Classification of thrombocytosis based on platelet function tests: correlation with hemorrhagic and thrombotic complications.

Abstract

Abstract Symptomatic and asymptomatic thrombocytosis occur in several myeloproliferative diseases. The purpose of this study was to determine whether platelet function tests could identify the subgroup of patients with thrombocytosis and a high risk of thrombosis and hemorrhage. Seventeen patients were studied. Group I consisted of 5 patients with reactive thrombocytosis; group II contained 7 patients with asymptomatic thrombocytosis and either polycythemia vera, myelofibrosis, or chronic myelogenous leukemia (CGL); and group III consisted of 5 patients with thrombocytosis, myeloproliferative disease, and recurrent thrombosis or hemorrhage. Coagulation tests included the bleeding time, platelet adhesiveness, and measurement of platelet aggregation and PF-3 activity in response to ADP (adenosinediphosphate), epinephrine, and collagen. The results were within normal limits in all patients in group I. Only minor platelet abnormalities were noted in 6 patients in group II. In contrast, all 5 patients in group III had an absence of epinephrine-induced platelet aggregation and PF-3 activity. Abnormalities of the bleeding time, platelet adhesiveness, and collagen-induced platelet aggregation were also noted in group III. Treatment of group III patients with 6-MP, 32 P, or busulfan resulted in reduction of platelet count to normal and improvement in the thrombotic and hemorrhagic manifestations. It is concluded that the combination of thrombocytosis and marked abnormality of platelet function is associated with a high risk of thrombotic and hemorrhagic complications.