Globulin 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 Globulin:

  • Optimal 2.4 – 3 g/dL (24 – 30 g/L); sufficient 2 – 3.5 g/dL (20 – 35 g/L); out of range below 2 or above 3.5 g/dL.

Evidence grade: 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.

All units

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

What the evidence says

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.

What Globulin measures

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.

Globulins reflect immune activity, inflammation, and liver function. High levels can point to long-term infection, inflammation, autoimmune disease, or rarely a blood disorder, while low levels can mean a weak immune system or reduced liver production. It is best read with albumin through the A/G ratio.

Related liver & pancreas health markers

See Globulin in the full list of biomarker ranges

About the author

Alina Radu is the founder of Sera and a software engineer. The idea started with her own Hashimoto's tests, scattered across years without the big picture. She is not a clinician: these ranges are compiled from the published sources linked on each page, with every source named. Alina Radu on LinkedIn

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.