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

Background: The conventional therapeutic approach in polycythemic newborn i nfants is to apply partial exchange transfusion (PET) when hematocrit value exceeds 70% or when the infant develops symptoms with the exception of ple thora. Methods: In order to investigate the possibility of using platelet count as a simple criterion implying the PET requirement, we retrospectively review ed polycythemic newborn infants with respect to the relationship between th rombocytopenia and severity of symptoms, and the association of platelet co unt and the PET performance. Thrombocytopenia has been defined as a platele t 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 tox emia and intrauterine growth retardation, which are the three common causat ive factors leading to polycythemia, were not significantly different in th e two groups. No correlation existed between platelet counts and hematocrit values within each group, but there was a very significant difference betw een the two groups in terms of severity of clinical findings (P < 0001); no difference in terms of moderate findings and moderately significant differ ence with respect to mild symptoms and asymptomatic situation (P < 0.05). P artial exchange transfusion was performed in all patients in group 1, while only 12 infants in group 2 (32%) received transfusion and the difference w as statistically significant (P < 0.05). A significant rise in platelet cou nts has been achieved only in group 1, while hematocrit values decreased si gnificantly in both groups following PET. Conclusions: This study emphasizes the relationship between thrombocytopeni a and the severity of clinical findings and PET performance rate in polycyt haemic newborn infants, implying that thrombocytopenia is a possible marker of hyperviscosity, the results of which warrant further investigation.