Serum or plasma immunoglobulin G (IgG) concentration

What Does IgG Measure?

IgG is the primary antibody produced by your immune system in response to infections, vaccines, and other immune challenges. It circulates in your bloodstream and provides long-lasting protection against pathogens like bacteria and viruses. This test helps assess your overall immune function, especially after exposure to infections or vaccinations.

Why Might You Need This Test?

Your healthcare provider may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, slow healing wounds, or unexplained fatigue. It may also be used to monitor immune responses after vaccination, diagnose conditions like immunodeficiency disorders, or evaluate immune recovery post-infection.

Sample Collection and Preparation

A blood sample is taken from a vein in your arm. The blood is then separated into serum (liquid part without clots) or plasma (liquid part with clots dissolved) for testing. This test can be performed on either serum or plasma samples.

Test Method and Process

IgG levels are typically measured using an immunoassay method, which detects and quantifies the specific antibody in your blood. This method relies on antibodies that bind to IgG, triggering a measurable reaction that indicates the concentration of IgG in your sample.