KLK4 and acute kidney injury: To exclude the possibility that diuretic treatment at study entry increased urinary kallikrein excretion [20], we conducted statistical analysis again by exclusion of the 3 diuretic cases (Tables 1); urinary kallikrein excretion remained significantly different between AKI and controls (urine kallikrein/urine creatinine ratio: 7.14 ± 2.18 vs. 0.63 ± 0.08 mU/mg; p = 0.001).