Immunoglobulin G (IgG)

High IgG usually indicates past or ongoing immune stimulation: chronic or recent infection, long-standing inflammation, autoimmune disease, or response to vaccination. It can also reflect monoclonal or polyclonal gammopathy (e.g., MGUS, multiple myeloma) or liver disease. Interpretation requires clinical context and further tests (IgG subclasses, electrophoresis, specific antibody titers). Discuss results with your physician.

Immunoglobulin G (IgG) is the most abundant antibody in blood and extracellular fluid; it neutralizes pathogens and toxins, opsonizes microbes for phagocytosis, activates complement, and mediates antibody‑dependent cellular cytotoxicity. IgG provides long‑term and memory immune protection, dominates secondary immune responses, and crosses the placenta to confer passive immunity to the fetus.

Low IgG means you have reduced levels of a key antibody that helps fight infections. It can cause recurrent sinopulmonary infections (sinusitis, bronchitis, pneumonia), poor vaccine response, and slower recovery. Causes include primary immune disorders or secondary loss from medications, protein-losing conditions, or blood cancers. Evaluation involves repeat Ig measurements, vaccine antibody titers, and specialist referral; severe cases may need immunoglobulin replacement.

The immunoglobulin G (IgG) test measures IgG antibody levels in blood to determine past exposure or immunity to specific infections and to assess vaccine response. It also helps detect immune deficiencies (low IgG), chronic or resolved infections, and certain autoimmune or gammopathy conditions (elevated IgG). Specific IgG assays target particular pathogens; total IgG evaluates overall antibody status.

Stress can dysregulate the immune system and alter immunoglobulin (Ig) levels. Acute stress may transiently shift antibody responses; chronic psychological stress has been associated with altered IgG production and increased autoantibody risk in some people. However, stress alone isn’t a proven sole cause of persistently high IgG—abnormal results should prompt medical evaluation to identify infections, autoimmune disease, or other causes.

Treatment for high IgG depends on the cause. Chronic infections are treated with appropriate antimicrobials; autoimmune disorders are managed with immunosuppressants (corticosteroids, DMARDs, biologics) and sometimes plasmapheresis for severe antibody‑mediated disease. Monoclonal gammopathies require hematology-directed therapy (chemotherapy, targeted agents, stem cell transplant). Mild, asymptomatic elevations may only need monitoring and specialist follow-up.