RAPID FIBRINOLYSIS, AUGMENTED HAGEMAN-FACTOR (FACTOR-XII) TITERS, AND DECREASED C1-ESTERASE INHIBITOR TITERS IN WOMEN TAKING ORAL-CONTRACEPTIVES

  • 1 January 1980
    • journal article
    • research article
    • Vol. 96  (5) , 762-769
Abstract
The use of OCA [oral contraceptives] was associated with multiple hemostatic abnormalities and an increased risk of thromboembolic disease. The changes were attributed to increased synthesis of various clotting factors and decreased titers of antithrombin III. Paradoxically, enhanced in vitro fibrinolytic activity is found in plasmas of women using OCA. Marked elevation of both procoagulant and antigenic HF [Hageman factor] titers is shown in plasmas of women using OCA, accompanied by a simultaneous decrease in plasma C.hivin.1-INH C1 esterase inhibitor concentration. Titers of plasma prekallikrein, high MW kininogen, plasma thromboplastin antecedent, and .alpha.2-plasmin inhibitor were unchanged. The rate of kaolin-assisted fibrinolysis was related directly to the titer of HF and inversely to C.hivin.1-INH concentration. Addition of human HF to normal plasma enhanced fibrinolytic activity to a degree similar to that observed in plasmas of women taking OCA. The increase in plasma HF concentration may participate in the phenomenon of enhanced in vitro fibrinolysis associated with OCA use, possibly augmented by diminished inhibitory control by C.hivin.1-INH. The relationship of the phenomena to the increased incidence of thrombosis is not known.