A 38-year-old woman presents with iron deficiency anemia, bloating, and diarrhea. Endoscopy shows normal gastric mucosa and duodenal biopsies reveal villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes. Serology shows anti-tTG IgA antibody 98 U/mL (normal <7). IgA level is normal. The MOST sensitive and specific serological test for celiac disease is:
- A Anti-tissue transglutaminase (tTG) IgA antibody ✓
- B Anti-gliadin IgA antibody
- C Anti-endomysial IgA antibody (EMA)
- D Anti-deamidated gliadin peptide (DGP) IgG
Correct answer: A. Anti-tissue transglutaminase (tTG) IgA antibody
Explanation
Anti-tTG IgA is the most sensitive (95–99%) and specific (95–99%) serological test for celiac disease and is recommended as the initial screening test by current ESPGHAN/ACG guidelines. Anti-EMA IgA has similar specificity but lower sensitivity (90–95%) and is operator-dependent. Anti-gliadin antibodies (AGA) have poor specificity and have been replaced. Anti-DGP IgG is useful when IgA deficiency is present (which should be tested when tTG IgA is low despite high suspicion).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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