Synopsis
Recognise the broad adult coeliac phenotype, preserve gluten exposure for valid testing, apply the current 2026 BSG biopsy or selected no-biopsy pathway, and manage lifelong gluten exclusion, deficiencies and non-response safely.
- Coeliac disease is an immune-mediated enteropathy triggered by gluten in genetically susceptible people; presentation ranges from diarrhoea and weight loss to isolated iron deficiency, osteoporosis, neuropathy or abnormal liver tests.
- Test while the person eats gluten in more than one meal daily for at least six weeks where possible, and advise against starting a gluten-free diet before specialist diagnosis.
- First-line adult serology is total IgA plus IgA tissue transglutaminase; use EMA for appropriate equivocal results and IgG-based testing when IgA deficient.
- Positive serology warrants gastroenterology assessment. The 2026 BSG guideline permits a no-biopsy diagnosis only in a selected secondary-care subgroup, not as a universal shortcut.
- If biopsy is required, obtain sufficient samples from duodenal bulb and distal duodenum because changes are patchy and orientation affects interpretation.
- Treatment is a lifelong strict gluten-free diet taught by a specialist dietitian, with practical attention to cross-contact, labels, eating out and adequate fibre and micronutrients.
- Assess iron, folate, B12, vitamin D, calcium, weight and bone risk at diagnosis; correct measured deficits and consider hyposplenism and vaccination through the current pathway.
- Persistent symptoms demand diagnostic review: inadvertent gluten, IBS, lactose intolerance, microscopic colitis, pancreatic insufficiency and rare refractory coeliac disease are not interchangeable.
Key red flags
Profuse diarrhoea, dehydration, major electrolyte disturbance, hypoalbuminaemia or rapid wasting is rare but needs admission, nutrition support and specialist exclusion of infection or refractory disease.
Persistent malabsorption and villous atrophy despite verified strict diet raises ongoing gluten, wrong diagnosis, refractory coeliac disease, ulcerative jejunitis or lymphoma and warrants an expert centre.
Investigation priorities
Screen symptomatic or at-risk adults while consuming gluten and identify IgA deficiency that changes assay choice.
Management branches
Coeliac disease is suspected from symptoms, deficiency or risk group.
- Confirm adequate gluten exposure and order total IgA with IgA tTG, using alternative assays when IgA deficient.
- Refer positive or strongly suspected cases to gastroenterology without advising gluten exclusion; address severe dehydration or malnutrition immediately.
- Apply the live 2026 BSG secondary-care criteria for selected no-biopsy diagnosis or undertake correctly sampled duodenal histology.
- Document the evidence supporting diagnosis before prescribing a lifelong restrictive diet.