Urinary values of NT-proBNP in children with congenital heart disease - Is it feasible?

Plasma NT-proBNP (N-terminal prohormone of brain natriuretic peptide) is an established clinical biomarker for children with congenital heart disease. In adult studies the relation between plasma and urinary NT-proBNP has been investigated with a good correlation. Considering the age dependence of NT-proBNP in healthy children and the age dependence of kidney function, an investigation of the correlation between NT-proBNP plasma and urinary values in children of different ages is necessary. We analyzed plasma and urine samples of 33 children (mean age 7 months) with congenital heart disease before surgery. Plasma and urinary creatinine were also measured to evaluate the influence of kidney function. A Pearson correlation between Lg10-plasma and Lg10-urine values of NT-proBNP corrected for urine creatinie showed a correlation coefficient of r = 0,902 (P < 0,000) without discriminating for age. This study demonstrates that urinary NT-proBNP values correlate well with plasma NT-proBNP values in infants and toddlers and that single random urine sample corrected to urine-creatinine can be used as an alternative to plasma samples. The use of urinary biomarkers could help reduce the need of stressful blood sampling in infants and children.