A 26-year-old woman with chronic diarrhea and iron deficiency anemia has a serum total IgA level below the assay detection limit. Her anti-tissue transglutaminase IgA test is reported negative. Which serological approach is most appropriate to evaluate her for celiac disease?
- A Test anti-tTG IgG or deamidated gliadin peptide IgG antibodies ✓
- B Repeat anti-tTG IgA after three months on a gluten-containing diet
- C Measure anti-endomysial IgA antibodies instead
- D Serological testing is uninterpretable and biopsy must be avoided
Correct answer: A. Test anti-tTG IgG or deamidated gliadin peptide IgG antibodies
Explanation
About 2 to 3 percent of celiac patients have selective IgA deficiency, which makes IgA-based tests falsely negative. In such patients, IgG-class assays, either anti-tTG IgG or deamidated gliadin peptide IgG, retain good sensitivity and specificity and guide the decision for duodenal biopsy. Anti-endomysial IgA suffers the same limitation as tTG IgA, and biopsy remains feasible and is interpreted alongside the IgG serology.
Reference: Williams Textbook of Endocrinology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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