Serum or plasma mass concentration of immunoglobulin G (IgG) fragments or related proteins (e.g., F(ab')₂ fragments)

What This Test Measures

IgG is a key part of your immune system, helping fight infections. When IgG breaks down, it can form smaller fragments. This test specifically looks at the concentration of these fragments in your blood. The results may be useful in diagnosing or monitoring conditions like immune deficiencies, certain autoimmune diseases, or after treatments that affect antibody levels.

Why It Might Be Ordered

Your healthcare provider may order this test if you have symptoms like frequent infections, unusual bleeding, or if you’re being treated for a condition that could alter antibody structure. It may also be part of a broader evaluation for immune system disorders or after receiving therapies that impact antibodies.

Common Reasons for Testing

This test is less commonly performed than standard IgG tests but may be used in specialized cases, such as research, rare genetic disorders, or monitoring immune-related treatments. Always discuss the reason with your doctor.

Sample Collection and Preparation

Blood is drawn from a vein in your arm. The sample is processed to separate serum or plasma, then analyzed for IgG fragments. Avoid alcohol or strenuous activity 24 hours before testing for best results.