Coagulation, oestrogen and the menopause.

The objective of oestrogen replacement therapy in the menopause is the prevention of pathology attributable to oestrogen lack. Care should be taken to ensure that such therapy is free from harmful side effects. To date, there have been no long-term longitudinal studies or clinical reports that have positively identified oestrogen usage in "normal" postmenopausal women, with inappropriate thrombosis directly attributable to an oestrogen-induced alteration in the coagulation mechanism. This is surprising since certain coagulation factors change and the peripheral blood flow decreases in the elderly, predisposing them to enhanced clot formation. There is also the well-documented (but controversial) association between oestrogens, oral contraceptives and thrombosis. Whether this paradox can be explained by differences in the type and/or potency of the oestrogens used in ORT, remains to be determined. At present it may be concluded that ORT per se does not place the postmenopausal women at greater risk from developing arterio-venous thrombosis.