Thrombocytopenia:: An important indicator for the application of partial exchange transfusion in polycythemic newborn infants?

Background: The conventional therapeutic approach in polycythemic newborn infants is to apply partial exchange transfusion (PET) when hematocrit value exceeds 70% or when the infant develops symptoms with the exception of plethora. Methods: In order to investigate the possibility of using platelet count as a simple criterion implying the PET requirement, we retrospectively reviewed polycythemic newborn infants with respect to the relationship between thrombocytopenia and severity of symptoms, and the association of platelet count and the PET performance. Thrombocytopenia has been defined as a platelet count < 150 000/mu L. Results: We studied 18 polycythemic infants with thrombocytopenia (group 1, 35%) and 34 without it (group 2, 65%). Perinatal asphyxia, gestational toxemia and intrauterine growth retardation, which are the three common causative factors leading to polycythemia, were not significantly different in the two groups. No correlation existed between platelet counts and hematocrit values within each group, but there was a very significant difference between the two groups in terms of severity of clinical findings (P < 0001); no difference in terms of moderate findings and moderately significant difference with respect to mild symptoms and asymptomatic situation (P < 0.05). Partial exchange transfusion was performed in all patients in group 1, while only 12 infants in group 2 (32%) received transfusion and the difference was statistically significant (P < 0.05). A significant rise in platelet counts has been achieved only in group 1, while hematocrit values decreased significantly in both groups following PET. Conclusions: This study emphasizes the relationship between thrombocytopenia and the severity of clinical findings and PET performance rate in polycythaemic newborn infants, implying that thrombocytopenia is a possible marker of hyperviscosity, the results of which warrant further investigation.