Utility of Platelet Indices to Differentiate Reactive vs Clonal Thrombocytosis

Introduction- Thrombocytosis can be due to various causes. Modern hematology analyzers estimate various platelet indices including platelet count, MPV (mean platelet volume), PCT (plateletcrit) and PDW (platelet distribution width). Platelet indices have been used to differentiate various causes of thrombocytosis. This study was undertaken to assess the utility of platelet indices. Materials and Methods- Patients who presented to the Pathology department, for bone marrow studies, with persistent platelet count 4.5x109 /L were included in the study, along with 20 normal controls. Correlating the clinical features, peripheral blood and marrow studies, cases of thrombocytosis were classified as reactive (20) and clonal (40). These were compared with the normal (20) group. The various platelet indices, like platelet count, MPV, PCT and plateletcrit were estimated using automated hematology analysers. The data was analysed using unpaired t-test and chi square test. Results- There was no significant difference of platelet counts between the reactive and clonal groups. The values of PDW and plateletcrit were found to be significantly higher in the clonal group than the reactive group. Though the MPV values of all groups are within normal limits the mean values are significantly higher in the clonal group compared to reactive group. Conclusion- MPV, PDW and PCT values were found to be significantly higher in clonal group when compared to reactive groups. Platelet indices may help us to predict whether thrombocytosis is of reactive or clonal etiology, hence helping us to decide further ancillary tests.