Association of Sex Hormones and Adiposity with Plasma Levels of Fibrinogen and PAI-1 in Postmenopausal Women

Abstract

Blood levels of the clotting factor fibrinogen and tissue plasminogen activator inhibitor-1 (PAI-1), a primary inhibitor of fibrinolysis, have been positively linked to risk of coronary heart disease. The authors have reported previously that plasma fibrinogen appears to rise after menopause and to be reduced with use of postmenopausal hormonal therapy. There is also evidence to suggest that sex hormones may influence PAI-1. To examine whether plasma fibrinogen and PAI-1 antigen levels differ among older postmenopausal women according to use of hormone therapy and by blood level of estrogen and androgens, these variables were assessed among 277 healthy women aged 65-82 years, one half of whom were receiving therapy. The study population was drawn from the Study of Osteoporotic Fractures, Pittsburgh, Pennsylvania, during 1986-1988. Overall, results showed median PAI-1 levels to be lower on average with oral and transdermal use of hormone therapy (25.0 vs. 33.5 ng/ml, p < 0.01) and mean fibrinogen levels to be lower (279 vs. 295 mg/dl, p < 0.02) with use of oral estrogen (but not transdermal) therapy compared with women not receiving therapy. Among women not receiving therapy, PAI-1 and fibrinogen levels were not related to endogenous sex hormone levels, with the exception of a modest positive relation between PAI-1 and serum estrone concentrations (rs = 0.29). In addition, a markedly higher PAI-1 level was found for women with a preponderance of upper body fat, independent of obesity. In sum, results showed that older women receiving postmenopausal hormone therapy had more favorable plasma levels of the hemostatic factors PAI-1 and fibrinogen than did those not receiving therapy, which can be explained in large part by differences between the two groups in obesity and body fat distribution.