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Allergy & Intolerance

Anti-TTG IgA: What Does This Coeliac Disease Marker Tell You?

Anti-TTG is the recommended first-line blood test for coeliac disease screening. Including this marker in a preventive health panel can help identify an often-underdiagnosed condition early, before complications such as nutrient deficiencies or bone loss develop.

What It Measures

This test measures the level of IgA antibodies directed against tissue transglutaminase in your blood. It is the most sensitive and specific single blood test for coeliac disease screening. For accurate results you must be eating gluten regularly at the time of testing. The anti-TTG test measures transglutaminase IgA antibodies against tissue transglutaminase. It is used as a first-line screen; it does not provide a diagnosis of coeliac disease on its own and further evaluation by a healthcare provider is needed.

Why It Matters

Undiagnosed coeliac disease can lead to poor nutrient absorption, iron deficiency, osteoporosis and other problems. Early detection through anti-TTG screening allows for timely dietary management. A negative result in someone already on a gluten-free diet may be falsely reassuring. Because iron deficiency is a common sign, it can be helpful to view iron-related markers such as ferritin and iron (serum) alongside this test, and you can combine them in a custom blood test from the biomarkers overview.

When to Test

Consider testing if you have ongoing digestive symptoms such as bloating, diarrhoea or stomach pain after eating foods that contain gluten. Testing is also worth considering if coeliac disease runs in your family, if you have iron-deficiency anaemia of unknown cause, or if you have a related autoimmune condition. You must be eating gluten for at least 6 weeks before testing. To explore related markers you can browse the biomarkers overview or build a custom blood test.

Symptoms

Low Levels

Low or undetectable anti-TTG levels are within the normal range and suggest that coeliac disease is unlikely, provided you were consuming gluten at the time of testing and do not have IgA deficiency.

High Levels

Elevated anti-TTG levels may be associated with coeliac disease. Symptoms that often prompt testing include chronic bloating, diarrhoea, fatigue, weight loss, and iron-deficiency anaemia. However, elevated levels can occasionally occur in other conditions. Your healthcare provider will determine whether further investigation such as a duodenal biopsy is needed.

Lifestyle Tips

If coeliac disease is confirmed, a strict lifelong gluten-free diet is the primary treatment. Even small amounts of gluten can trigger immune activity. Work with a dietitian to ensure nutritional adequacy. Do not start a gluten-free diet before testing is complete, as this can produce falsely negative results.

Frequently Asked Questions

Can I test for coeliac disease if I am already gluten-free?
Anti-TTG levels may be falsely normal if you have been avoiding gluten. A gluten challenge of at least 6 weeks is typically required before testing for reliable results.
Is a positive anti-TTG result enough to diagnose coeliac disease?
In adults, a positive anti-TTG usually needs to be confirmed with a duodenal biopsy. In some cases with very high titres and positive endomysium antibodies, a no-biopsy diagnosis may be considered.
What if I have IgA deficiency?
IgA deficiency can cause a false-negative anti-TTG result. If IgA deficiency is known or suspected, an IgG-based coeliac test should be used instead.

Test Products

This marker is included in the following test panels.