HIGH PLASMA-LEVELS OF PLASMINOGEN-ACTIVATOR INHIBITOR-1 (PAI-1) IN POLYCYTHEMIA-VERA AND ESSENTIAL THROMBOCYTHEMIA ARE ASSOCIATED WITH THROMBOSIS

We attempted to determine if a hypercoagulability state exists in pati ents with polycythemia vera (PV) and essential thrombocythemia (ET). W e studied the hematocrit level, platelet count, use of any antiaggrega nt drugs, thrombotic or bleeding accidents and plasma levels of antith rombin III, protein C, total protein S, free protein S, vWF:Ag (Von Wi llebrand's factor related antigen), thrombin-antithrombin complexes, D -dimer, fibrinolytic activity, tissue plasminogen activator, plasminog en and PAI-1 in 33 patients (19 with ET and 14 with PV). PAI-1 plasma concentration was significantly higher in, both ET and PV patients tha n in the control group, and were higher in those patients with previou s thrombotic episodes than in asymptomatic patients or with previous b leeding episodes. Increasing age was associated to more thrombotic epi sodes while younger patients presented with more hemorrhagic complicat ions. A linear correlation between platelet count and PAI-1 levels in PV patients (r=0.44, p<0.05) and ET patients (r=0.30, p<0.05) was foun d. Fibrinolytic activity in patients with ET was significantly decreas ed when compared to the control group. A hypofibrinolytic state could be an additional factor which could be used as a predictive index of t he thrombotic or bleeding tendency in each patient.