IGFBP7 and acute kidney injury: Compared to renin levels, [TIMP-2] × [IGFBP7] or urinary DKK3, the changes between pre-and postoperative renin levels (Δ-renin) performed best in predicting postoperative AKI with an AUC of 0.817 (95% CI, 0.747–0.887) [15].