Letter: Effect of natural oestrogens on coagulation.

The effect of oestrogen on megakaryocyte differentiation and platelet counts in vivo

“…Through its ability to alter megakaryocytic differentiation and proplatelet formation it is possible that oestrogen could modify the number of platelets available to form thrombi in this mouse model. However, while oestrogen treatment in humans has been shown to alter platelet number [8,9] other studies have failed to note any change [19]. These discrepancies coupled with differences in the routes of administration make the relevance of our results to the clinical setting unclear.…”

“…Similarly, human studies have not published data relating 0167 oestrogen treatment to changes in MK and platelet number 8,9. Therefore, we examined the effect of smaller supraphysiological doses of 17-h oestradiol and circulating oestrogen concentrations on megakaryocytopoesis and related this to circulating platelet numbers in mice in vivo.…”

The Effects of an Increase in Endogenous Oestrogen on the Haemostatic Mechanism

“…1954, Pechet and Alexander 1961, Talbert and Langdale 1964, and plasminogen levels (Bonnaret a!. 1970) and it is reported to reduce levels of antithrombin III (Notelovitz andGreig 1976, Peterson eta!. 1970).…”

Platelet activation status decreases after menopause

“…We also identified a controversial reduction of plasma fibrinogen after menopause. Investigators have long been trying to establish whether estrogen replacement therapy results in increased fibrinogen concentration [53], but no consensus has been reached [54].…”