Gluten Intolerance & Coeliac Disease Testing
Understanding Coeliac Disease and Gluten Sensitivity
Coeliac disease is an immune‑mediated condition in which the body reacts abnormally to gluten — a protein found in wheat, barley, and rye. In genetically susceptible individuals, gluten triggers inflammation and damage in the small intestine, leading to symptoms such as bloating, diarrhoea, abdominal pain, fatigue, and nutrient deficiencies.
Most people with coeliac disease carry specific immune‑system genes called HLA‑DQ2 or HLA‑DQ8. A negative result for both genes makes coeliac disease very unlikely (negative predictive value >99%). However, carrying these genes is not enough to cause the condition — many people have them but never develop coeliac disease. Other factors, including immune triggers and epigenetic influences, may contribute to when the condition appears.
Testing Available at the London Allergy and Immunology Centre
We provide a comprehensive assessment for gluten‑related disorders, including both antibody testing and genetic testing.
1. Coeliac Antibody Testing
Current international guidelines recommend the following tests:
- Tissue transglutaminase (tTG) IgA – first‑line screening test
- Endomysial antibodies (EMA) – confirmatory test
- Deamidated gliadin peptide (DGP) IgG – useful in IgA deficiency
- Total IgA level – to ensure accurate interpretation of results
These tests are most reliable when the patient is regularly consuming gluten. Antibody levels typically fall after starting a gluten‑free diet, which can make diagnosis more difficult.
2. Genetic Testing (HLA‑DQ2 / HLA‑DQ8)
Genetic testing is helpful when:
- A patient has already removed gluten from their diet
- Antibody tests are inconclusive
- There is a strong family history of coeliac disease
A negative result effectively rules out coeliac disease.
When to Seek Specialist Advice
If symptoms continue after 3 months on a strict gluten‑free diet, a consultation with a gastroenterologist is recommended to assess for coeliac disease complications or other gastrointestinal conditions.
Where Gluten Is Found
Gluten is naturally present in:
- Wheat (including spelt, kamut, triticale)
- Barley
- Rye
What About Oats?
Oats do not contain gluten. They contain avenins, which are tolerated by most people with coeliac disease. However:
- A small minority react to avenins
- Many standard oats are contaminated with wheat, barley, or rye during processing
Patients with coeliac disease should choose certified gluten‑free oats.
Intolerance or a milk allergy? Click here!
References
Coeliac UK – What Is Coeliac Disease? https://www.coeliac.org.uk/information-and-support/coeliac-disease/ (coeliac.org.uk in Bing)
NICE Guideline NG20 – Coeliac Disease: Recognition, Assessment and Management https://www.nice.org.uk/guidance/ng20
British Society of Gastroenterology (BSG) Guidelines on Coeliac Disease https://www.bsg.org.uk/clinical-resource/coeliac-disease/ (bsg.org.uk in Bing)
Last reviewed: February 2026