Stability of measurement of the immature platelet fraction
Purpura, Thrombocytopenic, Idiopathic
Immune Thrombocytopenia (ITP) is a heterogeneous clinical entity for which no simple diagnostic test exists. The Immature Platelet Fraction (IPF), a marker of Reticulated Platelets (RP), is a good indicator of thrombopoiesis and can identify accelerated destruction of platelets by demonstrating compensatory increased platelet production. Measuring IPF is not routinely available in clinical practice; it has proven useful in studies of thrombocytopenia and the novel thrombopoietic agents. A multicenter clinical trial would be needed to explore IPF in management of patients with ITP; such a trial would require central testing. Therefore, we sought to assess the reliability of measured platelet counts and IPF in whole-blood filled EDTA tubes when the same tube is run freshly and again 24 hr after venipuncture. Based on analysis of our 103 samples, it is clear that EDTA tubes are stable at room temperature for 24 hr. Therefore, the results can be used to estimate thrombopoiesis when measured within 24 hr after phlebotomy.