Importance of the Immature Platelet Fraction in the Etiological Diagnosis of Thrombocytopenia

Abstract

Thrombocytopenia is defined as a platelet count of less than 150 G/L in the blood. It can be of central or peripheral origin. Newly-formed immature platelets are called reticulated platelets (RP) and are expressed as the immature platelet fraction or IPF. This automated hematological parameter enables us to distinguish between peripheral and central thrombocytopenia in a simple, quick, easily reproducible and non-invasive way. In the present study, our aim was to evaluate the clinical utility of the IPF and its ability to differentiate between central and peripheral thrombocytopenia. In this prospective study, we collected 50 cases of thrombocytopenia in our series. The IPF and all other CBC parameters were measured using the Sysmex XN-1500 analyser. Based on the clinical context and myelogram findings, the subjects in our study were separated into a central thrombocytopenia group and a peripheral thrombocytopenia group. We then assessed variations in IPF between the two groups. The mean IPF in the peripheral thrombocytopenia group was significantly higher than that in the central thrombocytopenia group (15.71 ± 12.02% vs. 5.51 ± 3.04%; p<0.001) and this difference persisted regardless of platelet count. We also established a sensitivity and specificity ROC curve, which showed that the IPF had excellent diagnostic value for differentiating between central and peripheral thrombocytopenia, with an area under the curve of 0.914. We also defined a discriminative cut-off value of 8.5% with a sensitivity of 77.8% and a specificity of 86.4% for defining the origin of thrombocytopenia. Thus, an IPF value above 8.5% points to peripheral thrombocytopenia with increased platelet regeneration. In conclusion, the results of our study have enabled us to formulate recommendations for improving the diagnostic strategy for thrombocytopenia using the immature platelet fraction or IPF.