* Corresponding author: Rozita Hoseini, Iran University of Medical Sciences, Tehran, Iran. Tel: +982186709; Email: rozitahoseini@yahoo.com Please cite this paper as: Khosravi N, Seirafianpour F, Mashaiekhi M, Safari S, Khalesi N, Otukesh H, Hoseini R. Importance of Urinary NGAL Relative to Serum Creatinine Level for Predicting Acute Neonatal Kidney Injury. Iranian Journal of Neonatology. 2020 Dec: 11(4). DOI: 10.22038/ijn.2020.43344.1719 Original Article Open Access Importance of Urinary NGAL Relative to Serum Creatinine Level for Predicting Acute Neonatal Kidney Injury Nastaran Khosravi 1 , Farnoosh Seirafianpour 2 , Mehdi Mashaiekhi 1 , Sepideh Safari 3 , Nasrin Khalesi 1 , Hasan Otukesh 1 , Rozita Hoseini 1* 1. Iran University of Medical Sciences, Tehran, Iran 2. Student Research Committee, school of medicine, Iran University of Medical Sciences, Tehran, Iran 3. Razi Drug Research Center, Iran University of Medical Sciences, Tehran, Iran 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. 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. 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). 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. Keywords: Acute kidney injury, Creatinine, Neonates, NGAL, Predicting AKI Introduction Acute kidney injury (AKI) is a leading cause of neonatal mortality and morbidity (1-4). The true etiology of acute neonatal kidney injury is multifactorial with a combination of many causes, such as ischemia, reperfusion damage, disturbance of homeostasis of the renal vasomotor, hypoxic and oxidative stress, and cytokine-driven impact. In other words, the identified mechanisms affecting kidney functional include altered renal perfusion, vasomotor nephropathy, severe sepsis, and drug-induced nephrotoxicity. The diagnosis of this injury is routinely based on the calculation of glomerular filtration rate based on serum creatinine; however, this method appears to be unreliable due to the potential effects of underlying demographic and metabolic parameters on serum and urine creatinine levels. Therefore, recent studies have focused on new diagnostic specific markers with high sensitivity and accuracy for the early prediction of acute