Immunoglobulin A (IgA) in Serum or Plasma

What Does IgA Serve in Your Body?

IgA is the most abundant antibody in your body and plays a key role in protecting mucous membranes, such as those in your respiratory and digestive tracts. It helps prevent harmful bacteria and viruses from entering your body through these surfaces. IgA is also found in saliva, tears, and breast milk, where it provides early protection to infants.

Why Might You Need This Test?

Doctors may order an IgA test to check for immune system issues, such as low IgA levels, which can be linked to conditions like recurrent infections, certain autoimmune diseases, or immune deficiencies. It may also be used in the evaluation of conditions like cystic fibrosis, celiac disease, or to monitor immune responses in certain treatments.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The blood is then sent to a lab for analysis. The test measures the concentration of IgA in your serum or plasma, depending on the type of specimen collected.

What Are Possible Results?

Results are typically reported as a concentration value (e.g., milligrams per deciliter, mg/dL). While reference ranges can vary slightly between labs, lower than expected levels may suggest immune system problems, while higher levels might be investigated for conditions like certain autoimmune diseases or chronic infections.