The platelet hyporeactivity of extremely low birth weight neonates is age-dependent

IntroductionWe have previously demonstrated that, as compared to adults, the platelets of extremely low birth weight (ELBW) neonates are markedly hyporeactive on day 0 – 1 of life. The purpose of this study was to examine the age dependency of this hyporeactivity.Materials and MethodsOn days 0 – 1, 3 – 4, and 10 – 14, peripheral blood was collected from 14 stable ELBW neonates and compared to peripheral blood from normal adults run in parallel. Whole blood flow cytometry was used to examine the activation-dependent increase in platelet surface P-selectin (reflecting degranulation) and platelet surface binding of factor V/Va (reflecting platelet surface procoagulant activity) and decrease in platelet surface glycoprotein (GP) Ib (the von Willebrand factor receptor).ResultsIn the physiologic milieu of whole blood, ELBW neonatal platelets on days 0 – 1 and 3 – 4 were markedly less reactive than adult platelets. However, by day 10 – 14, the platelet function of ELBW neonates improved significantly, although not completely to adult levels.ConclusionsThe age-dependent platelet hyporeactivity of ELBW neonates demonstrated in this study may be a contributing factor to the similar age-dependent propensity of ELBW neonates to intraventricular hemorrhage.