Clinical presentation, anti-tTG IgA levels, and histological severity in adult celiac disease

<jats:sec> <jats:title>Background</jats:title> <jats:p>Adult celiac disease may present with atypical or nonspecific symptoms. Although the diagnostic value of anti-tissue transglutaminase IgA (anti-tTG IgA) in relation to histological severity has been well-established in pediatric cases, data in adults remain limited.</jats:p> </jats:sec> <jats:sec> <jats:title>Objective</jats:title> <jats:p>To evaluate the association between anti-tTG IgA levels and histological severity according to the Marsh-Oberhuber classification in adult celiac patients, and to assess the diagnostic performance of anti-tTG IgA in predicting advanced mucosal damage.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>A total of 228 adult patients with celiac disease who underwent duodenal biopsy between 2017 and 2022 were included retrospectively. Clinical features, laboratory parameters, serological markers, histopathological findings were recorded. Patients were classified according to anti-tTG IgA titers as high-titer (≥10 times the upper limit of normal) or low-titer positive.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p> Anti-tTG IgA levels showed a significant stepwise increase with higher Marsh grades. Anti-tTG IgA levels and disease duration were independent predictors of Marsh score. Higher anti-tTG IgA levels were associated with an increased likelihood of advanced histological damage, whereas longer disease duration was associated with lower Marsh scores. Receiver operating characteristic curve analysis demonstrated diagnostic performance of anti-tTG IgA for predicting Marsh score greater than or equal to 2 (area under the curve = 0.836, 95% confidence interval: 0.781–0.883; <jats:italic toggle="yes">P</jats:italic> &lt; 0.0001). A cutoff value of less than 93.2 RU/ml yielded a sensitivity of 76.73% and a specificity of 83.33%. </jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion</jats:title> <jats:p>Anti-tTG IgA is associated with histological severity in adult celiac disease and demonstrate diagnostic accuracy for predicting clinically significant mucosal damage. We suggest that anti-tTG IgA may serve as a useful adjunctive marker for estimating histological involvement in adults.</jats:p> </jats:sec>