Changes in thrombopoiesis and platelet reactivity in extremely low birth weight infants undergoing erythropoietin therapy for treatment of anaemia of prematurity. 
Erythropoietin (Epo) is frequently administered to premature infants to stimulate erythropoiesis.  There is evidence from studies in animals and healthy adults that Epo also interacts with thrombopoiesis and platelet function.  This study investigates the effect of Epo therapy on platelet reactivity, peripheral platelet counts and thiazole orange-positive (TO+) platelets in extremely low birth weight (ELBW) infants.  In a randomised-controlled trial, ELBW infants with a birth weight < or =800 g and a gestational age < or =32 weeks were either randomised to a group receiving Epo during the first weeks of life or to a control group.  Our results show that thrombin receptor-activating peptide (TRAP-6) -induced expression of P-selectin increased significantly during the first two weeks of Epo treatment.  With the exception of week five, the number of TO+ platelets was significantly higher during the first eight weeks in Epo-treated infants compared to controls.  The increase of TO+ platelets was not paralleled by an increase in total platelet count.  We can conclude that Epo therapy has a short-lasting effect on platelet reactivity toTRAP-6 in ELBW infants during the first two weeks of life.  Furthermore, Epo therapy is associated with an increase in the number of TO+ platelets compared to controls.