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

OBJECTIVE: Oestrogens are used to inhibit growth in girls with constitutionally tall stature. We studied the changes in different hormones that accompany such therapy. SUBJECTS AND METHODS: In this longitudinal study we examined the levels of total insulin-like growth factor-I (IGF-I), free thyroxine (FT(4)), thyrotrophin (TSH), testosterone, dehydroepiandrosterone sulphate (DHEA-S), cortisol and prolactin in two groups of girls receiving ethinyloestradiol at a dose of either 0.1mg daily (group A, n=22) or 0.2mg daily (group B, n=36). Hormonal measurements were performed at start of therapy and after 3, 6 and 12 months. RESULTS: In both groups the levels of IGF-I, testosterone and DHEA-S were reduced while the concentrations of cortisol and prolactin were increased. The pituitary-thyroid axis was not significantly affected by this therapy. The girls receiving 0.2mg ethinyloestradiol daily had lower IGF-I levels after 12 months of therapy and had higher serum prolactin concentrations than the girls treated with 0.1mg daily. The reduction in predicted height and the advancement in bone age were similar in both groups. CONCLUSIONS: Therapy with pharmacological doses of ethinyloestradiol changes the levels of several hormones including IGF-I, testosterone, DHEA-S, prolactin and cortisol but the role of the respective changes in the inhibition 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.

Low thyroxinaemia occurs in the majority of very preterm newborns.

UNLABELLED: Transient hypothyroxinaemia with normal thyroid stimulating hormone (TSH) levels is a well-known condition in preterm neonates and is generally assumed to be a harmless epiphenomenon of prematurity. This assumption is, however, based on studies that included very few neonates with a gestational age (GA) below 30 weeks. We therefore measured serum free thyroxine (FT4) and serum TSH on days 1 and 14 in 263 neonates with a GA between 26 and 41 weeks. In 13 infants (5%), transient hypothyroidism (low FT4 and TSH >20 mU/l on day 14) was found. In the remaining 250 patients FT4 on days 1 and 14 but not TSH correlated positively with GA. In neonates with a GA of 35-41 weeks, FT4 increased postnatally to levels within or above the normal adult range. In contrast, in the very preterm group (26-31 weeks) the already low FT4 levels declined to values significantly below the range observed in term neonates. A significant proportion of these neonates had FT4 levels within the hypothyroid range. There was no difference in thyroid function between neonates treated with povidone-iodine or chlorhexidine. CONCLUSION: Very preterm neonates have FT4 levels on day 14 that are much lower than is generally assumed while TSH remains in the normal range. We therefore propose to measure FT4 in all preterms with a GA below 33 weeks, during the 2nd week of life.