Acute kidney injury (AKI) is a common heterogeneous disease that complicates several medical and surgical conditions. Recent studies have demonstrated that the occurrence of AKI significantly increase the risk of adverse outcomes. Despite the advanced in modern medicine, the interventions for AKI are not improved. One major reason of the failure to shift therapeutic progress is the clinicians' widespread dependence upon serum creatinine, an unreliable marker during acute changes of renal function, for the diagnosis of AKI.