Perioperative urinary NT-ProBNP values and their usefulness as diagnostic and prognostic markers in children with congenital heart disease.

INTRODUCTION: NT-proBNP and especially the changes in values are important markers in patients with congenital heart disease (CHD). NT-proBNP values determined from a urine sample correlate well with the plasma values of NT-proBNP. This study investigated the perioperative development of plasma and urinary values, examining their diagnostic and prognostic value. METHODS: 83 children undergoing cardiac surgery for a myriad of CHDs were included. Urine and plasma samples were collected at different points in time. Urinary values were corrected for urine creatinine concentration and transformed into Lg10-values. RESULTS: The correlation between urine and plasma is weaker postoperatively (r = 0.70-0.80) in comparison to preoperatively (r = 0.87). Neonates had higher urinary values than older children. A ROC-analysis for the differentiation between complex and simple CHD showed an area under the curve of 0.854 for zlog-NT-proBNP plasma values and 0.826 for creatinine corrected urine values. A decline of NT-proBNP plasma values from the day before surgery to the time after intubation correlated with the duration of postoperative non-invasive ventilation (r = 0.9, sig. < 0.001). CONCLUSION: Urinary NT-proBNP shows potential in discriminating between complex and simple CHD. This study is the first to show a prognostic role of NT-proBNP in establishing spontaneous respiration postoperatively in children with CHD.

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.