Hormonal changes during the first year of oestrogen treatment in constitutionally tall girls

Objective: Oestrogens are used to inhibit growth in girls with constitution ally tall stature. We studied the changes in different hormones that accomp any such therapy. Subjects and methods: In this longitudinal study we examined the levels of total insulin-like growth factor-I (IGF-I), free thyroxine (FT4), thyrotrop hin (TSH), testosterone, dehydroepiandrosterone sulphate (DHEA-S), cortisol and prolactin in two groups of girls receiving ethinyloestradiol at a dose of either 0.1 mg daily (group A, n = 22) or 0.2 mg daily (group B, n = 36) . Hormonal measurements were performed at start of therapy and after 3, 6 a nd 12 months. Results: In both groups the levels of IGF-I, testosterone and DHEA-S were r educed while the concentrations of cortisol and prolactin were increased, T he pituitary-thyroid axis was not significantly affected by this therapy, T he girls receiving 0.2 mg ethinyloestradiol daily had lower IGF-I levels af ter 12 months of therapy and had higher serum prolactin concentrations than the girls treated with 0.1 mg daily. The reduction in predicted height and the advancement in bone age were similar in both groups. Conclusions: Therapy with pharmacological doses of ethinyloestradiol change s the levels of several hormones including IGF-I, testosterone, DHEA-S, pro lactin and cortisol but the role of the respective changes in the inhibitio n of growth is not clear. The suppression of DHEA-S levels by 40% suggests that the ovaries contribute significantly to the production of this hormone in pubertal girls.