Plasma concentrations of aminoterminal pro atrial natriuretic peptide and aminoterminal pro brain natriuretic peptide in healthy neonates:: Marked and rapid increase after birth

Objective. The purpose of the study was to examine the possible age dependency of plasma N-terminal pro atrial natriuretic peptide (N-ANP) and N-terminal pro brain natriuretic peptide (N-BNP) levels in healthy term neonates to establish normal ranges for the neonatal period. Methods. N-ANP and N-BNP plasma concentrations were measured in peripheral venous (n = 116) and umbilical cord blood ( n = 37) in 153 healthy term neonates (mean: 5.1; range: 0 - 30 days) using an enzyme immunoassay. The neonates were classified into 8 groups according to their age ( day of delivery and 1, 2, 3, 4, 5 - 7, 8 - 14, and 14 - 30 days of age). Results. The plasma N-ANP and N-BNP concentration were the highest at the first day of age ( 96 700; 6912 - 436 000 and 641; 254-1272 fmol/mL) and were found significantly higher compared with the day of delivery ( 5680; 1005 - 16 900 and 221; 58 - 478 fmol/mL; P < 0,0001). After this marked increase, N-ANP and N-BNP levels decreased steadily and became stable at the fifth ( 5232; 2691 - 7353 fmol/mL) and third ( 246; 110 - 430 fmol/mL) day of life, respectively. Conclusions. The N-ANP and N-BNP plasma concentrations in healthy neonates showed a marked increase during the first days of age, suggesting that ANP and BNP have physiologic roles in the perinatal circulatory change from fetus to neonate.