Platelet-derived microparticles and platelet count in preterm newborns.

OBJECTIVE: Does formation of platelet-derived microparticles correspond to platelet activation? METHODS: The study was performed in 51 preterm newborns, 25 girls and 26 boys. The control group consisted of 55 term newborns, 25 girls and 30 boys. Blood samples were collected from the umbilical artery. The percentage of platelet-derived microparticles and platelet count were determined using flow cytometric analysis based on the CD61-positive antigen. RESULTS: The percentage of platelet-derived microparticles was higher in preterm newborns (5.46) in comparison to term newborns (4.22, p < 0.01). We found 4.61% of platelet-derived microparticles in preterm female newborns and 6.28% in preterm boys (p < 0.0070). The platelet count was 256 x 10(3) microl in girls and 238 x 10(3) microl in boys. Female healthy term newborns presented higher values of platelet-derived microparticles (4.4%) than male newborns (4.07%, p = 0.4725, table 1). The platelet count in girls was found to be 308 x 10(3) microl and in boys 270 x 10(3) microl. CONCLUSIONS: Higher percentage of platelet-derived microparticles in preterm newborns may provide a compensatory mechanism for the hemostatic system.

Does prematurity affect thrombocytopoiesis?

Data concerning thrombocytopoiesis in newborns are poorly recognized. Platelets have a crucial role in hemostatic physiology, which is deficient in newborns, especially in preterm newborns. A total of 51 preterm newborns (PTN), 25 girls and 26 boys, were recruited for the study. The control group consisted of 25 female and 30 male healthy term newborns (HTN). Plasma thrombopoietin (TPO) was measured using Quantikine human TPO system. Reticulated platelets (PLRET) was estimated by means of Retic-Count Kit. Platelet count (PLT) was determined using Advia(TU) 120 Hematology System. TPO was evidently higher in PTN (110.9 pg/ml) than in HTN (71.5 pg/ml), (p < 0.001). The percentage of reticulated platelets (PLRET) was also twice as high in PTN (3.49%) in comparison to HTN (1.7%), (p < 0.001). The PLT count was lower in PTN (246.7 x 10(3) microL) than in HTN (287.2 x 10(3) microL), (p < 0.01). Increased TPO levels and the percentage of PLRET indicate that thrombocytopoiesis is more active in prematurity. Our finding may be useful in therapeutic strategies.