Neutrophil gelatinase-associated lipocalin (NGAL) for the early detection of cardiac surgery associated acute kidney injury

BACKGROUND: Acute kidney injury (AKI) is a common complication after cardiac surgery. Neutrophil gelatinase-associated lipocalin (NGAL) may be an early biomarker for cardiac surgery-associated (CSA) AKI. We investigated whether increased urinary NGAL concentrations were predictive of AKI within 4 days after surgery and of mortality within 9 months. METHODS: Consecutive patients (n = 141) undergoing major cardiac surgery were included. Creatinine, blood urea nitrogen, cystatin C and urinary NGAL were measured before, 4 hours and 4 days after extracorporeal circulation. RESULTS: AKI was observed in 47 (33.3%) patients. The 4-hour urinary NGAL measurement was an independent predictor of stage 2 and 3 AKI (AUC 0.901; 95% CI 0.81-0.99). Patients with AKI had a higher 9-month mortality rate (19.1% vs. 3.2%; logrank 10.9; P = 0.001; HR 19.8; 95% CI 3.7-107.1). Urinary NGAL was not predictive of mortality within 9 months after surgery. CONCLUSION: Urinary NGAL is a biomarker for very early risk stratification of AKI after cardiac surgery and may be useful as a basis for early interventional strategies to prevent CSA-AKI.