CST3 and acute kidney injury: In addition, the predictive capacity of preoperative Cystatin C for AKI stage 2/3, AKI with need for RRT and 30-d-mortality was very strong (AKI 2–3: AUC 0.933, p < 0.001, RRT: AUC 0.919, p < 0.001; 30-d-mortality: AUC 0.887, p < 0.001).