In a young woman with intermittent diarrhea and iron deficiency anemia, which laboratory test is most appropriate to evaluate for celiac disease?

• A. Anti-tTG
• B. Antigliadin
• C. Antigluten
• D. All of the above

Answer: (A)

Screening for celiac disease starts with serology when the clinical picture suggests malabsorption. The best single test is IgA against tissue transglutaminase because it has the highest sensitivity and specificity for detecting celiac disease. A positive anti-tTG result in a patient with chronic diarrhea and iron deficiency anemia strongly supports the diagnosis and typically leads to confirmatory evaluation with duodenal biopsy to assess intestinal damage.

Antigliadin antibodies were used in the past but are much less reliable today; they have more false positives and negatives and are not preferred for screening. There isn’t a standard test called antigluten, and the option that combines all tests isn’t appropriate because antigliadin is not as dependable as anti-tTG. Remember also that if someone has low IgA overall (IgA deficiency), IgA-based tests can be falsely negative, so total IgA should be checked and IgG-based tests considered if needed.