Neutrophil gelatinase-associated lipocalin as an early marker of acute kidney injury in patients with traumatic brain injury.

BACKGROUND: Recent studies have shown that urinary neutrophil gelatinase-associated lipocalin (NGAL) is rapidly up-regulated early after murine renal injury, and in patients after cardiac surgery or patients critically ill with multiple trauma. In this study, we evaluated urinary NGAL levels as a potential biomarker of early acute kidney injury (AKI) in patients with severe traumatic brain injury (TBI).

METHODS: All patients with severe TBI admitted to our neurosurgical intensive care unit from March to September 2011 were enrolled prospectively. Urinary NGAL was measured using a chemiluminescent microparticle immunoassay upon admission and at 24 and 48 hours after TBI. The presence of AKI was defined by the Acute Kidney Injury Network (AKIN) criteria.

RESULTS: Using AKIN criteria, a total of 13 patients were identified with AKI, an incidence of 24%. Those who subsequently developed AKI had a striking rise in urinary NGAL early after TBI and a sustained increase over the entire duration of the study. The urinary NGAL level of the AKI group was significantly higher than the group without AKI at all time points. Using a cutoff value of 53.9 ng/mL, the area under the receiver-operating characteristic curve for urinary NGAL at 48 hours was 0.876 with a sensitivity of 0.69 and specificity of 0.95.

CONCLUSIONS: Increased urinary NGAL is associated with an increased occurrence of AKI in patients with severe TBI. It is possible that urinary NGAL could provide a screening tool for AKI immediately after severe TBI, and this may in turn allow early intervention to ameliorate the adverse effects of AKI.