Immunoglobulin G (IgG) in Serum or Plasma

Why This Test Is Done

Doctors may order an IgG test to check for immune system issues, such as low levels of antibodies that could make you more prone to infections. It might also be used to monitor conditions like HIV, lupus, or other autoimmune diseases where antibody levels can change over time. Additionally, it can help diagnose or manage certain immune disorders or infections in infants or newborns.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into a vein in your arm, and a blood sample will be drawn. If you’re taking blood from your finger, it may feel slightly uncomfortable but shouldn’t cause significant pain. If you’re pregnant, breastfeeding, or have a history of bleeding disorders, let your healthcare provider know before the test.

What Happens During the Test

The test involves drawing a small amount of blood from your arm using a needle. The blood is then sent to a lab for analysis. The process usually takes a few minutes. If you experience any discomfort, your healthcare provider can apply a numbing cream or use a smaller needle.

What the Results Mean

Results are typically reported as a concentration of IgG in the blood. While specific reference ranges can vary by lab, very low levels may suggest an immune deficiency, while very high levels could indicate conditions like multiple myeloma or certain infections. Your doctor will interpret the results in the context of your overall health and medical history.