A Simple Technique to Determine Thrombopoiesis Level Using Immature Platelet Fraction (IPF)

Abstract number: P0947

Abe¹ Y, Nishioka¹ J, Wada¹ H, Nobori¹ T, Kobayashi¹ T, Shiku¹ H, Oguni² S

¹¹Mie University School of Medicine, Tsu, Japan ¹¹Mie University School of Medicine, Tsu, Japan ²²Sysmex Corporation, Kobe, Japan

It was suggested that reticulated platelets (RP) might contain increased amounts of cytoplasmic RNA, reflecting the thrombopoiesis in bone marrow. The flow cytometric analysis has been used for RP assay, however it was difficult applying to routinely testing due to complicated operations. We developed a new automated RP testing method named as Immature Platelet Fraction (IPF) using XE-2100 automated hematology analyzer equipped with modified software and a polymethine dye. The aim of the study is to evaluate the IPF as indicator to discriminate level of thrombopoiesis. We have analyzed IPF in 129 healthy volunteers and 127 consecutive, unselected patients; idiopathic thrombocytopenic purpura (ITP, n= 51), aplastic anemia (AA, n= 24), post-chemotherapy (n= 23), hypercoagulable state (n= 19), stemcell transplant (n= 6), other diseases (n= 4). These patients were categorized to three groups which are different level of thrombopoietic phase as ‘suppressed’, ‘increased’ and ‘normal’ group. IPF were determined by the XE-2100 (Sysmex) with special designed software. Mean IPF value in healthy volunteer was 3.3 ± 1.7 (%). IPF in ‘increased’ group was significantly higher than ‘suppressed’ and ‘normal’ group). In ‘increase’ group, IPF was significantly elevated in ITP (especially active phase) and the peak value of IPF prior platelet recovery. The best cutoff point of IPF was chosen to discriminate ‘increased’ group from ‘suppressed + normal’ group was 6.15 (%). The sensitivity and specificity of this cutoff value are 80.0% and 90.1% for distinguish ‘suppressed + normal’ group, 80.0% and 83.7% for distinguish ‘suppressed’ group. The positive predictive value was 89.4%, and negative predictive value was 70.7% to detect the ‘increased’ group from ‘suppressed’ group. Our results suggest that the IPF reflects the thrombocytopenic disorders due to the level of thrombopoiesis. Our simple technique of IPF measurement is useful for the differential diagnosis and analysis of platelet kinetics.