The Immunoglobulin A (IgA) test measures the level of IgA antibodies in the blood, which are essential for immune function, particularly in the mucous membranes of the respiratory and gastrointestinal tracts. This test helps diagnose immune system disorders, certain autoimmune conditions, chronic infections, and IgA deficiencies.

Preparation: No special preparation or fasting is required.

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