PC1118: Urine Biomarker Trends Among Very Low Birthweight Infants in the First Month of Life

Background: Neonatal AKI occurs in approximately 30% of all NICU admissions and is independently associated with mortality in VLBW infants, but is difficult to diagnose due to the physiologic limitations of traditional methods (serum sampling for creatinine and monitoring urine output) in neonates. We performed a prospective, descriptive pilot study to quantify the baseline incidence of AKI among VLBW infants in our NICU, demonstrate feasibility of urine sampling for AKI biomarker analysis, and describe normative values for urine biomarkers KIM-1, NGAL, IL-18, and TIMP2*IGFBP7 in the first 28 days of life among VLBW infants.

Methods: Infants admitted to the NICU over a six-month period born at less than 32 weeks gestation and weighing less than 1500g at birth were included. Baseline AKI incidence was defined by Neonatal Kidney Disease: Improving Global Outcomes (KDIGO) consensus criteria. Ten VLBW infants were recruited consecutively for prospective urine sampling; urine samples were obtained at 24, 48, 72 hours and 7 days, 14 days, and 28 days of life.

Results: Twenty-eight VLBW infants were born during the study period and were eligible for inclusion. Four infants (14.2%) experienced AKI KDIGO stage 1 or greater. Noninvasive urine sampling to monitor neonatal kidney function was feasible and acceptable to staff and caregivers based on study consent rates, completion rates and staff survey. Normative value curves for KIM-1, NGAL, IL-18, and TIMP2*IGFBP7 were generated for VLBW infants in the first 28 days of life and were correlated with serum creatinine sampling.

Conclusion: Our single-center study found a lower rate of neonatal AKI than previously described, likely owing to a low frequency of SCr sampling. Urine sampling for biomarkers of renal function in VLBW neonates is noninvasive, feasible, and may offer a more sensitive measure of early neonatal renal function in VLBW infants.