Serum IgG Immunoglobulin Subclass Concentration (Subclasses A, D, E, G) via Immunoassay

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like frequent infections, unusual immune responses, or if they suspect a condition affecting your immune system, such as certain autoimmune diseases or immune deficiencies. It may also be used to monitor treatment effectiveness for conditions like lupus, rheumatoid arthritis, or chronic infections.

What to Expect During the Test

A small blood sample is drawn from a vein in your arm. The blood is processed to separate serum, which is then tested for IgG subclass levels using a sensitive immunoassay method. The process typically takes about 15–30 minutes, and you may feel a slight pinch during the blood draw.

What the Results Mean

Results show the concentration of each IgG subclass (A, D, E, G) in your serum. While reference ranges vary slightly by lab, lower-than-expected levels in certain subclasses may indicate immune system dysfunction, while higher-than-expected levels might suggest overactive immune responses or certain infections.

Common Conditions Linked to IgG Subclass Testing

Abnormal IgG subclass levels can signal underlying conditions such as primary immunodeficiency diseases, autoimmune disorders (e.g., systemic lupus erythematosus), chronic infections (e.g., HIV), or certain types of cancer (e.g., multiple myeloma). Your provider will interpret results in the context of your symptoms and medical history.