports the 0.20 g/L low edge.
  • Caeruloplasmin — University Hospitals of North Midlands NHS Trust, Pathology, 2026 · Laboratory / reference-interval sourceUK intervals by sex: women 0.16 to 0.45 g/L, men 0.15 to 0.30 g/L. Confirms the sex split and the male upper edge.
  • Caeruloplasmin (test directory) — York and Scarborough Teaching Hospitals NHS Foundation Trust, Laboratory Medicine, 2026 · Laboratory / reference-interval source0.2 to 0.6 g/L for all adults, quoted from the Protein Reference Unit. The same 0.2 g/L low edge with a wider upper edge.
  • 216 Caeruloplasmin — University Hospitals Sussex NHS Foundation Trust, Pathology, 2025 · Laboratory / reference-interval sourceAdult interval 0.2 to 0.6 g/L. The same 0.2 g/L low edge.

Last reviewed: November 9, 2026 · Ceruloplasmin on its own page

Methylmalonic Acid (MMA)Published reference intervalAssay-dependentnmol/L · μg/L · ng/mL

A substance that builds up in the body when cells do not have enough usable vitamin B12. It is the most sensitive sign of true B12 status.

UnitOptimalSufficientOut of range
nmol/L0 – 271271 – 370below 0 or above 370
μg/L0 – 3232 – 43.7below 0 or above 43.7
ng/mL0 – 3232 – 43.7below 0 or above 43.7

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: MMA rises when vitamin B12 is too low for the cells to use, so it is read as a functional test of B12 status, most useful when serum B12 is borderline. The acceptable band ends at 370 nmol/L, the cut-off a large US laboratory describes as generally agreed for elevated MMA; in US survey data a result above about 376 was more than 99% specific for inadequate B12 status. The optimal band ends at 271 nmol/L, the cut-off US population studies have long used; a CDC analysis suggests 229 nmol/L when screening people at higher risk of deficiency. MMA also rises with age and with reduced kidney function independently of B12, so check eGFR before reading a raised result as B12 deficiency. A low result has no clinical meaning.

Sources

Last reviewed: November 9, 2026 · Methylmalonic acid (MMA) on its own page

Autoimmune · 28 markers

Antibodies used to investigate systemic, joint, and gut autoimmunity

Antinuclear Antibody (ANA) — ScreenEstablished clinical thresholdAssay-dependenttiter

The first-line screen for systemic autoimmunity, reported as the highest dilution at which staining is still visible on HEp-2 cells.

UnitOptimalSufficientOut of range
titer0 – 1:401:40 – 1:80below 0 or above 1:80

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: A screen, and its value is mostly in ruling out: a negative ANA makes lupus unlikely, while a positive one is common in people with no disease at all — roughly a quarter of healthy adults reach 1:80, more with age and more in women. The optimal band stops below 1:80, the titre the EULAR/ACR lupus criteria use as their entry point and the level below which ARUP and Labcorp report a negative. A result of 1:80 is borderline; above that, laboratories report a positive. Titre is the signal, so 1:320 and above carries weight that 1:80 does not, and the staining pattern tells you which follow-up antibody to order. Never read a positive ANA as a diagnosis on its own.

Sources

  • Performance of Antinuclear Antibodies for Classifying Systemic Lupus Erythematosus: A Systematic Literature Review and Meta-Regression of Diagnostic Data — Leuchten N, Hoyer A, Brinks R, et al. — Arthritis Care & Research, 2018 · Peer-reviewed publicationThe systematic review done for the EULAR/ACR criteria committee, covering 13,080 lupus patients. It concludes that an ANA of 1:80 is sensitive enough to be the entry criterion, which is why Sera's optimal band stops below 1:80. Specificity is modest at that titre and rises with each dilution.
  • Antinuclear Antibody (ANA) with HEp-2 Substrate, IgG by IFA with Reflex by Pattern — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP's reference interval for ANA by HEp-2 immunofluorescence is less than 1:80, so a 1:40 result is reported as within the interval. Matches Sera's optimal band.
  • ANA by IFA, Reflex to Titer and Pattern — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp reports below 1:80 as negative, 1:80 as borderline and above 1:80 as positive, and says titres of 1:160 or more usually go with active lupus. This supports an acceptable band of 1:80 only, not one that runs to 1:160.
  • EULAR/ACR Classification Criteria for Systemic Lupus Erythematosus — European League Against Rheumatism / American College of Rheumatology, 2019 · Professional societySets an ANA of 1:80 or above on HEp-2 cells as the entry criterion for classifying lupus — nothing further is scored below it. Sera's optimal band stops immediately below that dilution. The criteria classify rather than diagnose, and a positive ANA is common in people without disease.
  • Simplified Criteria for the Diagnosis of Autoimmune Hepatitis — International Autoimmune Hepatitis Group, 2008 · Professional societyScores ANA or ASMA at 1:40 as one point and at 1:80 or above as two, which is the split Sera's optimal and acceptable bands follow for ASMA. The criteria are a composite — antibodies, IgG, histology and viral exclusion together — so no antibody titre stands alone.

Last reviewed: November 9, 2026 · ANA on its own page

Anti-CCP (Cyclic Citrullinated Peptide)Published reference intervalAssay-dependentU/mL · AU/mL

An antibody against citrullinated proteins, and the most specific blood marker for rheumatoid arthritis.

UnitOptimalSufficientOut of range
U/mL0 – 2020 – 40below 0 or above 40
AU/mL0 – 2020 – 40below 0 or above 40

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The 20 U/mL edge is the cut-off the great majority of assays are calibrated to, not a guideline figure; on that scale laboratories such as ARUP report 20 to 39 as weak positive and 40 and above as moderate to strong positive, which is where the acceptable band ends. ACR/EULAR score this marker against the issuing laboratory's own upper limit, so read a borderline value against the interval on the report. Specificity for rheumatoid arthritis is high, around 95%, and antibodies can appear years before joint symptoms do.

Sources

  • Cyclic Citrullinated Peptide Antibody, IgG and IgA — ARUP Laboratories, 2026 · Laboratory / reference-interval source19 Units or less is negative, 20 to 39 weak positive, 40 to 59 moderate positive, 60 or greater strong positive. Sera's optimal band ends at the negative cut-off and its acceptable band at the end of weak positive.
  • Rheumatoid Arthritis Classification Criteria — American College of Rheumatology / European League Against Rheumatism, 2010 · Professional societyScores anti-CCP and rheumatoid factor against the issuing assay's own upper limit of normal, separating low-positive (up to three times that limit) from high-positive. Sera's optimal/acceptable split mirrors that tiering; the criteria set no absolute cut-off in U/mL, which is why the marker is flagged assay-dependent.

Last reviewed: November 9, 2026 · Anti-CCP on its own page

Rheumatoid Factor (RF)No universal rangeUnbandedIU/mL · U/mL · unbanded

An antibody directed against the body's own immunoglobulin, historically the first blood test for rheumatoid arthritis.

No universal Sera range published.

Positive in Sjögren's, chronic infection and healthy older adults, and cut-offs differ by assay. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is published. Laboratories set their own cut-off; ARUP and Labcorp both use about 14 IU/mL, but other assays differ, and ACR/EULAR score RF against the issuing laboratory's upper limit. Read the result against the interval on the report. RF is also positive in Sjögren's, lupus, chronic infections such as hepatitis C, and in some healthy people, more often with age.

Sources

  • Rheumatoid Factor — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP's reference interval for rheumatoid factor is 0 to 14 IU/mL.
  • Rheumatoid Factor (RF) — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp's reference interval is below 14.0 IU/mL, the same cut-off as ARUP.
  • Rheumatoid Factor (RF) Test — MedlinePlus, US National Library of Medicine, 2025 · Government / public-health guidanceGives no numeric cut-off. States that healthy people can carry RF and that it is also raised in Sjögren's, lupus, scleroderma, hepatitis C, tuberculosis, endocarditis and some cancers.

Last reviewed: November 9, 2026

Anti-dsDNA (Double-Stranded DNA)No universal rangeUnbandedIU/mL · U/mL · unbanded

An antibody against double-stranded DNA, highly specific for systemic lupus erythematosus.

No universal Sera range published.

Farr, ELISA and immunofluorescence assays report on scales that are not interchangeable. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is published. Cut-offs depend on the method: ARUP's ELISA reports 24 IU or less as negative, while Labcorp's assay reports above 9 IU/mL as positive. Read the result against the interval on the report, and compare a client's results over time only when they come from the same laboratory.

Sources

Last reviewed: November 9, 2026

Anti-SSA (Ro)No universal rangeUnbandedU/mL · AU/mL · unbanded

An extractable nuclear antigen antibody, most associated with Sjögren's syndrome and lupus.

No universal Sera range published.

Extractable nuclear antigen assays are not standardised between platforms. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is published. Anti-SSA is reported in arbitrary units that differ by platform: ARUP's reference interval is 40 AU/mL or less, Labcorp's is 0.0 to 0.9 AI. Read the result as negative, equivocal or positive against the interval on the report.

Sources

Last reviewed: November 9, 2026

Anti-SSB (La)No universal rangeUnbandedU/mL · AU/mL · unbanded

An extractable nuclear antigen antibody, usually found alongside anti-SSA in Sjögren's syndrome.

No universal Sera range published.

Extractable nuclear antigen assays are not standardised between platforms. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is published. Anti-SSB is reported in arbitrary units that differ by platform: ARUP's reference interval is 40 AU/mL or less, Labcorp's is 0.0 to 0.9 AI. Read the result as negative, equivocal or positive against the interval on the report.

Sources

Last reviewed: November 9, 2026

Anti-Sm (Smith)No universal rangeUnbandedU/mL · AU/mL · unbanded

An extractable nuclear antigen antibody that is close to diagnostic for systemic lupus erythematosus.

No universal Sera range published.

Extractable nuclear antigen assays are not standardised between platforms. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is published. Anti-Sm is reported in arbitrary units that differ by platform: ARUP's reference interval is 40 AU/mL or less, while laboratories using a multiplex antibody index report 1.0 AI or less. Read the result as negative, equivocal or positive against the interval on the report.

Sources

  • Extractable Nuclear Antigen Antibodies (Smith/RNP, Smith, SSA 52, SSA 60, and SSB) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP reports anti-Sm (Smith) in AU/mL: 29 or less negative, 30 to 40 equivocal, 41 or greater positive, with a reference interval of 40 AU/mL or less. The scale is ARUP's own.
  • Smith Antibody — University of Iowa Health Care, Department of Pathology Laboratory Services Handbook, 2013 · Laboratory / reference-interval sourceA US hospital laboratory's multiplex flow immunoassay reports an antibody index with a reference range of 1.0 AI or less. The range dates from February 2013 and is the one on the current handbook page.

Last reviewed: November 9, 2026

Anti-RNP (Ribonucleoprotein)No universal rangeUnbandedU/mL · AU/mL · unbanded

An extractable nuclear antigen antibody found in mixed connective tissue disease and in lupus.

No universal Sera range published.

Extractable nuclear antigen assays are not standardised between platforms. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is published. Anti-RNP is reported in arbitrary units that differ by platform: ARUP's reference interval is 40 AU/mL or less, while laboratories using a multiplex antibody index report 1.0 AI or less. Read the result as negative, equivocal or positive against the interval on the report.

Sources

  • Extractable Nuclear Antigen Antibodies (Smith/RNP, Smith, SSA 52, SSA 60, and SSB) — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP reports anti-Sm/RNP in AU/mL: 29 or less negative, 30 to 40 equivocal, 41 or greater positive, with a reference interval of 40 AU/mL or less. The scale is ARUP's own.
  • Sm/RNP (Common Motif) Antibodies — University of Iowa Health Care, Department of Pathology Laboratory Services Handbook, 2013 · Laboratory / reference-interval sourceA US hospital laboratory's multiplex flow immunoassay reports an antibody index with a reference range of 1.0 AI or less. The range dates from February 2013 and is the one on the current handbook page.

Last reviewed: November 9, 2026

Anti-Scl-70 (Topoisomerase I)No universal rangeUnbandedU/mL · AU/mL · unbanded

An extractable nuclear antigen antibody associated with diffuse systemic sclerosis.

No universal Sera range published.

Extractable nuclear antigen assays are not standardised between platforms. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is published. Anti-Scl-70 is reported in arbitrary units that differ by platform: ARUP's reference interval is 40 AU/mL or less, Labcorp's is 0.0 to 0.9 AI. Read the result against the interval on the report. A low positive can be false, particularly when anti-dsDNA is also positive, and a negative does not rule out systemic sclerosis.

Sources

  • Scleroderma (Scl-70) (ENA) Antibody, IgG — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP: 29 AU/mL or less negative, 30 to 40 equivocal, 41 or greater positive. Notes that the antibody is found in about 20 percent of systemic sclerosis patients and that a negative does not exclude the disease.
  • Antiscleroderma − 70 Antibodies — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp's multiplex flow immunoassay reports an antibody index with a reference interval of 0.0 to 0.9 AI, a different scale from ARUP's AU/mL.

Last reviewed: November 9, 2026

Anti-CentromereNo universal rangeUnbandedU/mL · AU/mL · unbanded

An antibody against centromere proteins, associated with limited cutaneous systemic sclerosis.

No universal Sera range published.

Extractable nuclear antigen assays are not standardised between platforms. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is shown because laboratories report this antibody in their own arbitrary units: Labcorp calls 0.0 to 0.9 AI negative, ARUP calls 40 AU/mL or less negative. Read the result against the negative or positive call printed on the report.

Sources

  • Anticentromere B Antibodies — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp's multiplex flow immunoassay reports an antibody index; the reference interval is 0.0 to 0.9 AI. Shows the cut-off is specific to the assay's own unit.
  • Centromere Antibody, IgG — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP's multiplex bead assay reports in AU/mL; the reference interval is 40 AU/mL or less. A different unit and cut-off from Labcorp for the same antibody.

Last reviewed: November 9, 2026

Anti-Jo-1 (Histidyl-tRNA Synthetase)No universal rangeUnbandedU/mL · AU/mL · unbanded

An antibody associated with the antisynthetase syndrome and inflammatory myositis.

No universal Sera range published.

Extractable nuclear antigen assays are not standardised between platforms. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is shown because laboratories report this antibody in their own arbitrary units: Mayo calls below 1.0 U negative, Labcorp 0.0 to 0.9 AI, ARUP 40 AU/mL or less. Read the result against the negative or positive call printed on the report.

Sources

  • Jo 1 Antibodies, IgG, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceMayo reports in units: below 1.0 U is negative, 1.0 U or more is positive, at all ages.
  • Anti-Jo-1 — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp's multiplex flow immunoassay reports an antibody index; the reference interval is 0.0 to 0.9 AI.
  • Jo-1 Antibody, IgG — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceARUP's multiplex bead assay reports in AU/mL; the reference interval is 40 AU/mL or less.

Last reviewed: November 9, 2026

tTG IgA (Tissue Transglutaminase IgA)Published reference intervalAssay-dependentU/mL

The primary blood screen for coeliac disease, measuring IgA antibodies against tissue transglutaminase.

UnitOptimalSufficientOut of range
U/mL0 – 44 – 10below 0 or above 10

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Two things invalidate this result rather than change it: a low total IgA, which makes a negative meaningless, and a gluten-free diet already underway, which lowers the antibody in someone with untreated disease. The bands follow the Mayo Clinic Laboratories reference values: below 4 U/mL negative, 4 to 10 weak positive, above 10 positive. A result in the 4 to 10 band is a weak positive or equivocal result to follow up, not a reassuring one. Negative cut-offs vary between assays (some call anything below 7 U/mL negative), so the cut-off printed on the report takes precedence; guidelines express their thresholds as multiples of the assay's upper limit of normal for the same reason.

Sources

  • Tissue Transglutaminase Antibody, IgA, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceBelow 4.0 U/mL is negative, 4.0 to 10.0 U/mL weak positive, above 10.0 U/mL positive, at all ages. These are Sera's optimal upper edge of 4 and sufficient upper edge of 10.
  • Tissue Transglutaminase (tTG), IgA — Labcorp, 2026 · Laboratory / reference-interval sourceLabcorp's page carries two schemes: 0 to 3 negative, 4 to 10 weak positive, above 10 positive; and below 7.0 negative, 7.0 to 10.0 equivocal, above 10.0 positive. Both end at 10 U/mL, but the negative cut-off differs with the assay.
  • European Society Paediatric Gastroenterology, Hepatology and Nutrition Guidelines for Diagnosing Coeliac Disease 2020 — Husby S, Koletzko S, Korponay-Szabó I, et al. — Journal of Pediatric Gastroenterology and Nutrition, 2020 · Clinical guidelineA paediatric guideline, cited only for how thresholds are expressed: as a multiple of the assay's upper limit of normal (10 times) rather than a fixed U/mL figure, and total IgA must be measured alongside.
  • American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease — Rubio-Tapia A, Hill ID, Semrad C, et al. — American Journal of Gastroenterology (American College of Gastroenterology), 2023 · Clinical guidelineEstablishes tTG IgA as the first-line serologic test, requires total IgA to be measured alongside it because selective IgA deficiency invalidates a negative result, and requires the patient to be eating gluten. It does not set a numeric cut-off — that belongs to the assay.

Last reviewed: November 9, 2026 · tTG IgA on its own page

tTG IgG (Tissue Transglutaminase IgG)No universal rangeUnbandedU/mL · unbanded

The IgG version of the coeliac transglutaminase antibody, used when IgA is deficient.

No universal Sera range published.

No cross-platform cut-off; the IgG assays are calibrated independently of the IgA ones. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is shown because the negative cut-off depends on the assay (below 6 U/mL at Mayo, below 7 U/mL on another common platform) and the IgG scale is not interchangeable with the IgA one. The IgG test matters mainly when total IgA is low or undetectable. Read the result against the cut-off printed on the report.

Sources

Last reviewed: November 9, 2026

EMA IgA (Endomysial Antibody IgA)Published reference intervalAssay-dependenttiter

An IgA antibody against the endomysium, the connective tissue around muscle fibres, read by immunofluorescence. It detects the same target as tTG IgA by a different and more specific method.

UnitOptimalSufficientOut of range
titer0 – 1:5—below 0 or above 1:5

No separate Sufficient band is currently defined for this marker.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Endomysial antibody IgA is read by immunofluorescence and reported as negative or as a titre. The negative cut-off is set by each laboratory: some report negative below 1:5, others below 1:10 (ARUP), and some print only 'Negative'. Sera flags any titre from 1:5 upward; read the result against the cut-off printed on the report. Guidelines use EMA IgA as the second test, to confirm a positive or weakly positive tTG IgA, not as a stand-alone screen. The result is not valid in IgA deficiency, where an IgG-based test is used instead, and a negative result does not exclude coeliac disease, including in someone already on a gluten-free diet. No guideline sets a titre threshold, and the height of the titre has no agreed meaning.

Sources

  • Endomysial Antibody, IgA by IFA — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceSemi-quantitative indirect fluorescent antibody test with a reference interval of less than 1:10. This is one dilution step higher than Sera's proposed cut-off of 1:5; a laboratory using this interval does not report a titre of 1:5.
  • EMAT - Overview: Endomysial Antibodies, IgA, Titer, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference value is 'Negative' with no numeric titre; the titre is run only when the screen is positive or indeterminate. A negative result does not exclude coeliac disease or dermatitis herpetiformis.
  • Anti Endomysial, IgA (by IFA) — University of Washington Department of Laboratory Medicine and Pathology, 2026 · Laboratory / reference-interval sourceReference range is 'Negative', by indirect immunofluorescence on monkey oesophagus. The laboratory states the test cannot be used in IgA deficiency.
  • Coeliac disease: recognition, assessment and management (NG20), Recommendations — National Institute for Health and Care Excellence (NICE), 2015 · Clinical guidelinePublished 2 September 2015 and still the NICE guideline in force. Total IgA and IgA tTG are the first-choice tests; IgA EMA is used when IgA tTG is weakly positive; IgG EMA, IgG DGP or IgG tTG are considered if IgA is deficient. No titre cut-off is given.
  • European Society Paediatric Gastroenterology, Hepatology and Nutrition Guidelines for Diagnosing Coeliac Disease 2020 — Husby S, Koletzko S, Korponay-Szabó I, et al. — Journal of Pediatric Gastroenterology and Nutrition, 2020 · Clinical guidelinePaediatric guideline: initial testing is total IgA plus tTG IgA; an IgG-based test only if total IgA is low or undetectable. A no-biopsy diagnosis needs tTG IgA at 10 times the upper limit or more and a positive EMA IgA in a second blood sample. No EMA titre cut-off is given.

Last reviewed: November 9, 2026 · EMA IgA on its own page

DGP IgA (Deamidated Gliadin Peptide IgA)No universal rangeUnbandedU/mL · unbanded

An antibody against deamidated gliadin peptides, a complementary coeliac marker.

No universal Sera range published.

Manufacturer-specific units with no standardised cut-off across assays. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is shown because laboratories report this antibody in their own units: Mayo calls below 20 U negative, ARUP below 5 FLU. Read the result against the cut-off printed on the report. DGP antibodies are not recommended as the first test for coeliac disease; tTG IgA with total IgA is.

Sources

Last reviewed: November 9, 2026

DGP IgG (Deamidated Gliadin Peptide IgG)No universal rangeUnbandedU/mL · unbanded

The IgG version of the deamidated gliadin peptide antibody.

No universal Sera range published.

Manufacturer-specific units with no standardised cut-off across assays. Read this marker against the interval printed by the issuing laboratory.

Interpretation: No band is shown because laboratories report this antibody in their own units: Mayo calls below 20 U negative, ARUP below 5 FLU. Read the result against the cut-off printed on the report. DGP antibodies are not recommended as the first test for coeliac disease; tTG IgA with total IgA is.

Sources

Last reviewed: November 9, 2026

Total IgA (Immunoglobulin A)Published reference intervalmg/dL · g/L

The total amount of immunoglobulin A in the blood, measured to check whether IgA-based coeliac tests can be trusted.

UnitOptimalSufficientOut of range
mg/dL70 – 35661 – 356below 61 or above 356
g/L0.7 – 3.560.61 – 3.56below 0.61 or above 3.56

Interpretation: Measured to qualify the coeliac panel rather than for its own sake. Selective IgA deficiency affects roughly 1 in 500 people and is several times more common in coeliac disease, so the low edge is the one that matters here. The band is the Mayo Clinic Laboratories adult reference interval, 61 to 356 mg/dL (0.61 to 3.56 g/L); other laboratories set their lower limit anywhere from 61 to 90 mg/dL, so the interval on the report takes precedence. Selective IgA deficiency is defined much lower, as below 7 mg/dL (0.07 g/L) with normal IgG and IgM. A result between 7 mg/dL and the lower limit is a partial deficiency: it still weakens a negative tTG IgA. The narrower optimal band is a functional target; no published evidence supports it.

Sources

  • Immunoglobulin A (IgA), Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult reference interval, 18 years and over: 61 to 356 mg/dL. This is the proposed sufficient band (0.61 to 3.56 g/L).
  • Immunoglobulin A, Quantitative — Labcorp, 2026 · Laboratory / reference-interval sourceAdult intervals by sex and age: men 16 to 60 years 90 to 386 mg/dL, men over 60 61 to 437; women 16 to 70 years 87 to 352, women over 70 64 to 422. Shows that lower limits run from 61 to 90 and that no adult row reaches down to 50 or up to 450.
  • Selective IgA Deficiency and Allergy: A Fresh Look to an Old Story — Cinicola BL, Pulvirenti F, Capponi M, et al. — Medicina (Kaunas), 2022 · Peer-reviewed publicationItalian review giving the standard definition of selective IgA deficiency: IgA below 7 mg/dL with normal IgG and IgM in someone older than 4 years. This is far below the reference interval's lower limit and is the level at which IgA-based coeliac serology cannot be relied on.
  • American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease — Rubio-Tapia A, Hill ID, Semrad C, et al. — American Journal of Gastroenterology (American College of Gastroenterology), 2023 · Clinical guidelineEstablishes tTG IgA as the first-line serologic test, requires total IgA to be measured alongside it because selective IgA deficiency invalidates a negative result, and requires the patient to be eating gluten. It does not set a numeric cut-off — that belongs to the assay.

Last reviewed: November 9, 2026 · Total IgA on its own page

Complement C3Published reference intervalmg/dL · g/L

The central protein of the complement cascade, consumed when immune complexes activate it.

UnitOptimalSufficientOut of range
mg/dL90 – 17575 – 175below 75 or above 175
g/L0.9 – 1.750.75 – 1.75below 0.75 or above 1.75

Interpretation: Read for what it falls to. A low C3 with a low C4 means complement is being consumed, which in lupus tracks disease activity and renal involvement. C3 is also an acute-phase reactant, so concurrent inflammation can lift it and mask consumption, which is the reason the pair is always ordered together. The band is the Mayo Clinic Laboratories reference interval, 75 to 175 mg/dL (0.75 to 1.75 g/L). Laboratory intervals differ, with lower limits from 65 to 90 mg/dL and upper limits from 167 to 190, so the interval printed on the report takes precedence. The narrower optimal band is a functional target; no published evidence supports it.

Sources

  • Complement C3, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference interval 75 to 175 mg/dL; a fall into the abnormal range is consistent with disease activation in lupus. This is the proposed sufficient band (0.75 to 1.75 g/L).
  • Complement C3 — Labcorp, 2026 · Laboratory / reference-interval sourceReference interval 82 to 167 mg/dL for men and women beyond the first month of life. Close to Sera's current lower edge of 80, and well short of 200 at the top.
  • Complement (C3, C4 Levels) — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceUK laboratory interval for C3 of 0.90 to 1.80 g/L (updated January 2026). This equals Sera's current optimal band of 90 to 180 mg/dL, showing that band is a reference interval and not a tighter target.

Last reviewed: November 9, 2026 · Complement C3 on its own page

Complement C4Published reference intervalmg/dL · g/L

An early component of the classical complement pathway, ordered alongside C3.

UnitOptimalSufficientOut of range
mg/dL15 – 4010 – 40below 10 or above 40
g/L0.15 – 0.40.1 – 0.4below 0.1 or above 0.4

Interpretation: Falls earlier than C3 in classical-pathway activation, so an isolated low C4 points at lupus, cryoglobulinaemia or hereditary angioedema. Partial C4 gene deletions are common, giving a persistently low level in a healthy person, so a stable low C4 is not necessarily disease. The band, 10 to 40 mg/dL (0.10 to 0.40 g/L), is a UK NHS laboratory reference interval; Mayo and Labcorp set the lower limit at 14 and 12 mg/dL, so a result of 10 to 13 may be printed as low on the report, and the report's interval takes precedence. The narrower optimal band is a functional target; no published evidence supports it.

Sources

  • Complement (C3, C4 Levels) — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceUK laboratory interval for C4 of 0.10 to 0.40 g/L (updated January 2026): Sera's sufficient lower edge of 10 mg/dL and the proposed upper edge of 40. The page adds that a very low C4 in isolation can go with C1 inhibitor deficiency.
  • Complement C4, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceReference interval 14 to 40 mg/dL. Confirms 40 as the upper limit and shows a stricter lower limit of 14. An undetectable C4 with a normal C3 suggests congenital C4 deficiency.
  • Complement C4, Serum — Labcorp, 2026 · Laboratory / reference-interval sourceReference interval over 17 years: 12 to 38 mg/dL for men and women. A third lower limit (12) between 10 and 14, and an upper limit below 45.

Last reviewed: November 9, 2026 · Complement C4 on its own page

Immunoglobulin G (IgG)Published reference intervalmg/dL · g/L

The most abundant antibody class in the blood, and the measure of long-term humoral immunity.

UnitOptimalSufficientOut of range
mg/dL700 – 1,600600 – 1,600below 600 or above 1,600
g/L7 – 166 – 16below 6 or above 16

Interpretation: The total across all four subclasses, and a different test from any antigen-specific IgG on a coeliac or thyroid panel. A high level with raised transaminases supports autoimmune hepatitis; a low one is the finding that makes recurrent infection worth investigating. A normal total can hide a subclass deficiency. The bands are adult laboratory reference intervals, not outcome targets: NHS laboratories report 6 to 16 g/L or 7 to 16 g/L, and US laboratories about 600 to 1630 mg/dL. Use the interval printed on the report where it differs.

Sources

  • Immunoglobulins — Oxford University Hospitals NHS Foundation Trust, Immunology Laboratory, 2026 · Laboratory / reference-interval sourceAdult reference ranges: IgG 6.0 to 16.0 g/L, IgA 0.8 to 3.0 g/L, IgM 0.4 to 2.5 g/L. Matches Sera's sufficient lower edge of 6 g/L and puts the upper limit at 16, not 18. Page last reviewed 1 July 2026.
  • Immunoglobulins and Electrophoresis — Gloucestershire Hospitals NHS Foundation Trust, Pathology, 2025 · Laboratory / reference-interval sourceAdult (16 to 60 years) ranges: IgG 7.00 to 16.00 g/L, IgA 0.70 to 4.00 g/L, IgM 0.40 to 2.30 g/L. The IgG interval is Sera's optimal band of 7 to 16 g/L. Page updated September 2025.
  • Immunoglobulin G, Quantitative — Labcorp, 2026 · Laboratory / reference-interval sourceAdult (over 19 years) IgG reference interval: 603 to 1613 mg/dL in men, 586 to 1602 mg/dL in women. Matches Sera's sufficient lower edge of 600 mg/dL and an upper limit of about 1600, not 1800. Test directory page as opened in October 2026; it carries no publication date.

Last reviewed: November 9, 2026 · IgG on its own page

Immunoglobulin M (IgM)Published reference intervalmg/dL · g/L

The first antibody class produced in a new immune response, and the largest of them.

UnitOptimalSufficientOut of range
mg/dL50 – 20040 – 230below 40 or above 230
g/L0.5 – 20.4 – 2.3below 0.4 or above 2.3

Interpretation: Points at a recent rather than an established response. A markedly high IgM with a low IgG suggests a class-switching defect, and a persistently raised IgM in an older adult warrants a paraprotein screen. The bands are adult laboratory reference intervals: 0.4 to 2.3 g/L is the interval used by several NHS laboratories, and 0.5 to 2 g/L is a narrower one used by others. Some laboratories run wider, up to 2.5 g/L or 263 mg/dL, so use the interval printed on the report where it differs.

Sources

  • Immunoglobulins and Electrophoresis — Gloucestershire Hospitals NHS Foundation Trust, Pathology, 2025 · Laboratory / reference-interval sourceAdult (16 to 60 years) IgM range 0.40 to 2.30 g/L, the same as Sera's sufficient band. Page updated September 2025.
  • Immunoglobulins — York and Scarborough Teaching Hospitals NHS Foundation Trust, Laboratory Medicine, 2026 · Laboratory / reference-interval sourceIgM 0.5 to 1.9 g/L from 6 to 45 years and 0.5 to 2.0 g/L over 45; adult IgG 6 to 16 g/L. The over-45 IgM interval is Sera's optimal band. Test directory page as opened in October 2026; it carries no date.
  • Immunoglobulins (IgA, IgG, IgM), Quantitative — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceReference intervals at 19 years and older: IgG 768 to 1632 mg/dL, IgA 68 to 408, IgM 35 to 263. The IgM interval is a little wider than Sera's 40 to 230 mg/dL on both sides. Test directory page as opened in October 2026.

Last reviewed: November 9, 2026 · IgM on its own page

Immunoglobulin E (IgE)Published reference intervalIU/mL · kU/L

The antibody class behind immediate allergic reactions and the response to parasites.

UnitOptimalSufficientOut of range
IU/mL0 – 100100 – 214below 0 or above 214
kU/L0 – 100100 – 214below 0 or above 214

Interpretation: Says whether the immune system is skewed toward allergy, not what someone reacts to — that needs specific IgE. Higher in atopic eczema, asthma and parasitic infection, and markedly raised in allergic bronchopulmonary aspergillosis. A normal total does not exclude a specific allergy. Adult upper limits vary a great deal by laboratory: NHS laboratories use about 81 to 120 kU/L, ARUP uses 214 kU/L and Labcorp 495 IU/mL. The acceptable band ends at ARUP's 214; the optimal edge of 100 sits between the two UK limits and has no published threshold of its own. kU/L and IU/mL are the same number.

Sources

  • Immunoglobulin E — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceTotal serum IgE reference interval at 18 years and older: 214 kU/L or less. This is the nearest published limit to Sera's sufficient upper edge of 200. Test directory page as opened in October 2026.
  • Total IgE — Oxford University Hospitals NHS Foundation Trust, Immunology Laboratory, 2026 · Laboratory / reference-interval sourceAdult normal range for total IgE: 5 to 120 kU/L. The nearest UK limit above Sera's optimal upper edge of 100. Page last reviewed 6 July 2026.
  • Total IgE — York and Scarborough Teaching Hospitals NHS Foundation Trust, Laboratory Medicine, 2026 · Laboratory / reference-interval sourceAdult total IgE below 81 kU/L, quoted from the Protein Reference Unit; below 75 from 15 years to adult. The nearest UK limit below Sera's optimal upper edge of 100. Test directory page as opened in October 2026; it carries no date.

Last reviewed: November 9, 2026 · IgE on its own page

IA-2 Antibodies (Islet Antigen-2)Published reference intervalAssay-dependentU/mL · IU/mL

An antibody against a tyrosine phosphatase in the pancreatic beta cell, and one of the standard autoimmune diabetes markers.

UnitOptimalSufficientOut of range
U/mL0 – 1010 – 20below 0 or above 20
IU/mL0 – 1010 – 20below 0 or above 20

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Read as part of a panel, not alone: the ADA classification rests on how many islet autoantibodies are positive, and two or more makes autoimmune diabetes very likely. IA-2 is more closely tied to rapid progression than GAD65 and more often positive in children, but fades faster after diagnosis. Cut-offs are kit-specific, and the two laboratories checked (one US, one UK) both report IA-2 positive from 7.5 U/mL with no borderline zone. Sera's edges of 10 and 20 match neither, so a result between 7.5 and 20 reads Optimal or Sufficient here and may be positive on the report. Read it against the laboratory's own cut-off.

Sources

  • Islet Antigen-2 (IA-2) Autoantibody, Serum — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceReference interval 0.0 to 7.4 Units/mL by quantitative ELISA; 7.5 Units/mL or more is positive. Sera's U/mL bands put the first edge at 10 and the second at 20, neither of which this supports. Test directory page as opened in October 2026.
  • Islet Cell Antibody Panel (ICAP includes GAD, IA2 & ZT8) — Gloucestershire Hospitals NHS Foundation Trust, Pathology, 2025 · Laboratory / reference-interval sourcePositive cut-offs on the UK panel: GAD 11 U/mL or more, IA-2 7.5 U/mL or more, ZnT8 10 U/mL or more from age 30 and 65 U/mL or more under 30. The IA-2 cut-off is the same 7.5 U/mL as ARUP's. Page updated January 2025.

Last reviewed: November 9, 2026

ZnT8 Antibodies (Zinc Transporter 8)Published reference intervalAssay-dependentU/mL · IU/mL

An antibody against the zinc transporter in beta-cell secretory granules, the most recently adopted of the islet autoantibodies.

UnitOptimalSufficientOut of range
U/mL0 – 1515 – 20below 0 or above 20
IU/mL0 – 1515 – 20below 0 or above 20

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Its value is what it adds — positive in a portion of people negative for GAD65 and IA-2, converting some apparently antibody-negative cases into confirmed autoimmune diabetes. Rarely informative on its own. Cut-offs are kit-specific. ARUP reports anything above 15 U/mL as positive, which is the optimal upper edge here; nothing published supports a 15 to 20 middle zone, so a result in it reads Sufficient here and is positive on that assay. A UK panel uses different, age-split cut-offs. Read it against the laboratory's own cut-off.

Sources

  • Zinc Transporter 8 Antibody — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceReference interval 0.0 to 15.0 Kronus Units/mL; above 15.0 is positive. Matches Sera's optimal upper edge of 15 and leaves no room for a sufficient band from 15 to 20. Test directory page as opened in October 2026.
  • Islet Cell Antibody Panel (ICAP includes GAD, IA2 & ZT8) — Gloucestershire Hospitals NHS Foundation Trust, Pathology, 2025 · Laboratory / reference-interval sourceUK panel cut-offs for ZnT8 are split by age: positive at 10 U/mL or more from age 30, and at 65 U/mL or more under 30. Shows the cut-off is assay- and age-specific and can sit below Sera's 15. Page updated January 2025.

Last reviewed: November 9, 2026

GAD65 Antibodies (Glutamic Acid Decarboxylase 65)Published reference intervalAssay-dependentU/mL · IU/mL

An antibody against the enzyme glutamic acid decarboxylase in pancreatic beta cells, and the most durable marker of autoimmune diabetes.

UnitOptimalSufficientOut of range
U/mL0 – 1010 – 20below 0 or above 20
IU/mL0 – 55 – 10below 0 or above 10

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: The marker that separates autoimmune diabetes from type 2 in an adult with hyperglycaemia, which changes treatment rather than just the label. It persists for years after onset, unlike the insulin and islet-cell antibodies. The U/mL and IU/mL rows are separate standardisations with genuinely different cut-offs — copy the unit the report prints and never convert between them. Cut-offs are kit-specific. In IU/mL, ARUP reports anything above 5 as positive, which is the optimal upper edge here. In U/mL laboratories use 5 or 11 depending on the kit, and Sera's edges of 10 and 20 match neither exactly, so a result of 5 to 10 U/mL reads Optimal here and may be positive on the report. Read it against the laboratory's own cut-off.

Sources

  • Glutamic Acid Decarboxylase Antibody — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceReference interval 0.0 to 5.0 IU/mL; above 5.0 is positive. Matches Sera's optimal upper edge of 5 IU/mL and leaves no support for a sufficient band from 5 to 10. Test directory page as opened in October 2026.
  • GAD antibodies — Oxford University Hospitals NHS Foundation Trust, Immunology Laboratory, 2026 · Laboratory / reference-interval sourceNegative 0 to 4.9 U/mL; low positive 5 to 30 U/mL. Puts the lowest U/mL cut-off at 5, below Sera's optimal upper edge of 10. Labcorp's GAD-65 ELISA reference interval is likewise below 5 U/mL. Page last reviewed 1 July 2026.
  • Islet Cell Antibody Panel (ICAP includes GAD, IA2 & ZT8) — Gloucestershire Hospitals NHS Foundation Trust, Pathology, 2025 · Laboratory / reference-interval sourceGAD is positive at 11 U/mL or more on this NHS panel. This is the highest U/mL cut-off found, close to Sera's optimal upper edge of 10 and well below its sufficient upper edge of 20. Page updated January 2025.

Last reviewed: November 9, 2026

Anti-Mitochondrial Antibody (AMA)Established clinical thresholdAssay-dependenttiter · U/mL

An antibody against mitochondrial antigens, overwhelmingly the M2 subtype, and the defining serological marker of primary biliary cholangitis.

UnitOptimalSufficientOut of range
titer0 – 1:201:20 – 1:40below 0 or above 1:40
U/mL0 – 2020 – 24.9below 0 or above 24.9

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: One of the few antibodies specific enough to act on. EASL treats a titre of 1:40 with a cholestatic alkaline phosphatase as diagnostic of primary biliary cholangitis without biopsy, and the British guideline counts a titre above 1 in 40 as positive; it can precede abnormal enzymes by years — so read it beside ALP and GGT rather than alone. A titre of 1:40 is shown as acceptable only because the two guidelines differ on whether 1:40 itself counts; 1:80 and above is out of range. The M2 ELISA in U/mL is a different assay from the titre and its band is its own: 20 or less is negative, 20.1 to 24.9 equivocal and 25 or more positive at ARUP and Labcorp. The two do not convert.

Sources

  • The British Society of Gastroenterology/UK-PBC primary biliary cholangitis treatment and management guidelines — Hirschfield GM, Dyson JK, Alexander GJM, et al. — Gut, 2018 · Clinical guidelineAMA above 1 in 40 with cholestatic liver biochemistry and no other explanation is usually sufficient to diagnose PBC; a titre above 1 in 40 is conventionally positive, and low-titre AMA with normal liver tests is seen in about 0.5% of people. Supports ending the acceptable band at 1:40 rather than 1:80. Full text read through the Europe PMC full-text service for PMC6109281.
  • Mitochondrial M2 Antibody, IgG (ELISA) — ARUP Laboratories, 2026 · Laboratory / reference-interval source20.0 units or less is negative, 20.1 to 24.9 equivocal, 25.0 or greater positive. Matches Sera's optimal upper edge of 20 and puts the positive cut-off at 25, not 30. Labcorp's M2 test uses the same three bands. Test directory page as opened in October 2026.
  • Mitochondrial (M2) Antibody — Labcorp, 2026 · Laboratory / reference-interval sourceNegative 0.0 to 20.0, equivocal 20.1 to 24.9, positive above 24.9. A second laboratory with the same M2 bands as ARUP. Test directory page as opened in October 2026; it does not print the unit.
  • EASL Clinical Practice Guidelines: The Diagnosis and Management of Patients with Primary Biliary Cholangitis — European Association for the Study of the Liver, 2017 · Clinical guidelineEstablishes AMA at 1:40 or above, alongside a cholestatic alkaline phosphatase, as sufficient for diagnosing primary biliary cholangitis without biopsy, and records the roughly 90-95% prevalence in the disease. Sera's optimal band stops below that dilution.

Last reviewed: November 9, 2026 · AMA on its own page

Anti-Smooth Muscle Antibody (ASMA)Established clinical thresholdAssay-dependenttiter

An antibody against smooth muscle actin, and with ANA one of the two markers of type 1 autoimmune hepatitis.

UnitOptimalSufficientOut of range
titer0 – 1:201:20 – 1:80below 0 or above 1:80

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: Scored rather than diagnostic: the IAIHG simplified criteria count a titre from 1:40 as weak support for autoimmune hepatitis and from 1:80 as stronger, always alongside IgG, histology and exclusion of viral hepatitis. The bands follow the laboratory reading of the same test: below 1:20 is the reference interval, 1:20 to 1:80 is a weak positive worth repeating, and 1:160 or more is positive. Low titres occur in other liver disease and in health, so this marker means little away from raised transaminases.

Sources

  • British Society of Gastroenterology guidelines for diagnosis and management of autoimmune hepatitis — Gleeson D, Bornand R, Brownlee A, et al. — Gut, 2025 · Clinical guidelineTable 6, the simplified diagnostic criteria adapted from Hennes: ANA or ASMA at a titre above 1:40 scores +1 and above 1:80 scores +2, alongside IgG, histology and absence of viral hepatitis. Supports the 1:40 and 1:80 steps behind Sera's bands. Full text read through the Europe PMC full-text service for PMC12421125.
  • Smooth Muscle Antibody, IgG Titer — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceReference interval less than 1:20; 1:20 to 1:80 is weak positive with a repeat suggested in two to three weeks; 1:160 or greater is positive and suggestive of autoimmune hepatitis. The same split as Sera's sufficient band of 20 to 80. Test directory page as opened in October 2026.

Last reviewed: November 9, 2026 · ASMA on its own page

Anti-Ovarian AntibodiesNo universal rangeUnbandedAssay-dependenttiter · unbanded

Antibodies against ovarian tissue, read by immunofluorescence on a section of ovary and reported as a titre.

No universal Sera range published.

The test is poorly standardised and guidelines advise against relying on it. Read this marker against the interval printed by the issuing laboratory.

Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.

Interpretation: There is no agreed range for anti-ovarian antibodies. The 2024 ESHRE, ASRM and IMS guideline on premature ovarian insufficiency states that this test should not be used to diagnose autoimmune POI, and recommends 21-hydroxylase antibodies and TSH instead. Laboratories that still offer it report negative or a titre by immunofluorescence, with the screening dilution set by the laboratory (1:5 at Quest; 1:10 at others). A positive result does not establish autoimmune oophoritis and a negative result does not exclude it. Read the result against the cut-off printed on the report.

Sources

  • Evidence-based guideline: premature ovarian insufficiency — ESHRE, ASRM, CREWHIRL and IMS Guideline Group on POI — Human Reproduction Open, 2024 · Clinical guidelineStrong recommendation that anti-ovarian antibody screening should not be used to diagnose autoimmune POI; 21-hydroxylase antibodies should be measured in POI of unknown cause, and TSH at diagnosis. Routine TPO antibody screening is advised against. This gives no titre and does not support any band for ovarian antibodies.
  • Ovarian Antibody Screen with Reflex to Titer, IFA — University of Washington Department of Laboratory Medicine and Pathology (performed by Quest Diagnostics Nichols Institute), 2026 · Laboratory / reference-interval sourceImmunofluorescence screen with a reference of Negative, run at a 1:5 dilution, with a titre only if the screen is positive. A laboratory screening at 1:5 reports 1:5 as positive, which Sera's proposed cut-off of 1:10 would score as negative.

Last reviewed: November 9, 2026

Patterns Sera flags

Combinations of results the literature describes, which Sera points out under the relevant trend chart when a client's results fit. Each is listed with the rule that triggers it and its sources. A match is observational pattern-matching, not a diagnosis. The interpretation stays with the practitioner.

Range set: Sera Production · Version 1.0 · Production · Last reviewed November 9, 2026. These ranges are read from the same configuration the Sera application uses to interpret results, so this page and the app can never disagree.