What to watch with tTG IgA and Sport?

The tTG IgA test (tissue transglutaminase IgA) is a well-established serological biomarker for celiac disease, not directly for sports performance. In athletes, undiagnosed celiac disease can impair performance due to malabsorption, iron deficiency, fatigue, and reduced endurance. A positive tTG IgA requires gastroenterological follow-up with duodenal biopsy for confirmation. Importantly, this is an antibody test, not a genetic test (like HLA-DQ2/DQ8). False positives can occur in other autoimmune conditions or infections. For asymptomatic athletes, routine screening is not recommended. If celiac is suspected, gluten must be consumed before testing. Evidence for clinical use is strong (guidelines), but the link to sports is indirect via the disease. Caveat: negative tTG IgA does not rule out celiac disease if IgA deficiency is present.