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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 screen for celiac disease. It also monitors the progress of people with the condition. It is one of several blood tests that may be used to help diagnose celiac disease.

Tissue transglutaminase is an enzyme that repairs damage in the body. People with celiac disease often make antibodies that attack tissue transglutaminase. They are called anti-tissue transglutaminase antibodies, or immunoglobin A (IgA) antibodies. Therefore, a blood test that shows higher levels of anti-tissue transglutaminase antibodies can help your doctor figure out if you have celiac disease. 

Why do I need this test?

If you have celiac disease, you have an allergy to gluten, the protein found in wheat, rye, and barley. Celiac disease is an autoimmune disorder, which means that your body attacks itself. This process damages the lining of the small bowel, reducing its ability to absorb nutrients, The sensitivity to gluten can also cause pain in the abdomen, anemia, fatigue, muscle and joint pain, gas, diarrhea, vomiting, weight loss, and malnutrition. 

What other tests might I have along with this test?

If your health care provider suspects that you have celiac disease, he or she may order several other blood tests. These may look for antigliadin antibodies and antiendomysium antibodies.

In addition, your doctor may take a tissue sample, or biopsy, from your small bowel to confirm the blood tests' findings. This biopsy is considered key in confirming a diagnosis of celiac disease and should be done when possible. The biopsy is done using an endoscope, a tubelike device inserted down your throat and to the small intestine. Your doctor uses it to collect the sample without the need for surgery. 

What do my test results mean?

A result for a lab test may be affected by many things, including the method the laboratory uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

The higher the levels of anti-tissue transglutaminase antibodies in your blood, the more likely it is that you have celiac disease 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. Other tests can give a proper diagnosis, however.  

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly 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 percent 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, and 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 should ideally be done before you remove gluten from your diet. This is because the absence of gluten could give a negative test result even if you have celiac disease. If the test is to monitor a current case of celiac disease, you don't need to prepare for the test.