Neutrophil Gelatinase-Associated Lipocalin and Contrast-Induced Acute Kidney Injury.

Background--Neutrophil gelatinase-associated lipocalin (NGAL) is an early marker of acute kidney injury (AKI). Methods and Results--Urine NGAL and serum NGAL (sNGAL) were assessed at 2, 6, 24, and 48 hours after contrast media (CM) exposure in 458 high-risk patients (development set). Optimal thresholds in predicting contrast-induced AKI (serum creatinine [sCr] increase >=0.3 mg/dL at 48 hours after CM administration) were identified. Major adverse events (MAE; death, dialysis, nonfatal myocardial infarction, sustained kidney injury, and myocardial revascularization) at 1 year were assessed. In the development set, optimal thresholds for contrast-induced AKI occurred at 6 hours for both urine NGAL (>=20 ng/mL; 97% negative predictive value and 27% positive predictive value) and sNGAL (>=179 ng/mL; 93% negative predictive value and 20% positive predictive value). Furthermore, sNGAL >=179 ng/mL at 6 hours was an independent predictor of 1-year MAE. 1-year MAE occurred in 27/198 patients (13.5%) with sNGAL <179 ng/mL and sCr <0.3 mg/dL, in 57/193 (29.5%) patients with only sNGAL >=179 ng/mL, and in 37/67 (55%) patients with sCr >=0.3 mg/dL. In additional 253 patients (validation set), no patient with urine NGAL <20 ng/mL or sNGAL <179 ng/mL at 6 hours developed contrast-induced AKI. Furthermore, 6/68 (9%) patients with sNGAL <179 ng/mL and sCr increase <0.3 mg/dL had 1-year MAE versus 17/57 (30%) patients with sNGAL >=179 ng/mL and sCr increase <0.3 mg/dL and 8/16 (50%) patients with sCr increase >=0.3 mg/dL. Conclusions--Urine NGAL <20 ng/mL and sNGAL <179 ng/mL at 6 hours are reliable markers for ruling out contrastinduced AKI. sNGAL >=179 ng/mL at 6 hours predicts 1-year MAE.