KLK1 promoter methylation in blood DNA was higher in AKI than controls (70.32 ± 2.27 vs. 65.36 ± 1.05%; p = 0.011), and there was also a trend towards higher urine KLK1 methylation in AKI than controls, but the difference was not significant (40.95 ± 7.06 vs. 30.35 ± 5.88%; p = 0.22). Here, KLK1 is linked to acute kidney injury.