Patent ductus arteriosus (PDA) is common in preterm infants and is associated with significant morbidities. B type natriuretic peptide (BNP) is synthesized in the ventricles secondary to volume overload and excreted as urinary N-terminal pro-brain natriuretic peptide (NT-proBNP).STUDY DESIGN:
We report an observational prospective study of 64 preterm infants with birth weight ≤1000 g. Echocardiographic parameters were obtained from clinical echocardiograms performed in the first week of life. Urinary NT-proBNP/creatinine ratios (pg mg-1) were measured on the same day of the echocardiograms.RESULTS:
Infants with medium to large PDA (n = 39) had significantly higher NT-proBNP/creatinine levels compared with infants with small PDA (n = 10) (median (IQ range): 2333 (792–6166) vs 714 (271–1632) pg mg-1, P = 0.01) and compared with infants with no PDA (n = 15) (2333 (792–6166) vs 390 (134–1085) pg mg-1, P = 0.0003). Urinary NT-proBNP/creatinine ratios were significantly lower post treatment if PDA closed (n = 17), P = 0.001 or if PDA became smaller after treatment (n = 9), P = 0.004. Urinary NT-proBNP/creatinine levels correlated with ductal diameter (P ≤ 0.0001), but not with LA/Ao ratio (P = 0.69) or blood flow velocity through the ductus (P = 0.06).CONCLUSION:
Our findings indicate that there is a positive correlation between ductal diameter and urinary NT-proBNP in preterm infants.