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Coeliac disease
Coeliac disease is diagnosed with anti-tTG IgA together with total IgA — while the patient is still eating gluten — and confirmed with duodenal biopsies; treatment is a lifelong gluten-free diet.
Why it matters in the exam
Questions present not only diarrhoea and weight loss but mostly "silent" pictures: iron deficiency anaemia that does not respond to oral iron, osteoporosis at a young age, raised liver enzymes, infertility or an itchy blistering rash on the elbows and knees (dermatitis herpetiformis — almost diagnostic). The candidate must choose the right test: anti-tTG IgA together with total IgA, because in IgA deficiency (more common in coeliac disease) the test is falsely negative, and IgG-based tests are used instead. A standard distractor: a patient who has already stopped eating gluten — the tests and the biopsy may come back normal.
After positive serology, adults are confirmed by gastroscopy with at least 4 biopsies from the second part of the duodenum and 1–2 from the bulb: intraepithelial lymphocytes, crypt hyperplasia and villous atrophy. Associations worth remembering: type 1 diabetes, autoimmune thyroid disease, Down and Turner syndromes, IgA deficiency and first-degree relatives. Negative HLA-DQ2 and DQ8 almost exclude the disease. After diagnosis: a gluten-free diet, a dietitian's review, a bone density scan and nutritional deficiencies, and a repeat anti-tTG after 6–12 months. Symptoms that persist despite the diet call first for an adherence check, and only then for suspicion of refractory coeliac disease or lymphoma.
Key points
- Screening: anti-tTG IgA with total IgA, while eating gluten.
- Confirmation: at least 4 duodenal biopsies — villous atrophy.
- Refractory iron deficiency and osteoporosis in a young person — think coeliac.
- Risk groups: type 1 diabetes, thyroid, Down, Turner, relatives.
- Lifelong gluten-free diet and a repeat anti-tTG after 6–12 months.
Summary table
| Step | Test / finding | Action | Exam note |
|---|---|---|---|
| Screening | Anti-tTG IgA + total IgA | While eating gluten | In IgA deficiency — IgG tests |
| Adult confirmation | Gastroscopy: at least 4 duodenal biopsies and 1–2 from the bulb | Lymphocytes, crypt hyperplasia, villous atrophy | Before stopping gluten |
| "Silent" presentation | Refractory iron deficiency, osteoporosis, liver enzymes, infertility | Test for coeliac disease | Dermatitis herpetiformis is almost diagnostic |
| Risk groups | Type 1 diabetes, autoimmune thyroid, Down, Turner, first-degree relatives | Screening | Negative HLA-DQ2/DQ8 almost excludes |
| Treatment and follow-up | Gluten-free diet | Repeat anti-tTG after 6–12 months, bone density | Check adherence before suspecting refractoriness |
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Sources
- ACG Clinical Guidelines: Diagnosis and Management of Celiac Disease, 2023 — Serology, biopsy, gluten-free diet and follow-up
- European Society for the Study of Coeliac Disease (ESsCD) guideline for coeliac disease and other gluten-related disorders, 2019 — Diagnosis in adults
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Disorders of Absorption: Celiac Disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.