What is the Tissue Transglutaminase IgG test?

The Tissue Transglutaminase IgG (tTG IgG) test measures IgG antibodies directed against tissue transglutaminase, an enzyme involved in maintaining the lining of the small intestine. In coeliac disease, exposure to gluten triggers an autoimmune response that damages intestinal tissue and leads to antibody production.

Unlike the tTG IgA test, this IgG-based test does not rely on normal IgA levels. It is therefore especially useful in individuals with IgA deficiency, where standard coeliac screening tests may give false-negative results.

This test is used as an alternative or complementary investigation when coeliac disease is suspected.

Why do I need a Tissue Transglutaminase IgG test?

Some people with coeliac disease cannot be reliably assessed using IgA-based tests due to IgA deficiency or atypical immune responses. In these cases, IgG antibodies provide important diagnostic insight.

You may need this test if you:

• Have symptoms suggestive of coeliac disease
• Have known or suspected IgA deficiency
• Have negative tTG IgA results but ongoing symptoms
• Experience chronic digestive issues or bloating
• Have unexplained fatigue or nutritional deficiencies
• Have iron deficiency or anaemia
• Have a family history of coeliac disease
• Have other autoimmune conditions

Testing helps avoid missed diagnoses when standard screening is insufficient.

Benefits of the test

1. Alternative coeliac screening option
   Useful when IgA-based testing is unreliable.
2. Suitable for IgA deficiency
   Detects immune response independent of IgA levels.
3. Supports diagnosis in complex cases
   Helps clarify unclear or conflicting results.
4. Detects autoimmune intestinal activity
   Identifies gluten-related immune response.
5. Simple blood-based testing
   Requires only a single blood sample.
6. Useful alongside other coeliac markers
   Complements tTG IgA and total IgA testing.
7. Supports early identification
   Helps reduce delayed diagnosis.
8. Applicable across age groups
   Used in adults and children when indicated.

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 IgG within reference range
• UK standard (typical): <7 U/mL
• Suggests no evidence of IgG-mediated coeliac autoimmunity

Borderline result

• Slightly raised antibody levels
• UK standard: 7–10 U/mL
• May reflect early disease or non-specific immune response

Positive (suggestive of coeliac disease)

• Elevated tTG IgG antibodies
• UK standard: >10 U/mL
• Supports diagnosis of coeliac disease, especially with compatible symptoms

Results should be interpreted alongside clinical findings and other coeliac-related tests.