Supplementary Material for: Urinary Nephrin as a Biomarker of Glomerular Maturation and Injury Is Associated with Acute Kidney Injury and Mortality in Critically Ill Neonates

<b><i>Background:</i></b> Nephrin is a key component of the slit diaphragm of the glomerular podocyte, and increased urinary nephrin level may reflect glomerular injury. <b><i>Objectives:</i></b> To determine whether urinary nephrin is a useful biomarker of glomerular maturation and injury and whether it is associated with acute kidney injury (AKI) and neonatal intensive care unit (NICU) mortality in critically ill neonates. <b><i>Methods:</i></b> Urinary samples were serially collected in 234 neonates during NICU stay for measurements of nephrin, cystatin C (CysC), and albumin. AKI diagnosis was based on neonatal Kidney Disease: Improving Global Outcome (KDIGO) criteria. <b><i>Results:</i></b> Of the neonates, 26 developed AKI and 24 died during NICU stay. The independent contributors to the initial urinary nephrin level obtained on the first 24 h admitted to NICU were gestational age (<i>p</i> = 0.004) and initial urinary CysC level (<i>p</i> &lt; 0.001). Both initial (<i>p</i> = 0.037) and peak (<i>p</i> = 0.039) urinary nephrin were significantly associated with AKI, even after controlling for significant covariates, and had an area under the receiver-operating characteristic curve (AUC) of 0.71 and 0.70, respectively, for predicting AKI. At the optimal cutoff value of 0.375 μg/mg urinary creatinine, the initial urinary nephrin displayed sensitivity of 61.5% and specificity of 76.9% for predicting AKI. The AUCs for initial and peak urinary nephrin to predict NICU mortality were 0.81 and 0.83, respectively. <b><i>Conclusions:</i></b> Urinary nephrin, which may decrease with increasing glomerular maturity, is significantly associated with increased risk for AKI and NICU mortality even after adjustment for potential confounders. A higher level of urinary nephrin may be independently predictive of AKI and NICU mortality in critically ill neonates.