Immunoglobulin G (IgG) in Serum

What Does This Test Measure?

IgG is the most abundant antibody in your blood and plays a key role in long-term immunity. It helps your immune system fight off bacteria and viruses by marking them for destruction. Measuring IgG helps doctors assess your immune system’s strength and identify issues like low immunity, infections, or certain immune disorders.

Why Might You Need This Test?

Your doctor may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, slow healing of wounds, or unexplained fatigue. It may also be used to monitor immune responses to treatments like chemotherapy, vaccines, or medications that affect immunity.

Sample Collection and Preparation

A blood sample is taken from a vein in your arm. You may feel a small pinch when the needle is inserted, but the procedure is quick. The blood is then sent to a lab for analysis. No special preparation is needed, but avoid eating or drinking for a few hours before the test if instructed.

What to Expect After the Test

After the blood is drawn, you can return to your normal activities. You may experience mild bruising, swelling, or discomfort at the injection site, which usually goes away within a day or two. Follow-up instructions from your doctor will guide you on next steps, such as when to expect results.