Abstract 4472


Because there is no single clinical or laboratory finding for the diagnosis of essential thrombocythemia (ET), a differential diagnosis of other myeloproliferative neoplasms or reactive thrombocytosis (RT) is always necessary. Developments in automated blood cell analysers can now measure various platelet indices and were used in this study to differentiate between ET and RT in patients with a platelet count of 600×103/μL or more.


The subjects studied were 31 patients with ET and 224 patients with RT. The platelet counts, mean platelet volume (MPV), plateletcrit (PCT), platelet distribution width (PDW), mean platelet mass (MPM), mean platelet component concentration (MPC) and large platelets (LPLT) were measured by ADVIA 120 (Bayer Diagnostics, USA) and the sensitivity and specificity of the two groups were determined.


In essential thrombocythemia, all parameters except MPC were higher than those of reactive thrombocytosis and were statistically significant. The sensitivity and specificity were 74.2% and 84.4% when the platelet count was more than 820×103/μL. The sensitivity and specificity were 80.6% and 80.0% when the plateletcrit was more than 0.63%. The sensitivity and specificity were 64.5% and 99.1%, respectively, when LPLT was more than 23×103/μL.


The platelet counts and platelet indices are important for the differential diagnosis of thrombocytosis. The comparison of the plateletcrit and LPLT is particularly useful when the platelet count is markedly increased.


No relevant conflicts of interest to declare.

Author notes


Asterisk with author names denotes non-ASH members.