The trend of urinary NT-proBNP in extremely low birth weight infants during the neonatal period

Background: NT-proBNP is a biomarker of interest in many cardiopulmonary diseases in extremely low birth weight (ELBW) Infants. However, there is a gap in knowledge about the trend of ELBW infant’s urinary NT-proBNP during the neonatal period. Aim: To determine the trend of urinary NT-proBNP during the first four weeks of life of an ELBW infant Study Design: We analyzed prospectively enrolled, 87 ELBW infants. Urinary NT-proBNP to creatinine ratios were measured on days 1-7, day 14, and day 28 of life. In addition, we plotted each study point's means to determine the trend of urinary NT-proBNP over the entire neonatal period. Data were analyzed using the Friedman ANOVA for comparative analysis of study points. Results: Urinary NT-proBNP/creatinine ratios were significantly elevated on days 1-7 (mean 2452, + 1518) than day 14 (mean 747, +176), and day 28 (mean149, +54), p=0.001. Overall, urinary NT-proBNP levels were highest during the days 1-3 (mean 3232+1255) and lowest on day 28 (mean149, +54). Conclusions: Urinary NT-proBNP levels are higher during the first week in ELBW infants with a downward trend during the neonatal period, with the lowest values at four weeks postnatal age. More studies are required to determine the clinical utility of this trend during and beyond the neonatal period.