Immunoglobulin G (IgG) Subclass 2, Serum

What Does This Test Measure?

IgG2 is one of five subclasses of Immunoglobulin G (IgG), a key part of your immune system. It plays a role in defending against certain types of bacteria and some viruses. This test specifically looks at the concentration of IgG2 in your serum, which can help assess how well your immune system is functioning against specific pathogens.

Why Might You Need This Test?

Doctors may order an IgG2 test if you have symptoms or conditions that suggest an immune system issue, such as recurrent infections, certain autoimmune diseases, or if you’re being evaluated for immune-related treatments. It can also be part of a broader immune function assessment.

What to Expect Before the Test

No special preparation is usually needed for this blood test. You may be asked to fast for 8–12 hours before the test if it’s part of a metabolic or liver function panel, but this is not always required for IgG2 alone. Bring any medications or supplements you’re taking to your appointment.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm using a small needle. The process is quick and typically causes only mild discomfort. The blood sample will be sent to a lab for analysis using an immunoassay method to measure IgG2 levels.