Heterogeneous mechanisms responsible for reduced fibrinolytic capacity in patients with a history of venous thrombosis

The Plasma Levels of Prostanoids and Plasminogen Activator Inhibitor-1 in Primary and Secondary Thrombocytosis

An elevated platelet count is a common finding in both hospitalized and ambulatory patients. Thrombosis and bleeding complications are more frequently observed in patients with clonal thrombocytosis than secondary thrombocytosis. The aim of this study was to investigate the behaviors of plasminogen activator inhibitor type 1 (PAI-1), the inhibitor of fibrinolysis; and thromboxane A2 and 6-keto-PGF1 α, the products of endoperoxides, in 16 patients affected with clonal thrombocytemia as compared with 16 patients with reactive thrombocytosis and 15 normal controls. In the clonal thrombocytemia group, plasma levels of PAI-1 antigen and activity were significantly higher than both reactive thrombocytosis and control group. Plasma levels of 6-keto-PGF1α were significantly higher in the clonal thrombocytemia group than the other two groups and also higher in the reactive thrombocytosis group than the control group, which was also significant. This study confirms that arachidonate metabolism is frequently deranged in patients with thrombocytosis and hypofibrinolysis due to increased PAI-1 plasma levels as shown in the clonal thrombocytosis group. This may explain the thrombotic tendency in myeloproliferative disorders.

Coagulation and Fibrinolysis During the First Year of Immunosuppressive Treatment in Renal Transplantation: Correspondence Between Hypercoagulable State and Steroid Therapy

An increased incidence of thromboembolic complications has been reported after kidney transplantation, and hypercoagulability has been associated with immunosuppressive treatment, specifically with Cyclosporin A. Hypercorticism due to prolonged steroid therapy or to Cushing's disease has been associated with a similar hypercoagulable state and thrombotic risk. The aims of this study were first to evaluate coagulation and fibrinolytic behavior in 27 patients at different times during the first year after renal transplantation and then to compare the same patients' coagulation and fibrinolytic findings 1 month after transplantation with those of a normal control group and a group of Cushing's patients. Compared with normal controls, renal transplant patients and Cushing's patients showed a similar hypercoagulable and hypofibrinolytic state, with a significant shortening in activated partial thromboplastin time and increase in factor VIII-von Willebrand factor complex, tissue plasminogen activator concentration, and plasminogen activator inhibitor activity and concentration. Other test results in the two groups showed no differences. The same abnormalities were present in the renal transplant group for the entire period of study. Our results suggest that a hypercoagulable and hypofibrinolytic state persists almost 1 year after renal transplantation and that these abnormalities are very similar to those present in Cushing's disease. Steroid treatment seems to play a key role in determining thromboembolic risk after renal transplantation. Key Words: Renal transplantation-Hypercoagulable state—von Willebrand factor-Hypofibrinolysis-Plasminogen activator inhibitor-Steroid therapy-Cyclosporin A.

Plasma levels of thrombin-activatable fibrinolysis inhibitor in primary and secondary thrombocytosis

An elevated platelet count is a common finding in both hospitalized and ambulatory patients. Thrombosis and bleeding complications are more frequently observed in patients with clonal thrombocytosis than secondary thrombocytosis. The aim of this study was to investigate the behaviors of thrombin-activatable fibrinolysis inhibitor (TAFI) activity, the inhibitor of fibrinolysis, and also prothrombin time (PT), active partial thromboplastin time, and D-dimer and fibrinogen levels in 21 patients affected with clonal thrombocytemia as compared with 21 patients with reactive thrombocytosis and 21 healthy controls. In the clonal thrombocytemia group, plasma levels of TAFI activity were significantly higher than in both the reactive thrombocytosis and the control group. Plasma levels of leukocyte and platelet counts were significantly higher in the clonal thrombocytemia group than in the other two groups and also higher in the reactive thrombocytosis group than in the control group, which was also significant. Fibrinogen and D-dimer levels were higher in patients than in the control group but showed no significant difference between the clonal and secondary thrombocytosis groups. Plasma levels of PT and aPTT were higher in secondary thrombocytosis group than the clonal thrombocytosis group. The results of this study showed for the first time that TAFI activity is increased in patients with clonal thrombocytosis. These increased levels in clonal thrombocytosis can be considered a factor to explain the thrombotic tendency in myeloproliferative disorders.