Immunoglobulin G (IgG) Subclass Quantification by Serum Protein Electrophoresis

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like frequent infections, unusual bleeding, or if you’ve been diagnosed with a condition that affects antibody production, such as common variable immunodeficiency (CVID). It may also be used to monitor treatment responses in certain autoimmune or immune-related diseases.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your vein (usually in your arm) to draw blood. The process usually takes a few minutes, and you may feel a brief pinch. If you’re nervous about needles, let your healthcare provider know.

What the Test Results Mean

IgG antibodies are divided into four subclasses (IgG1, IgG2, IgG3, IgG4). Abnormal levels of any subclass can indicate immune system issues. For example, low IgG2 levels might suggest problems with bacterial infections, while low IgG4 could be linked to certain autoimmune conditions. Your results will be compared to a reference range specific to your age and health status.

Common Conditions Linked to IgG Subclass Testing

IgG subclass testing is often used to diagnose or evaluate conditions such as primary immunodeficiency diseases, autoimmune disorders (like rheumatoid arthritis), or chronic infections. It can also help assess immune responses to vaccines or treatments like intravenous immunoglobulin (IVIG).