The ALT/AST Ratio as a Predictor of MASLD in Obese Children: A Comparative Analysis with Metabolic Indices Including HOMA-IR and TyG.

Background/Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD) is getting more prevalent in children with obesity, and simple and non-invasive biomarkers are needed for early detection. In this study, the discriminative performance of the ALT/AST ratio (AT index) for MASLD was evaluated in comparison with metabolic indices such as HOMA-IR and TyG derivatives. Methods: A total of 410 children with obesity aged 5-18 years were included in this prospective, multicenter cross-sectional study. Anthropometric measurements, laboratory data, and abdominal ultrasonography findings of the participants were evaluated. MASLD was diagnosed based on ultrasonographic findings. The discriminative performance of the indices was evaluated using ROC analysis, and factors independently associated with MASLD were assessed using multivariate logistic regression analysis. Results: BMI SDS, ALT, AT index, insulin, HOMA-IR, and TyG/ALT values were found to be significantly higher in the MASLD (+) group (p < 0.05). The AT index demonstrated statistically significant but modest discriminative ability for MASLD (AUC = 0.621; p < 0.001) and showed 70.5% sensitivity and 50.7% specificity at a cutoff value of >0.88. In the multivariate analysis, the AT index (OR: 3.401; 95% CI: 1.717-6.735; p < 0.001) and BMI SDS were identified as factors independently associated with MASLD.HOMA-IR and prolactin-related indices were not found to be significant as independent predictors. Conclusions: The ALT/AST ratio is a simple and accessible biomarker associated with MASLD in children with obesity. Although its discriminative performance is modest, its association with hepatic involvement and metabolic dysfunction suggests that it may provide supportive exploratory information in the evaluation of MASLD. However, further validation studies are required before broader clinical application.