Tissue Transglutaminase IgA (tTg-IgA) Blood Test

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

A tTg-IgA blood test checks the level of tTg-IgA in blood. Doctors might order a tTg-IgA test if kids have signs of celiac disease. Symptoms can include poor growth, belly pain, bloating, constipation (trouble pooping), vomiting, diarrhea, and rashes.

Doctors might also do the test if a child has a condition that makes celiac disease more likely (such as type 1 diabetes or thyroid disease) or a family member with celiac disease.

What Is tTg-IgA?

tTg-IgA stands for tissue transglutaminase-immunoglobulin A:

tTg (short for tissue transglutaminase) is a kind of protein in the intestines called an enzyme.
IgA (short for immunoglobulin A) is another type of protein called an antibody. The immune system makes antibodies to recognize and get rid of germs and other things it sees as threats.

In celiac disease, the immune system mistakenly thinks that gluten — a protein in wheat, barley, rye, and oats — is a foreign invader. So the immune system makes antibodies that attack tTg.

Top Things to Know

The tTg-IgA blood test checks the level of tTg-IgA in the blood.
The test helps doctors diagnose celiac disease.
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 tTg-IgA level is too high.

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.

For the test results to be accurate, your child should be on a diet that includes gluten until the test is done. If kids don’t eat gluten, there won’t be any tTg-IgA, and doctors won’t be able to use this test to know if your child has celiac disease.