IgG 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 IgG:

  • Optimal 700 – 1,600 mg/dL (7 – 16 g/L); sufficient 600 – 1,600 mg/dL (6 – 16 g/L); out of range below 600 or above 1,600 mg/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
mg/dL700 – 1,600600 – 1,600below 600 or above 1,600
g/L7 – 166 – 16below 6 or above 16

What the evidence says

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.

What Immunoglobulin G (IgG) measures

The most abundant antibody class in the blood, and the measure of long-term humoral immunity.

A bare IgG is the total across all four subclasses, and a different test from any of the antigen-specific IgG antibodies on a coeliac or thyroid panel. A high level with raised transaminases supports autoimmune hepatitis; a low one raises immunodeficiency and is the finding that makes recurrent infection worth investigating.

Related autoimmune markers

See IgG 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.