The Immunoglobulin M (IgM) test measures the level of IgM antibodies in the blood, which are the first antibodies produced by the immune system in response to an infection. IgM plays a crucial role in the initial immune response, indicating a current or recent infection. This test is often used to diagnose acute infections, assess immune function, and evaluate certain autoimmune or immunodeficiency disorders.

Preparation: No special preparation or fasting is required.

Procedure: A blood sample is drawn from a vein, usually in the arm.