Celiac Disease Diagnosis
A 28-year-old woman has had chronic diarrhea, bloating, and 6 kg weight loss for one year. Hemoglobin is 9.8 g/dL with ferritin 6 µg/L despite oral iron. Anti-tissue transglutaminase IgA is strongly positive with normal total IgA. She continues a normal gluten-containing diet. Which statement about establishing her diagnosis is correct?
- A.Symptom resolution on a gluten-free diet alone establishes the diagnosis
- B.Duodenal biopsy has no role once serology has been requested
- C.Celiac disease is excluded because she presented in adulthood
- D.Positive serology should be confirmed by duodenal biopsy showing villous atrophyCorrect
Explanation
In adults, the diagnosis of celiac disease rests on positive serology followed by confirmatory duodenal biopsy taken while the patient is still eating gluten. Anti-tissue transglutaminase IgA is the recommended first-line test, with total IgA measured at the same time because selective IgA deficiency is over ten times more common in celiac disease and produces false negative results. Serology is sensitive and specific but not perfect: false positives occur with other autoimmune disease, chronic liver disease and heart failure, so a lifelong dietary commitment should not be started on a blood test alone in adults. Endoscopy with at least four distal duodenal and one or two bulb biopsies demonstrates intraepithelial lymphocytosis, crypt hyperplasia and villous atrophy, and also excludes mimics such as tropical sprue, giardiasis and small intestinal bacterial overgrowth. The gluten-containing diet must be maintained until biopsy, otherwise the mucosa heals and the histology becomes non-diagnostic. Selected paediatric patients can avoid biopsy when tissue transglutaminase IgA exceeds ten times the upper limit of normal with a positive endomysial antibody, but this no-biopsy pathway is not the default in adults. Celiac disease is common in adults, and iron deficiency anaemia refractory to oral iron is one of its most frequent presentations. Symptomatic improvement on a gluten-free diet is non-specific because irritable bowel syndrome and non-celiac gluten sensitivity also improve.
Why each option
- A.
- A response to gluten withdrawal is non-specific and also occurs in irritable bowel syndrome and non-celiac gluten sensitivity, so it cannot establish the diagnosis.
- B.
- Biopsy remains the diagnostic standard in adults; serology alone can be falsely positive in other autoimmune and inflammatory conditions.
- C.
- Celiac disease frequently presents for the first time in adults, often with anaemia, osteoporosis or deranged liver enzymes rather than diarrhoea.
- D.
- Correct. Serology screens and duodenal histology confirms; biopsy must be taken while the patient is still consuming gluten to avoid a falsely normal mucosa.
Reference: American College of Gastroenterology Clinical Guideline: Diagnosis and Management of Celiac Disease, 2023
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