Immunoglobulin A (IgA) in Serum or Plasma

What Does This Test Measure?

IgA is one of the main antibodies your immune system produces. It helps protect your mucous membranes, such as those in your nose, throat, and digestive tract, from harmful bacteria and viruses. Your body produces IgA in different forms, including secretory IgA, which is found in saliva, tears, and breast milk. This test specifically looks at the total IgA in your blood, which can indicate how well your immune system is functioning in certain areas.

Why Might You Need This Test?

Doctors may order an IgA test to diagnose or monitor conditions like immune deficiencies, certain autoimmune diseases (such as lupus or rheumatoid arthritis), or to check for problems with how your body produces antibodies. It can also be used in research or to evaluate immune responses to vaccines or infections.

What Does a Low or High IgA Level Mean?

Low IgA levels may suggest an immune system disorder, such as selective IgA deficiency, which can make you more prone to infections. High levels might be seen in some autoimmune conditions or during certain infections, but they are not always clinically significant on their own. Results should be interpreted by a healthcare provider in the context of your overall health and symptoms.

How Is This Test Done?

A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab where it is processed to measure the IgA concentration. The test can be performed on serum or plasma, depending on the lab’s method.