Importance of Urinary NGAL Relative to Serum Creatinine Level for Predicting Acute Neonatal Kidney Injury

Abstract

Background: The diagnosis of acute kidney injury (AKI) is focused on the measurement of glomerular filtration rate based on serum creatinine; nevertheless, due to the effects of the underlying confounding parameters, this procedure tends to have some problems. Recent findings identified neutrophil gelatinase-associated lipocalin (NGAL) to be a critical marker for predicting AKI in humans. The aim of the present study was to evaluate changes in urinary NGAL levels in neonates with AKI and those without AKI.<br />Methods: This cross-sectional analytical study was conducted on a total of 75 neonates hospitalized for AKI and 81 neonates hospitalized for reasons not related to kidney disease. The serum concentrations of NGAL creatinine and urine were measured in both groups.<br />Results: The mean NGAL levels were 825.81±175.08 and 292.20±322.03 ng/ml in the case and control groups with a substantial difference, respectively. The NGAL had a sensitivity of 100%, specificity of 55.6%, positive predictive value of 67.6%, negative predictive value of 100%, and accuracy of 76.9% in predicting AKI. Assessing the region under the receiver operating characteristic curve (ROC curve) showed that measurement by NGAL effectively discriminated AKI from normal conditions (area under the ROC curve=0.899). The NGAL's best cut-off value for predicting AKI among neonates was estimated at 427 ng/ml, resulting in a sensitivity of 100% and specificity of 67.9%. Using Pearson's correlation coefficient test revealed a strong linear connection between the NGAL level and altered creatinine level (r=0.395; p <0.001).<br />Conclusion: The measurement of urinary NGAL in predicting AKI among neonates has high sensitivity and proper specificity, compared to that reported for the creatinine level.