This prospective, single-center, two-group observational study evaluates a non-invasive multi-parameter diagnostic panel for metabolic dysfunction-associated steatotic liver disease (MASLD) in children with obesity. A total of 180 children aged 8 to 18 years with a body mass index at or above the 85th percentile for age and sex are planned for enrollment at a single tertiary pediatric center.

Each participant attends a single study visit comprising a fasting venous blood sample for serum biomarkers (cytokeratin-18 M30 and M65, fibroblast growth factor 21, retinol-binding protein 4, insulin-like growth factor binding protein 7, adiponectin, leptin, insulin, and routine biochemistry), abdominal ultrasonography with two-dimensional shear wave elastography, and genotyping of three MASLD-associated variants (PNPLA3 rs738409, TM6SF2 rs58542926, HSD17B13 rs72613567).

Participants are classified as MASLD-positive or MASLD-negative according to a guideline-based composite reference standard consisting of ultrasonographic steatosis grading and cardiometabolic risk factor criteria, assessed independently of the candidate index tests. The primary objective is to determine the discriminative performance, expressed as the area under the receiver operating characteristic curve, of a LASSO-regularized logistic regression model combining biomarker, elastography, and genetic predictors. No therapeutic intervention is assigned by the study protocol. Reporting will follow the STARD 2015 statement.