Coeliac Disease
An immune reaction to dietary gluten that flattens the small-bowel villi, so the clinical picture is the predictable consequence of losing absorptive surface, and the treatment is simply removing the trigger.
In a nutshell
A gluten-driven, T-cell-mediated attack on the small-bowel mucosa that flattens the villi. Lose the absorptive surface and you get malabsorption, which is why coeliac disease so often presents as iron-deficiency anaemia or osteoporosis rather than diarrhoea. Removing the trigger reverses it.
Classic presentation
Chronic diarrhoea, bloating and weight loss, or just as often an iron-deficiency anaemia that will not respond to oral iron, sometimes with an intensely itchy vesicular rash on the extensor surfaces.
Key points
- Villous atrophy is the defining lesion. The proximal small bowel is worst affected, so iron, folate and calcium (absorbed there) are the deficiencies you see first.
- Test with anti-tissue transglutaminase IgA, and always send a total IgA alongside it: IgA deficiency gives a false-negative result.
- The patient must still be eating gluten when tested. Both the antibodies and the villous atrophy normalise off gluten, and the diagnosis is missed.
- Duodenal biopsy confirms villous atrophy before committing someone to a lifelong diet.
- Dermatitis herpetiformis is the cutaneous expression of the same immune process.
- A strict lifelong gluten-free diet removes the immune stimulus: the villi regrow and absorption recovers.
First-line investigation
Anti-tissue transglutaminase IgA with a total IgA, taken while the patient is still eating gluten.
First-line management
Confirm the diagnosis first, then a strict lifelong gluten-free diet with dietitian support, correcting iron, folate, calcium and vitamin D.
Exam traps
- If the patient has already excluded gluten, serology and biopsy can both be falsely normal. Gluten must be reintroduced before testing, not the result accepted.
- Selective IgA deficiency is over-represented in coeliac disease and makes anti-tTG IgA falsely negative. That is why total IgA is sent with it.
- Unexplained iron-deficiency anaemia or early osteoporosis should prompt coeliac serology even with no bowel symptoms at all.
Educational content pending clinical review. Not medical advice.