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Gastroenterology & Nutrition

Coeliac Disease

An immune-mediated response to dietary gluten that injures the small-bowel mucosa and causes gastrointestinal or extraintestinal disease; confirm it while gluten is being eaten before starting a lifelong gluten-free diet.

In a nutshell

Coeliac disease is an immune-mediated gluten-triggered enteropathy. Test with IgA-tTG plus total IgA while gluten is being eaten, confirm through the appropriate specialist pathway, then treat with a strict lifelong gluten-free diet, dietitian support, deficiency and bone assessment, and structured follow-up.

Classic presentation

Persistent diarrhoea, bloating or weight loss, or an extraintestinal clue such as unexplained iron-deficiency anaemia, fatigue, mouth ulcers, metabolic bone disease, type 1 diabetes or dermatitis herpetiformis.

Key points

  • Think beyond diarrhoea: unexplained iron-, B12- or folate-deficiency anaemia, fatigue, bone disease, neurological symptoms, subfertility, type 1 diabetes, autoimmune thyroid disease and an affected first-degree relative are recognised testing prompts.
  • First-line blood tests are IgA-tTG with total IgA; use IgG-based coeliac serology if IgA deficient and EMA for a weakly positive tTG according to the laboratory pathway.
  • Keep eating gluten during diagnosis. If gluten has already been restricted, use the specialist gluten-challenge pathway rather than accepting a negative test off gluten.
  • Do not start a gluten-free diet before specialist confirmation, even after positive serology, unless a specialist has selected the adult no-biopsy pathway.
  • For symptomatic adults in secondary care, the 2026 BSG guideline allows an optional no-biopsy diagnosis when IgA-tTG is at least 10 times the assay upper limit of normal, with local validation, no red flags or competing endoscopy indication and shared decision-making.
  • After confirmation, use a strict lifelong gluten-free diet with specialist dietitian support; symptom improvement alone does not prove coeliac disease.
  • Check iron, folate, B12, vitamin D, calcium and bone health; tTG alone does not prove dietary adherence or mucosal healing.
  • Use the current Green Book pneumococcal pathway: additional vaccination is for coeliac disease with evidence of splenic dysfunction, with local specialist assessment where risk is uncertain.

First-line investigation

IgA tissue transglutaminase with total IgA while eating gluten; use IgG-based tests if IgA deficient and refer positive or persistently suspicious cases to gastroenterology.

Management

Case-find and protect the diagnostic pathway

  • Test people with gastrointestinal or extraintestinal features and high-risk associations; keep gluten in the diet and do not start a gluten-free diet before specialist confirmation.1,3

Use coeliac serology correctly

  • Send IgA-tTG with total IgA, then use EMA for weakly positive tTG or IgG-based serology for IgA deficiency according to the laboratory pathway.1,2
  • If gluten has already been restricted, discuss a 3–6 g daily gluten challenge for at least 6 weeks with specialist support; do not improvise a diagnosis from a negative test off gluten.1,2,4

Confirm through gastroenterology

  • Refer positive serology and persistent clinical suspicion to gastroenterology. Adults may have biopsy or the optional validated BSG no-biopsy pathway when IgA-tTG is at least 10 times the upper limit of normal and the specialist confirms suitability.1,2,4

Treat the confirmed disease

  • Start a strict lifelong gluten-free diet with specialist dietitian support and signpost reliable coeliac-disease information; discuss gluten-free oats with follow-up rather than presenting them as an automatic exclusion.1,5,2
  • Assess and correct iron, folate, B12, vitamin D and calcium deficiency and assess bone health; the adult BSG guideline advises DXA one year after starting the diet.1,2,3

Use the current vaccine and complication pathway

  • Assess splenic function and follow the current Green Book pneumococcal schedule when splenic dysfunction is present; the national vaccine pathway is the normative source for eligibility.8,5

Review response and escalate non-response

  • Offer annual NICE review and regular specialist or dietetic follow-up for up to 2 years after diagnosis; combine symptoms, dietetic assessment and investigations because tTG alone does not assess mucosal healing.1,6,2
  • Persistent symptoms require a diagnosis check, specialist dietitian assessment for gluten exposure and investigation of coexisting disease; suspected refractory coeliac disease needs specialist-centre multidisciplinary care.1,5,2

Exam traps

  • A negative coeliac blood test after gluten restriction is not reassuring: testing requires adequate gluten exposure, and ongoing suspicion needs specialist assessment.
  • Total IgA matters because selective IgA deficiency can make IgA-tTG falsely negative; use IgG-based serology when appropriate.
  • Do not diagnose coeliac disease from symptom improvement on a gluten-free diet alone and do not start the diet before specialist confirmation.
  • The adult no-biopsy pathway is a specialist, optional BSG pathway for selected symptomatic adults; it is not a primary-care shortcut and does not replace paediatric guidance.
  • Serology is not a stand-alone test of mucosal healing or complete gluten exclusion after diagnosis.
  • Do not automatically offer pneumococcal vaccination to every person with coeliac disease: follow the current Green Book rule and assess splenic dysfunction.

Illustrations

Villous atrophy on duodenal biopsyDuodenal biopsy histology showing villous blunting, crypt hyperplasia and inflammatory cells associated with coeliac disease.Samir at English Wikipedia, Wikimedia Commons · CC-BY-SA-3.0
Dermatitis herpetiformisClinical photograph of the symmetrical, intensely itchy vesicular rash associated with coeliac disease.BallenaBlanca, Wikimedia Commons · CC-BY-SA-3.0
Duodenal scalloping in coeliac diseaseEndoscopic view of the second part of the duodenum showing scalloped or fissured folds that may suggest villous injury.Abhinav Vasudevan and John S Lubel, Wikimedia Commons · CC-BY-4.0

Key sources

  1. NICE NG20, Coeliac disease: recognition, assessment and management — recommendationsUpdated 2 Sept 2015
  2. British Society of Gastroenterology, 2026 guidelines on diagnosis and management of adult coeliac diseaseUpdated 20 Apr 2026
  3. NHS, coeliac disease — diagnosisUpdated 31 Mar 2023
  4. Coeliac UK, BSG guideline on diagnosis and management of adult coeliac disease — highlights
  5. NHS, coeliac disease — treatmentUpdated 31 Mar 2023
  6. Coeliac UK, follow up after diagnosis
  7. NICE QS134, Coeliac disease — quality statement 3: endoscopic intestinal biopsyUpdated 1 Nov 2022
  8. UK Health Security Agency, pneumococcal vaccination for older adults and clinical risk groupsUpdated 13 Apr 2026

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.