Serum IgG Immunoglobulin (Total)

This test measures the level of immunoglobulin G (IgG) in your blood. IgG is the most abundant type of antibody, a protein your immune system makes to help fight bacteria, viruses, and other harmful invaders. Checking your IgG level can show how well your immune system is working.

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 broad protection against pathogens like bacteria and viruses. This test quantifies the total concentration of IgG in your serum sample.

You may need this test if your doctor suspects your immune system is not working as it should, if you have frequent or unusual infections, or if you have a condition that can affect antibody levels. It can also be used to monitor an immune disorder or to see how your body is responding to treatment.

Doctors may order an IgG test to diagnose or monitor conditions affecting your immune system, such as infections, autoimmune diseases, or immune deficiencies. It can also help assess how well vaccines are working or evaluate immune responses in chronic illnesses.

Common reasons for this test include repeated or severe infections, chronic digestive problems, suspected immune deficiency, monitoring conditions that affect antibody production, and checking immune function before certain treatments. Your doctor may also order it to follow up on abnormal findings from earlier blood work.

Common reasons include diagnosing immune system disorders (e.g., hypogammaglobulinemia), evaluating immune responses post-vaccination, checking for infections, or monitoring conditions like lupus, rheumatoid arthritis, or HIV.

This test requires a small blood sample, usually taken from a vein in your arm by a trained professional. In most cases, no special preparation is needed, and you can eat and drink normally beforehand. Let your care team know about any medicines, vitamins, or supplements you take, since some can affect the results.

A blood sample is drawn from a vein in your arm. The blood is processed to separate serum (the liquid part without clotting factors) for testing. This test does not require fasting or special preparation beyond standard blood draw procedures.