Haemostatic changes in tall girls treated with high doses of ethinyloestradiol.

Haemostasis was studied in 8 tall girls during treatment with high doses of synthetic oestrogens for a period of 1 to 28 months. The girls received 0.5 mg ethinyloestradiol daily from day 1 to day 25 and 15 mg norethisteron daily from day 21 to day 25. All were without clinical signs of thromboembolism. Factors of the prothrobmin complex were significantly elevated in the tall girls compared to healthy controls of the same age. Fibrinogen was also significantly elevated. Factor VIII-related antigen was significantly higher in the tall girls and the ratio between factor VIII activity and factor VIII-related antigen was significantly decreased in the tall girls, as compared to the controls. Thrombin time was significantly shortened. Tests of primary haemostasis showed an increased tendency for thrombocytes to adhere to glass and to aggregate spontaneously and after stimulation with ADP or collagen. Whether these in vitro signs of hypercoagulability indicate an enhanced risk of throbmoembolic complications in tall girls treated with high doses of oestrogens remains to be established. However, these girls should be watched carefully for clinical signs of throbmoembolic complications during treatment.