Total Immunoglobulin G (IgG) in Serum

What Does IgG Measure?

IgG is the most abundant antibody in your blood, produced by your immune system to fight off bacteria and viruses. It helps remember past infections and provides protection against future exposures. Levels can vary based on your immune health, age, and overall health status.

Why Might Your Doctor Order This Test?

Your doctor may order an IgG test if you have symptoms like frequent infections, unexplained illnesses, or if you’re being evaluated for conditions like HIV, autoimmune diseases, or immune deficiencies. It can also be part of routine monitoring for certain treatments.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab where it is tested for IgG levels using an immunoassay method, which detects the presence and concentration of antibodies.

What Are Common Results?

Results are typically reported as a concentration in grams per liter (g/L) or milligrams per deciliter (mg/dL). While reference ranges can vary by lab, lower than expected levels may suggest immune system issues, while higher levels might indicate chronic infections or other conditions.