The immature platelet fraction (IPF) in neonates

Young (immature) platelets containing residual RNA, so-called reticulated thrombocytes, appear in the peripheral blood after the release from bone marrow. It has been shown that the count of the reticulated platelet correlates with the megakaryocyte mass. As of late, the immature platelet fraction (IPF) may be reliably quantified with the fully automated blood analyzer Sysmex XE-2100. IPF may be expressed as percentage (IPF %) of the platelet count or as absolute number (IPF#)*. Since thrombocytopenia occurs in up to 30 % of all neonates admitted to intensive care, we evaluated the usefulness of IPF to estimate the platelet production rate in more than 1000 neonates. Our main findings are 1) the reference range for IPF in neonates (IPF % = 4.1 ± 1.8 %; IPF # = 9.5 ±3.8 x 10/ L) is higher compared to published results for adults and children, 2) a rise in IPF % anticipates increasing platelet counts, 3) IPF % inversely correlates with the platelet count, indicating a similar mechanism of neonatal thrombocytopenia that is mainly caused by platelet consumption, 4) IPF # is decreased in neonates with severe thrombocytopenia by approximately 50 % (IPF # 4.7 x 10/ L), indicating that a decreased megakaryopoietic activity contributes to the development of severe thrombocytopenia. We conclude that IPF can support decision-making when to monitor platelet counts in the setting of neonatal intensive care. Furthermore, the absolute IPF # should be taken into account for exact estimation of the platelet production rate. Malte Cremer, M. D. Department of Neonatology Charité – Universitätsmedizin Berlin. Charitéplatz 1, d-10117 Berlin, Germany The immature platelet fraction (IPF) in neonates