Serum or plasma mass concentration of immunoglobulin G (IgG) by nephelometry or turbidimetry

What Does IgG Serve in Your Body?

IgG is the most common type of antibody in your blood. It plays a critical role in defending against bacterial and viral infections. After an infection is cleared, IgG helps provide long-term immunity by remembering past invaders to prevent future illnesses. Low levels may indicate immune system issues, while high levels could be due to chronic infections or certain medical conditions.

When Might You Need This Test?

Your doctor may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It may also be used to monitor conditions like autoimmune diseases, certain cancers, or to check for immune deficiencies in newborns or people with HIV.

What to Expect During the Test

A blood sample is taken from a vein, usually in your arm. You may feel a small pinch, but it usually doesn’t cause significant discomfort. The sample is then sent to a lab to measure IgG levels using a nephelometry or turbidimetry method, which detects the concentration of antibodies in your blood.

Possible Results and Next Steps

Results are typically reported as a mass concentration (e.g., grams per liter). If your IgG level is outside the expected range, your doctor will discuss what this means for you. They may recommend further testing or treatments based on the cause of any abnormalities.