The ratio of serum creatinine to Klotho (SCr/Kl) increased notably in AKI patients in the immediate postoperative period (0.99 ± 0.23 vs. 0.62 ± 0.15, p < 0.01) and offered superior AKI detection at a 0.695 cutoff, with 94.7% sensitivity, 87.5% specificity, and 92.4% AUC. Here, KL is linked to acute kidney injury.