Changes of hemostatic variables during hormone replacement therapy

Hormone replacement therapy (HRT) is accompanied by many changes in the hemostatic system. Because several individual hemostatic variables have been suspected to be reasonable indicators of the hemostatic balance and because this balance is thought to play an important role in the pathogenesis of several diseases, careful examination of the changes in this system induced by HRT could be helpful, first to improve HRT and second to improve our understanding of mechanisms of cardiovascular disease. The effects of (several forms of) HRT on individual hemostatic variables are discussed in this article. The pattern that emerges is that HRT stimulates coagulation, inhibits anticoagulation, and stimulates fibrinolysis (partly by inhibition of fibrinolysis). There are, however, few data that give clear insight into the effects of HRT on hemostatic variables. Controlled randomized clinical studies are needed to evaluate further the effects of HRT on the hemostatic system, to understand the interplay between inflammation and coagulation (both pathways being affected by HRT), and to understand how HRT-associated changes are affected by differences in genetic background