The comparative effects of a synthetic and a 'natural' oestrogen on the haemostatic mechanism in patients with primary amenorrhoea.

A synthetic and a natural oestrogen were administered alternately for three months to nine women with primary amenorrhoea using a randomized cross-over schedule. Measurements of haemostatic function were performed before and at the end of each treatment period. No significant change in haemostatic function was observed after treatment with the 'natural' oestrogen, oestriol succinate. In contrast, treatment with a synthetic oestrogen, ethinyloestradiol, caused shortening of the prothrombin time and an increase in plasma concentration of factor VII and plasminogen. These data support other observations in suggesting that natural oestrogens may have fewer potentially adverse effects on haemostatic function than synthetic oestrogen.