Serum Immunoglobulin G (IgG) Level

What Is Immunoglobulin G (IgG)?

IgG is the most common type of antibody in your blood. It plays a key role in protecting your body from infections by recognizing and neutralizing harmful substances, such as bacteria and viruses. Levels of IgG can vary depending on your immune response, overall health, and certain medical conditions.

Why Might You Need This Test?

Doctors may order an IgG test to diagnose or monitor conditions like immunodeficiency, autoimmune diseases, infections, or to check immune function before certain treatments. It can also help evaluate long-term immune health, especially in people with chronic illnesses or those who have had organ transplants.

What to Expect During the Test

A blood sample is taken from a vein, usually in your arm. You may feel a slight pinch, but it typically doesn’t cause significant discomfort. The sample is then sent to a lab for analysis.

Possible Results and Interpretation

Results are compared to a general reference range, which can vary by lab. Low IgG levels may suggest weakened immunity, while very high levels could indicate chronic infections, certain cancers, or other immune-related conditions. Your doctor will discuss your specific results in the context of your health history.