Acute kidney injury (AKI) is one of the most common complications of various serious
conditions, and early diagnosis is therefore critical for the treatment of AKI. Increase of the classic
AKI biochemical markers such as serum creatinine is not evident until renal function is irreversibly
damaged, which adds to the difficulties of early identification of AKI and results in an increase of the
mortality rate. In order to improve the prevention, diagnosis, treatment, and prognosis prediction of
AKI, novel early markers of AKI are required. Recent evidence demonstrates that neutrophil gelatinase-
associated lipocalin (NGAL) is closely associated with AKI. Several experimental and clinical
studies have shown that the expression of urine and serum NGAL increases significantly in AKI.
In particular, the urine NGAL level is closely associated with the severity of kidney injury, and could
be detected earlier than other AKI markers. Therefore, NGAL shows potential to be a new effective
early biochemical marker of AKI. Further studies are needed to confirm the significant advantages of
NGAL in the diagnosis of early AKI and its value in clinical applications.