Anti-tissue Transglutaminase Antibody

Does this test have other names?

IgA anti-tissue transglutaminase, IgA Anti-tTG, celiac disease testing

What is this test?

This test is used to see if you have celiac disease. It is also used to see how well people with the condition are doing. It is one of several blood tests that may be used to help diagnose celiac disease.

Tissue transglutaminase is an enzyme that fixes damage in your body. People with celiac disease often make antibodies that attack this enzyme. These are called anti-tissue transglutaminase antibodies. A blood test that shows higher levels of anti-tissue transglutaminase antibodies can help your healthcare provider figure out if you have celiac disease. 

Why do I need this test?

If you have celiac disease, you are allergic to gluten. Gluten is the protein found in wheat, rye, and barley. Celiac disease is an autoimmune disorder. This means your body attacks itself. With celiac disease, your body attacks the lining of the small bowel, making it less able to absorb nutrients. The sensitivity to gluten can also cause pain in the abdomen, low blood count (anemia), tiredness, muscle and joint pain, gas, diarrhea, vomiting, weight loss, and malnutrition. 

What other tests might I have along with this test?

If your healthcare provider thinks you have celiac disease, he or she may order several other blood tests. These may look for generalized inflammation (C reactive protein or erythrocyte sedimentation rate) or poor absorption of nutrients (iron deficiency, low cell counts, or unabsorbed fat in stool). 

Your provider may also take a tissue sample (biopsy) from your small bowel to confirm the blood tests' findings. The biopsy is important to confirm a diagnosis of celiac disease. It should be done when possible. The biopsy is done using a tubelike device (endoscope) put down your throat and into the small intestine. Your provider uses it to get the sample without doing surgery. 

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

Keep in mind that no one test can say for sure that you have celiac disease. Your healthcare provider will use other things to help confirm the diagnosis.

The higher the levels of anti-tissue transglutaminase antibodies in your blood, the more likely it is that you have it or a related disorder. Younger children are an exception to this rule. A test may come back negative even if the child has celiac disease. But other tests can give a proper diagnosis.  

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.  

What might affect my test results?

This test is considered the best and most specific blood test for diagnosing celiac disease. But 2% to 3% of people with celiac disease don't have enough IgA antibodies, the substance the test looks for. This can lead to a false-negative result.

In addition, the test is not as accurate for young children. Other tests may need to be done to confirm celiac disease.  

How do I get ready for this test?

If the test is to diagnose celiac disease, it is best to have it before you stop eating gluten. This is because the lack of gluten could give a negative test result even if you have celiac disease. If the test is to see how well you are doing with celiac disease, you don't need to get ready for the test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.