Urinary biomarkers of acute kidney injury in neonates < 25 weeks' gestation: a pilot study.

BACKGROUND: Acute kidney injury (AKI) occurs in 30% of premature neonates and is associated with adverse outcomes that may be mitigated with early detection. Diagnosis of AKI relies on serum creatinine (SCr) which has several limitations, including lack of sensitivity and specificity. There are limited data on the utility of alternative urine biomarkers to predict AKI in neonates born at < 25 weeks' gestation. METHODS: Urine was collected from neonates born at < 25 weeks' gestation during the first postnatal week. Two urine AKI biomarkers, neutrophil gelatinase-associated lipocalin (NGAL) and epidermal growth factor (EGF) were measured. Study participants were prospectively followed to determine development of AKI, defined by the neonatal modified Kidney Disease-Improving Global Outcomes (KDIGO) criteria, during the first postnatal week. The association of NGAL and EGF with AKI was analyzed using mixed-effect linear regression models adjusting for gestational age at birth. RESULTS: A total of 26 neonates were enrolled in this study. After adjusting for gestational age at birth, the mean difference in log-transformed biomarkers at three time points for urine NGAL and EGF was not statistically different between cases and controls. Although the urinary biomarkers studied were not associated with diagnosis of AKI, AKI was associated with lower birth weight (p = 0.02). CONCLUSIONS: This study provides preliminary information about urine NGAL and EGF in neonates < 25 weeks' gestation, a growing patient population at high risk for kidney injury. The relationship between urinary biomarkers and outcomes in this population warrants further investigation.