Which antibody is commonly tested for in suspected celiac disease?

Which antibody is commonly tested for in suspected celiac disease?

• A. Anti-Gliadin IgA
• B. Anti-Endomysial IgA
• C. Anti-Desmoglein IgA
• D. Anti-Tissue Transglutaminase IgA

Answer: (D)

In suspected celiac disease, the first-line serologic test is an antibody against tissue transglutaminase, specifically the IgA class. This antibody is the most useful screening marker because it provides a high balance of sensitivity and specificity, is widely available, and yields consistent results across laboratories. A positive anti-tTG IgA test strongly supports gluten-driven intestinal injury and often prompts further evaluation, such as endoscopic biopsy, to confirm the diagnosis. Older anti-gliadin IgA testing is less reliable because its sensitivity and specificity are lower, leading to more false positives and negatives. Anti-endomysial IgA is highly specific, but it requires expert interpretation of indirect immunofluorescence and is more labor-intensive, which is why it’s not the preferred first-line screen today. Anti-desmoglein IgA is associated with pemphigus and has no relevance to celiac disease, so it isn’t used in this context. One caveat to keep in mind is IgA deficiency, which can cause false-negative results with IgA-based tests. In such cases, total IgA levels should be checked, and if deficiency is present, alternative testing with IgG-based antibodies (for example, IgG against deamidated gliadin peptides or tTG) is used.

In suspected celiac disease, the first-line serologic test is an antibody against tissue transglutaminase, specifically the IgA class. This antibody is the most useful screening marker because it provides a high balance of sensitivity and specificity, is widely available, and yields consistent results across laboratories. A positive anti-tTG IgA test strongly supports gluten-driven intestinal injury and often prompts further evaluation, such as endoscopic biopsy, to confirm the diagnosis.

Older anti-gliadin IgA testing is less reliable because its sensitivity and specificity are lower, leading to more false positives and negatives. Anti-endomysial IgA is highly specific, but it requires expert interpretation of indirect immunofluorescence and is more labor-intensive, which is why it’s not the preferred first-line screen today. Anti-desmoglein IgA is associated with pemphigus and has no relevance to celiac disease, so it isn’t used in this context.

One caveat to keep in mind is IgA deficiency, which can cause false-negative results with IgA-based tests. In such cases, total IgA levels should be checked, and if deficiency is present, alternative testing with IgG-based antibodies (for example, IgG against deamidated gliadin peptides or tTG) is used.