Evidence check: tTG IgA in the context of Sport

tTG IgA (tissue transglutaminase IgA) is a well-established serological marker for celiac disease. In the context of sport, it is occasionally measured in athletes with unexplained gastrointestinal symptoms, fatigue, or performance decline. However, evidence for routine screening in asymptomatic athletes is weak. Celiac disease affects about 1% of the population, and undiagnosed cases can impair athletic performance due to malabsorption of iron, vitamin D, and B12. Yet tTG IgA is not a direct performance or recovery biomarker. A positive test requires gastroenterological follow-up with duodenal biopsy. False positives can occur, especially in IgA deficiency or other autoimmune conditions. Testing should be reserved for clinical suspicion, not as a general sports screening. Evidence is based on clinical practice and guidelines, not on specific sport studies. Caveat: A negative test does not rule out celiac disease, particularly in IgA deficiency (then IgG-based tests are needed).