Platelet and fibrinogen kinetics in the chronic myeloproliferative disorders

Simultaneous platelet and fibrinogen survival kinetic studies utilizing 75Seselenomethionine was performed on six patients with chronic myelogenous leukemia (CML), four with polycythemia vera (PV), one with idiopathic thrombocytosis (IT), and seven with myelofibrosis and myeloid metaplasia (MMM). The data revealed that platelet survivals, as well as fibrinogen survivals, were increased in CML as compared to patients with the other myeloproliferative disorders (MPD). Platelet survival was shortened in the patients with MPD as compared to the control patients. Thrombotic episodes were noted in three patients with MPD, while another had recurrent rectal bleeding. In all of these patients, platelet turnover was increased and was the only consistent determinant of hemostatic abnormality. Platelet adhesiveness and aggregation studies were inconsistently altered in any group and were not useful predictors of the risk of hemorrhagic or thrombotic diathesis. The data suggest that the platelets produced by patients with CML are functionally abnormal and underutilized when compared to control patients and to patients with other MPD. The thrombocytosis of CML results from decreased platelet utilization rather than from overproduction. Overutilization of platelets in patients with other MPD contributes to the thrombotic tendency noted in these patients. These results suggest another distinctive feature which separates CML from the other MPD. Platelet and fibrinogen kinetic studies are important in evaluating the pathophysiology of the thrombocytopenia or thrombocytosis of the myeloproliferative diseases as well as in investigating the physiology of hemostasis.