| Popis: |
Epidemiologic evidence suggests a protective effect of female sex hormones on the risk of thrombotic cardiovascular disease. To elucidate the possible mediating role of the haemostatic system, a variety of factors and inhibitors of coagulation and fibrinolysis have been studied in women before and after menopause as well as in postmenopausal women using oestrogen/progestagen preparations as hormone replacement therapy (HRT). Most consistent, increased blood viscosity, procoagulant activation and decreased fibrinolytic activity are discussed as potential mediating mechanisms. However, replacement of estradiol and progestagens failed to correct for these changes with the only exception of the fibrinolysic activity which was shown to be increased by hormone replacement therapy. Moreover, the induction of a postmenopausal state in premenopausal women by blocking the release of gonadotrophins is not associated with an increase in procoagulant activity but with a significant decrease of coagulatory reaction products. Evidence from studies in oral contraceptive users indicates a differential effect of oestrogens on the haemostatic system that might explain for most of the observed effects: While coagulatory activity is correlated with the oestrogen dose — exhibiting only minor activation in the HRT dose range — fibrinolysic activity appears to be independent of oestrogen dose and is increased even by very low oestrogen doses. HRT — due to the low oestrogen dose — might act beneficially on the progression of coronary heart disease by inducing fibrinolysic activity without concomitant coagulatory activation. |
