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


METHODS
On 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).


RESULTS
In 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.


CONCLUSIONS
The 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.
Bednarek
Francis J
FJ
Neonatology, Department of Pediatrics, University of Massachusetts Medical School and UMass Memorial Health Care, Worcester, MA 01655, USA.
Bean
Stephen
S
Barnard
Marc R
MR
Frelinger
A L
AL
Michelson
Alan D
AD
D000328:Adult; D000367:Age Factors; D001792:Blood Platelets / Q000378:metabolism*; D005165:Factor V / Q000378:metabolism*; D015943:Factor Va / Q000378:metabolism*; D006801:Humans; D052577:Infant, Extremely Low Birth Weight; D007231:Infant, Newborn; D019007:P-Selectin / Q000378:metabolism*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism*
D019007:P-Selectin; D019038:Platelet Glycoprotein GPIb-IX Complex; D015943:Factor Va; D005165:Factor V