IgA (Immunoglobulin A) Blood Test

What Is the IgA Blood Test and Why Is It Done?

An IgA (immunoglobulin A) blood test checks the level of IgA in blood. The main reason doctors order an IgA test is to see why someone keeps getting infections. They may also order the test if there might be:

problems with intestines or kidneys
certain autoimmune conditions (when the immune system damages normal, healthy body tissues), like lupus, celiac disease, and juvenile idiopathic arthritis

What Is IgA?

IgA is a kind of protein called an antibody, or immunoglobulin. The immune system makes antibodies to recognize and get rid of germs and other things it sees as threats. IgA is one of the most common antibodies in the body. It’s usually found in mucous membranes (tissue that lines and protects the inside of your body) in places like the nose, throat, intestines, and stomach. IgA is also in saliva (spit), and tears.

IgA in mucous membranes helps protect the body from germs. If there’s not enough IgA, a person might be more likely to get an infection from those germs.

With some autoimmune conditions, like celiac disease, the immune system mistakenly thinks that certain non-germs, like gluten (a protein in wheat, barley, rye, and oats) are harmful. So the immune system makes extra antibodies that attack healthy tissues.

Top Things to Know

The IgA (immunoglobulin A) blood test checks the level of IgA in the blood.
The test helps doctors diagnose problems with the immune system, like frequent infections.
Kids might need to stop taking certain medicines or not eat or drink before the blood test.
Your doctor can explain what it means if the IgA level is high or low.

How Can I Help My Child Prepare for a Blood Test?

To help kids get ready for a blood test, find out if they need to fast (not eat or drink) or should stop taking medicines before the test. Explain what to expect during the test. If your child is nervous about it, work together on ways to stay calm. Deep breathing or even imagining being in a place that makes your child feel safe and calm can help.

What Do IgA Test Results Mean?

Abnormal IgA levels may mean that someone has a greater chance of having an autoimmune condition, infections, asthma, and allergies. Sometimes kids are born with low levels of IgA — or none at all. More tests may be needed to see if a person has a certain condition for sure.

Your doctor will explain what the results of the IgA test mean for your child. What’s “normal” varies based on things like age and gender.

What Else Should I Know?

If your doctor would like your child to have an IgA blood test, you might hear it called an IgA serum test (“serum” is another word for blood). It may also be known as an IgA lab test because it’s checked in a lab.

When kids have an IgA test, sometimes they’ll have other kinds of antibodies tested too, like immunoglobulin G (IgG).

If you have questions about the IgA test, talk to your doctor.