Transdermal 17 beta-estradiol combined with oral progestogen increases plasma levels of insulin-like growth factor-I in postmenopausal women.

In order to evaluate the effect of postmenopausal estrogen replacement therapy on the plasma levels of the insulin-like growth factor-I (IGF-I) 12 postmenopausal women aged 44 to 59 years were studied. The control group consisted of 15 healthy premenopausal women aged 20-44 years. In the postmenopausal women the plasma levels of IGF-I, gonadotrophins and sex hormones were determined before and after 3 and 6 months cyclic replacement therapy with transdermal 17 beta-estradiol (E2 100 micrograms patches applied twice weekly) combined with oral chlormadinone acetate (2 mg daily for 7 days in each cycle). Basal levels of estradiol (E2), IGF-I, dehydroepiandrosterone sulphate (DHEA-S), testosterone and androstenedione were lower, but gonadotropin levels were higher in postmenopausal than in premenopausal women. In all the women studied age was inversely correlated with IGF-I levels (r = -0.793, p less than 0.001) and with DHEA-S concentrations (r = -0.435, p less than 0.02). In postmenopausal women transdermal estradiol administration restored the circulating E2 levels to the early follicular range and increased the IGF-I levels (from 76.4 +/- 9.2 micrograms/l to 141.8 +/- 20.8 micrograms/l; p less than 0.01). Transdermal estradiol decreased gonadotrophin levels without changes in concentration of DHEA-S, testosterone, androstenedione and SHBG. In postmenopausal women before and during replacement therapy a positive correlation was found between estradiol and IGF-I concentrations (r = -0.439, p less than 0.01). These results suggest that cyclic replacement therapy with transdermal 17 beta-estradiol in combination with chlormadinone acetate given orally increase the plasma levels of IGF-I in postmenopausal women.