Urinary neutrophil gelatinase-associated lipocalin identifies critically ill young children with acute kidney injury following intensive care admission

__Introduction__ Children admitted to a pediatric intensive care unit (ICU) are at high risk of developing acute kidney injury (AKI). Although serum creatinine (SCr) levels are used in clinical practice, they are insensitive for early diagnosis of AKI. Urinary neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (KIM-1) are novel AKI biomarkers whose performance in pediatric ICU patients is largely unknown. In this study, we aimed to characterize uNGAL and KIM-1 patterns in children following ICU admission and to assess their properties in relation to identifying children at risk for AKI development. __Methods__ From June 2010 until January 2014, we conducted a prospective observational cohort study of term-born children ages 1day to 1year on mechanical ventilation. Blood and urine samples were obtained every 6 to 12hours up to 72hours post-admission. Blood samples were assayed for SCr, and urine samples were assayed for uNGAL and KIM-1. The RIFLE (risk, injury, failure, loss, end-stage renal disease) classification as 150%, 200% or 300% of median SCr reference values was used to define AKI. __Results__ A total of 100 children were included (80 survived). Their median age at admission was 27.7days (interquartile range (IQR), 1.5 to 85.5). The median duration of mechanical ventilation was 5.8days (IQR, 3.1 to 11.4). Thirty-five patients had evidence of AKI within the first 48hours post-admission, of whom 24 (69%) already had AKI when they entered the ICU. uNGAL and KIM-1 concentrations in AKI peaked between 6 to 12hours and between 12 to 24hours post-admission, respectively. The maximal area under the receiver operating characteristic curve (AUC) for uNGAL was 0.815 (95% confidence interval (CI), 0.685 to 0.945, P <0.001) at 0 to 6hours post-admission. The discriminative ability of KIM-1 was moderate, with a largest AUC of 0.737 (95% CI, 0.628 to 0.847; P