Serum Immunoglobulin G (IgG) Level

What Does IgG Serve in Your Body?

IgG is the most abundant antibody in your blood and plays a critical role in long-term immunity. It helps your body recognize and remember pathogens (like bacteria and viruses) to fight them more effectively in the future. IgG also crosses the placenta to provide passive immunity to your newborn.

Why Might Your Doctor Order This Test?

Your doctor may order an IgG test to check for low or high levels, which can indicate conditions like immune deficiencies, infections, autoimmune diseases, or certain types of cancer. It’s also used to monitor treatment responses in patients with chronic illnesses.

Common Reasons for Testing

Common reasons include diagnosing or monitoring conditions such as HIV/AIDS, chronic infections, autoimmune diseases (like lupus or rheumatoid arthritis), or immune system disorders. It may also be checked in newborns to assess maternal antibody transfer.

Sample Collection and Preparation

This test requires a blood sample drawn from a vein in your arm. You may feel a small pinch when the needle is inserted, but it usually doesn’t cause significant discomfort. The blood is collected in a special tube and sent to the lab for analysis.