What is the Tissue Transglutaminase IgA test?

The Tissue Transglutaminase IgA (tTG IgA) test measures IgA antibodies produced by the immune system in response to tissue transglutaminase, an enzyme involved in intestinal tissue repair. In coeliac disease, ingestion of gluten triggers an autoimmune reaction that damages the lining of the small intestine.

Elevated tTG IgA antibodies are strongly associated with coeliac disease and reflect active immune-mediated intestinal inflammation. This test is widely recommended as the first-line blood test for coeliac screening.

For accurate results, the test should be performed while gluten is still included in the diet.

Why do I need a Tissue Transglutaminase IgA test?

Coeliac disease can present with a wide range of digestive and non-digestive symptoms, and some individuals have minimal or no gastrointestinal complaints.

You may need this test if you experience:

• Chronic diarrhoea or constipation
• Bloating, gas, or abdominal discomfort
• Unexplained weight loss
• Fatigue or low energy
• Iron deficiency or anaemia
• Vitamin or mineral deficiencies
• Skin rashes (such as dermatitis herpetiformis)
• Family history of coeliac disease
• Other autoimmune conditions

Identifying coeliac disease early helps prevent long-term complications such as malabsorption and nutritional deficiencies.

Benefits of the test

1. Primary screening test for coeliac disease
   Most sensitive and specific blood test for coeliac screening.
2. Detects autoimmune intestinal damage
   Identifies immune response triggered by gluten.
3. Explains non-specific symptoms
   Useful when symptoms are vague or extra-intestinal.
4. Guides further investigation
   Positive results support referral for confirmatory testing.
5. Simple blood-based testing
   Requires only a blood sample.
6. Useful in adults and children
   Widely used across age groups.
7. Supports early diagnosis
   Early detection helps prevent long-term complications.
8. Reduces diagnostic delay
   Helps avoid prolonged unexplained symptoms.

Step-by-step: How we offer testing

Clinic-based testing (UK-wide)

• Choose your nearest UK clinic
• Attend your appointment
• A clinician draws a blood sample
• Sample is sent to the laboratory
• Results are issued once analysis is complete

Home or hotel visit (+£60, UK-wide)

• Book a mobile phlebotomist
• Blood sample taken at your home or hotel
• No need to attend a clinic
• Sample securely transported to the laboratory

Your results explained

Negative (unlikely coeliac disease)

• tTG IgA within reference range
• UK standard (typical): <7 U/mL
• Suggests no evidence of active coeliac disease

Borderline or mildly positive

• tTG IgA slightly above reference range
• UK standard: 7–10 U/mL
• May suggest early or mild disease

Positive (suggestive of coeliac disease)

• Significantly elevated tTG IgA
• UK standard: >10 U/mL
• Strongly supportive of coeliac disease

Total IgA levels may be checked separately if IgA deficiency is suspected.