Normal values of B type natriuretic peptide in infants, children, and adolescents.

OBJECTIVE

To determine normal values of plasma B type natriuretic peptide from infancy to adolescence using a commercially available rapid assay.

SETTING

Tertiary referral centre.

DESIGN

The study was cross sectional. Plasma BNP concentration was measured in 195 healthy infants, children, and adolescents from birth to 17.6 years using the triage BNP assay (a fluorescence immunoassay).

RESULTS

During the first week of life, the mean (SD) plasma concentration of BNP in newborn infants decreased significantly from 231.6 (197.5) to 48.4 (49.1) pg/ml (p = 0.001). In all subjects older than two weeks plasma BNP concentration was less than 32.7 pg/ml. There was no significant difference in mean plasma BNP measured in boys and girls younger than 10 years (8.3 (6.9) v 8.5 (7.5) pg/ml). In contrast, plasma concentration of BNP in girls aged 10 years or older was significantly higher than in boys of the same age group (12.1 (9.6) v 5.1 (3.5) pg/ml, p < 0.001). Plasma BNP concentrations were higher in pubertal than in prepubertal girls (14.4 (9.7) v 7.1 (6.6) pg/ml, p < 0.001) and were correlated with the Tanner stage (r = 0.41, p = 0.001).

CONCLUSIONS

Plasma BNP concentrations in newborn infants are relatively high, vary greatly, and decrease rapidly during the first week of life. In children older than 2 weeks, the mean plasma concentration of BNP is lower than in adults. There is a sex related difference in the second decade of life, with higher BNP concentrations in girls. BNP concentrations in girls are related to pubertal stage.