In adults with suspected celiac disease, what is the single preferred serologic test?

• A. Anti-endomysial antibody
• B. Anti-tissue transglutaminase (tTG) IgA antibody
• C. Anti-gliadin antibodies
• D. Tissue transglutaminase (tTG) IgA antibody

Answer: (D)

Tissue transglutaminase IgA antibodies are the best first-choice serologic test for adults with suspected celiac disease. This assay combines high sensitivity and high specificity, is widely standardized and cost-effective, and works well as a screening tool in clinical practice. Anti-gliadin antibodies are older and less reliable due to poor specificity, and anti-endomysial antibodies, while highly specific, require more manual testing and are less practical for routine screening. If the patient has IgA deficiency, the IgA-based result can be falsely negative, so checking total IgA and using an appropriate IgG-based test is important. A positive tTG IgA test typically leads to confirmatory evaluation with further diagnostic steps such as biopsy, depending on guidelines.