Immunoglobulin G (IgG) Substance Concentration in Serum

What Is Immunoglobulin G (IgG)?

IgG is the most common type of antibody in your blood. It plays a key role in fighting off infections by helping your immune system recognize and remember harmful substances, such as bacteria and viruses. IgG antibodies are produced by your immune system in response to exposure to pathogens (disease-causing organisms).

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It can also be used to monitor immune responses in certain conditions, like chronic infections or autoimmune diseases.

When Is This Test Performed?

This test is typically done through a simple blood draw. You may be asked to fast for a few hours before the test, but this is not always required. The blood sample is sent to a lab for analysis, and results are usually available within a few days.

What Does the Test Result Mean?

Results are compared to standard ranges to determine if your IgG levels are within normal limits, lower than normal (hypogammaglobulinemia), or higher than normal. Low IgG levels may indicate an immune deficiency, while high levels could be due to chronic infections, certain medications, or other health conditions.