Comparison between BNP and NT-proBNP in pediatric populations

Background: B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are essential biomarkers for the evaluation of cardiac pathologies. However, pediatric reference intervals for BNP and NT-proBNP are not well defined and concordance between them in the evaluation of pediatric patients has been poorly described.

Methods: Paired BNP and NT-proBNP testing was performed on 311 specimens representing 175 pediatric patients. Pediatric BNP and NT-proBNP reference intervals derived from the literature were used to evaluate concordance of results based on age group and cardiac pathology.

Results: Deming regression analysis of BNP and NT-proBNP results revealed a slope of 13.63 (95% CI, 10.35-16.92) and y-intercept of -977.8 (-2063-107.2) with a positive Spearman correlation (r = 0.91). By age group, concordance kappa between BNP and NT-proBNP was 1.0 for 0-10 days, 0.23 (0-0.62) for 11-30 days, 0.82 (0.67-0.97) for 31 days-1 year, 0.81 (0.57-1.0) for 1-2 years and 0.73 (0.64-0.86) for 2-18 years. The ratio of NT-proBNP to BNP was lowest in heart transplant patients (ratio, 6.5 [95% CI, 5.1-8.1]) relative to those with heart disease (10.5 [8.8-13.7]) and pulmonary hypertension (14.2 [11.3-16.0]) but no differences in concordance were observed. For serial specimens, 21% displayed inverse, discordant changes in BNP and NT-proBNP results. Review of discordant serial results revealed that kinetics of changes was comparable and unlikely to be clinically significant.

Conclusions: There is positive correlation and moderate concordance between BNP and NT-proBNP in the pediatric population studied.