Futhermore, the level of NGAL protein and creatinine were further monitored with the urine of 4 AKI patients during the acute and recovery phases (Fig. 7c), and we found that the level of NGAL protein in the later phase was significantly lower than its level in the acute phase, which is also consistent with the tendency of creatinine, suggesting that the level of NGAL protein could be used to monitor the status of recovery stage of patients with AKI. This evidence concerns the gene LCN2 and acute kidney injury.