Plasma atrial natriuretic polypeptide concentration in healthy children from birth to adolescence.

We measured plasma atrial natriuretic polypeptide concentrations in the umbilical artery and vein, and peripheral veins of healthy children from birth to adolescence to establish the normal range. The plasma atrial natriuretic polypeptide concentration in the umbilical artery (mean +/- SD, 51.0 +/- 21.4 fmol/ml) was significantly higher than that in the umbilical vein (18.1 +/- 13.5 fmol/ml) in neonates after vaginal delivery. Also neonates aged 5 days or less had a significantly high concentration in the peripheral vein (60.7 +/- 29.4 fmol/ml). There was no significant difference in atrial natriuretic polypeptide concentrations in the peripheral veins between older children and adults. The concentrations in children aged more than 5 days and adults aged 20-34 years were 14.4 +/- 7.4 fmol/ml and 10.0 +/- 4.8 fmol/ml, respectively. However, the atrial natriuretic polypeptide concentration in the umbilical artery was not increased in three neonates delivered by caesarean section although they had a high concentration in the peripheral vein 24 hours after birth.