Vitamin B6 optimal range and reference range

Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026

Sera's bands for Vitamin B6:

Optimal 30 – 110 nmol/L (7.5 – 27 μg/L); sufficient 20 – 150 nmol/L (5 – 37 μg/L); out of range below 20 or above 150 nmol/L.

Evidence grade: 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.

All units

Unit	Optimal	Sufficient	Out of range
nmol/L	30 – 110	20 – 150	below 20 or above 150
μg/L	7.5 – 27	5 – 37	below 5 or above 37

What the evidence says

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.

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

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.

What Vitamin B6 measures

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).

Low B6 can cause tiredness, low mood, irritability, and tingling in the hands and feet. It works closely with folate and B12 to keep homocysteine in check, so it is best read alongside those. Very high levels from too much supplementation can also harm the nerves, so more is not always better.

Related vitamins & minerals markers

See Vitamin B6 in the full list of biomarker ranges

This page is a reference for practitioners, not medical advice. Sera's bands are practitioner targets for structured review, not diagnostic thresholds, and Sera does not diagnose or recommend treatment. Read a result alongside the interval printed by the issuing laboratory and the client's history and symptoms. Range set: Sera Production, version 1.0, last reviewed November 9, 2026.