Evaluation of plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) as an early diagnostic marker of acute kidney injury (AKI) in critically ill trauma patients

BACKGROUND AND AIMS: Acute kidney injury (AKI) is a frequent complication of severe trauma associated with high mortality. The aim of this study was to evaluate the diagnostic ability of plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) as an early marker of AKI assessed by RIFLE criteria as reference in trauma patients in intensive care unit (ICU). MATERIAL AND METHODS: This was a prospective observational study. Four hundred and eighteen patients admitted in the trauma ICU with age ≥18 years without known renal diseases were followed-up (serum creatinine, urine output, and estimated glomerular filtration rate) for 5 consecutive days. As per RIFLE criteria, 70 patients were broadly classified as AKI and rest of the patients (n = 348) as non-AKI. Plasma and urine samples of AKI (n = 70) and non-AKI (n = 70) patients were further assessed for 3 consecutive days following admission. RESULTS: Mean plasma NGAL (pNGAL) was significantly elevated in AKI patients as compared with non-AKI patients; on admission: 204.08 versus 93.74 ng/mL (P = 0.01); at 24 h: 216.73 versus 94.63 ng/mL (P = 0.01); and 48 h: 212.77 versus 86.32 ng/mL (P = 0.01). Mean urine NGAL (uNGAL) at 48 h was also significantly elevated: 15.45 ng/mL in AKI patients as compared with 13.48 ng/mL in non-AKI patients (P = 0.01). Plasma and urine NGAL levels were significantly associated with increased mortality. CONCLUSION: pNGAL had good predictive value on admission (area under the receiver operative characteristic [AUROC] 0.84), at 24 h (AUROC 0.88) and 48 h (AUROC 0.87), while uNGAL had moderate performance at 24 h (AUROC 0.61) and 48 h (AUROC 0.71). pNGAL can be used as an early and potent diagnostic and predictive marker of AKI and mortality in critically ill trauma patients.