Table 2 presents the prognostic accuracy of each parameter using the optimal cut-off values obtained by Youden’s index (J = sensitivity + specificity—1). NGAL (56.4 μg/mg creatinine; J = 0.360) revealed 82.6% sensitivity, 53.3% specificity, 16.7% positive predictive value (PPV), and 96.5% negative predictive value (NPV). In the subgroup of patients without CKD, the predictors NGAL-, KIM-1- and calprotectin/creatinine failed to reach individual significance in the regression analysis, the multivariable model yielded an AUC of 0.62 (95% CI 0.46–0.77; S1 Table). This evidence concerns the gene LCN2 and chronic kidney disease.