Indicator Explainer

IgG

An immunoglobulin isotype (subclass) that characterizes secondary immune responses. This isotype is further broken down into several smaller subclasses (IgG1, IgG2a, IgG2b, IgG3 in the mouse; IgG1-4 in the human), and each subclass is differentially synthesized and secreted into the serum upon differential immune stimuli.

Reviewed 2026-10-18
Read this first

This page explains what the indicator is and how results are interpreted in general terms. Reference ranges depend on the laboratory, the method, and your own situation — no single “normal value” applies to everyone. This page is health information, not a diagnosis. For symptoms, treatment, or urgent concerns, contact a healthcare professional.

When it is tested

Source: National Cancer Institute, NCI Thesaurus 26.09d, C568. NCI definition, reproduced without modification under CC BY 4.0. Source identity and definition checked automatically on 2026-10-18. No individual clinical interpretation or human reviewer is asserted.

Reading results

Reference intervals and interpretation depend on the laboratory, specimen, method and clinical context. This source definition is educational information; it does not establish a diagnosis, product approval or suitability for an individual.

Also Known As

IgGImmunoglobulin G