The immature platelet fraction: creating neonatal reference intervals and using these to categorize neonatal thrombocytopenias.

Objective: The immature platelet fraction (IPF) is a laboratory measurement analogous to the reticulocyte count, but reflecting the thrombopoietic state. Similar to a reticulocyte count, it can be expressed as a percent (IPF%=percent of platelets that are immature) or as an absolute number per μl blood; the immature platelet count (IPC=IPF% × platelets per μl of blood).

Study Design: Using a retrospective analysis of de-identified data from non-thrombocytopenic neonates, we created reference intervals for IPF% and IPC.