Immunoassay for Immunoglobulin G (IgG) Subclasses (A, D, E) in Serum

Why This Test Is Done

Your doctor may order this test if they suspect an immune system issue, such as a deficiency in certain IgG subclasses, an overactive immune response, or how your body is responding to treatments like vaccines or medications. It can also be used to evaluate chronic conditions like lupus, rheumatoid arthritis, or other autoimmune diseases.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before your blood draw if your doctor recommends it, but this is not always required. Bring any medications you’re currently taking, as some may affect test results.

What the Test Involves

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure usually takes just a few minutes. The blood sample will be sent to a lab for analysis.

What the Results Mean

IgG antibodies are divided into four subclasses (IgG1, IgG2, IgG3, IgG4). Each subclass plays a different role in immunity. Abnormal levels of any subclass may indicate an immune disorder, infection, or how well your body is producing antibodies. Your doctor will interpret the results in the context of your overall health and symptoms.