CST3 and acute kidney injury: The specific objectives are to: 1) evaluate the predictive value of the APACHE II score, RDW, and additional serum markers such as PCT, IL-6, CRP, and cystatin C for the development of AKI in children with sepsis; 2) establish a comprehensive risk scoring model incorporating these markers; and 3) assess the predictive performance and clinical applicability of the model in a pediatric ICU setting.