Summary

Background: Cardiac patients express elevated levels of B-type natriuretic peptide and the amino terminal segment of its prohormone (NT-proBNP). However, there are non-cardiac causes of NT-proBNP level elevation.

Objectives: To determine the upper limit of NT-proBNP for pediatric patients with acute non-cardiac disease.

Methods: We compared NT-proBNP concentrations in healthy children and children with acute non-cardiac, mostly febrile, and acute cardiac disease. We used the Student t-test and Mann-Whitney test for group comparisons, and Pearson's and Spearman's correlation coefficients to test relationships between variables. 

Results: In 138 patients with acute non-cardiac diseases (mean age 3.7 years, 53% male), median NT-proBNP concentration was 162 pg/ml, upper limit (95% percentile) 1049 pg/ml. The level did not vary significantly by disease category; was negatively correlated with weight, weight percentile, age and hemoglobin level; and positively correlated with creatinine level. Multivariant analysis showed weight to be the only factor influencing NT-proBNP level. Levels were higher in children with acute non-cardiac diseases versus healthy children (median 88 pg/ml, P < 0.001, n= 59), and lower than levels in patients with acute cardiac disease (median 29,986 pg/ml, P < 0.001, n=29). Receiver operating characteristic analysis showed good NT-proBNP performance for differentiation between children with acute cardiac versus non-cardiac disease (area under the curve 0.958), at a cutoff of 415 pg/ml.

Conclusions: NT-proBNP levels are higher in children with acute non-cardiac diseases than in healthy children, but lower than in children with acute cardiac disease. NT-proBNP negatively correlated with weight and weight percentile.