SOD1 and acute kidney injury: Furthermore, urinary SOD concentrations increased progressively with each stage of AKI (stage 1: 69.5 ng/ml ± 11.2 ng/ml, n = 158 VS stage 2: 132 ng/ml ± 92.1 ng/ml, n = 23 VS stage 3 AKI 986.8 ± 267.9 ng/ml, n = 20, p < 0.001 for Stage 3 compared to Stage 1 AKI) (Fig. 3).