Reference values for N-terminal Pro-brain natriuretic peptide in premature infants during their first weeks of life

The aim of our study was to observe the temporal distribution of serum N-terminal pro-brain natriuretic peptide (NT-proBNP) in premature infants of ≤ 31 weeks of gestational age (GA) during the first weeks of life. NT-proBNP values of 118 preterm infants born ≤ 31 weeks GA were determined during the first week of life, after 4 ± 1 weeks of life, and at a corrected GA of 36 ± 2 weeks. Infants were divided into two groups: those without relevant complications and those with complications related to prematurity. NT-proBNP values of infants without complications define our exploratory reference values. The Median NT-proBNP level of these infants was 1896 ng/l (n = 27, interquartile range (IQR): 1277-5200) during the first week of life, 463 ng/l (n = 26, IQR: 364-704) at 4 ± 1 weeks of life, and 824 ng/l (n = 33, IQR: 714-1233) at a corrected GA of 36 ± 2 weeks. Infants born < 28 + 0 weeks GA had significantly higher NT-proBNP values (n = 9, median: 5200, IQR: 1750-8972) than infants born ≥ 28 + 0-31 weeks GA (n = 18, median: 1528, IQR: 838-3052; p = 0.017). Growth restriction or PDA status could not account for the difference in NT-proBNP values between GA groups.Conclusions: The results of our observational and cross-sectional study describe exploratory reference values for NT-proBNP levels in preterm infants of ≤ 31 weeks GA according to postnatal age. NT-proBNP levels during the first week of life are high and widely distributed in preterm infants and decrease subsequently to reach a distinctly lower and stable plateau at around 1 month of life. Our results suggest an influence of GA on NT-proBNP values in the first week of life. What is Known: • Several complications related to prematurity, e.g., hemodynamically significant PDA, pulmonary hypertension, bronchopulmonary dysplasia, and retinopathy of prematurity, have been associated with a temporary rise in NT-proBNP values in preterm infants during their first weeks of life. What is New: • This observational study provides reference values for NT-proBNP levels of very and extremely preterm infants during their first weeks of life. • In premature infants without complications, NT-proBNP values during their first week of life depend on gestational age at birth.