The relation between plasma androstenedione and oestrone levels in untreated and corticosteroid-treated post-menopausal women.

Plasma oestrone (E1) and androstenedione (A) were measured in 96 untreated and 18 corticosteroid-treated post-menopausal women. Levels of both hormones were consistently lower in the steroid-treated cases, presumably due to suppression of ACTH secretion. There was a clear relationship between A and E1 levels in both groups and when the data were pooled they formed a continuous series with a curvilinear relationship going through the origin. This relationship could be described by an equation based on Michaelis-Menten kinetics, suggesting that the rate of A to E1 conversion is an inverse function of the plasma androstenedione level. The main determinant of plasma E1 was plasma A; body weight and age were of subsidiary importance. Secondary oestrogen deficiency may be a factor in the genesis of steroid-induced osteoporosis in post-menopausal women and oestrogen therapy may be indicated in this group of patients.