Immunoglobulin G (IgG) Subclass 1 and 3 Antibody Levels (Serum)

Why This Test Is Done

Doctors may order this test if you have symptoms of a weakened immune system, such as frequent infections, unusual bruising, or unexplained bleeding. It may also be used to evaluate immune responses after vaccination, diagnose autoimmune diseases, or monitor conditions like HIV, lupus, or certain cancers.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into a vein (usually in your arm) to draw blood. The process usually takes a few minutes. If you’re nervous, let your healthcare provider know—you can take medicine or use distraction techniques if needed.

What the Test Results Mean

Results show levels of IgG1 and IgG3 antibodies, which are part of your immune system’s defense. Low levels may indicate an immune disorder, while high levels could suggest an overactive immune response or certain infections. Your doctor will interpret the results in the context of your health history.

Common Conditions Monitored

This test helps diagnose or track conditions like chronic infections, autoimmune diseases (such as rheumatoid arthritis or systemic lupus erythematosus), HIV/AIDS, or immune deficiencies. It may also be used to check how well vaccines are working in people with weakened immune systems.