Evidence check: tTG IgA in the context of Haut

tTG IgA (tissue transglutaminase IgA) is a well-established serological marker for celiac disease. In the context of skin, the strongest link is with dermatitis herpetiformis (Duhring's disease), a gluten-sensitive skin condition where tTG IgA is often elevated. Evidence for this association is human-strong (multiple studies, guidelines). However, tTG IgA is not a direct skin test; it is measured in blood. For non-specific skin issues (e.g., eczema, acne) without celiac suspicion, its utility is unclear – many direct-to-consumer tests market tTG IgA as a 'gluten sensitivity marker', but evidence for non-celiac gluten sensitivity is weak. Caveat: A positive tTG IgA result always requires gastroenterological follow-up (duodenal biopsy). For skin symptoms, additional skin biopsy for IgA deposits is recommended. Testing without clinical indication may lead to misinterpretation.