LCN2 and acute kidney injury: In the ROC analysis, the combined SDC1-SOFA model achieved the highest AUC values for both AKI evaluation (AUC: 0.770; 95% CI: 0.692–0.849) and RRT initiation (AUC: 0.737; 95% CI: 0.635–0.838), outperforming individual biomarkers, including SDC1 alone (AUC: 0.659 for AKI, 0.715 for RRT), NGAL (AUC: 0.666 for AKI), PENK (AUC: 0.600 for AKI), and PSPN (AUC: 0.588 for AKI), across all evaluated endpoints.