DIFFERENTIAL-EFFECTS OF ORAL CONJUGATED ESTROGENS AND TRANSDERMAL ESTRADIOL ON INSULIN-LIKE GROWTH-FACTOR-1, GROWTH-HORMONE AND SEX-HORMONEBINDING GLOBULIN SERUM LEVELS

In postmenopausal women oval ethinylestradiol causes a reduction in ci rculating insulin-like growth factor 1 (IGF-1) and an increase in seru m growth hormone levels. There are no data on the effect of conjugated estrogens, the preparation most often used in estrogen replacement tr eatment (ERT), on these parameters. We evaluated serum ICF-1 and growt h hormone levels, together with the levels of sex hormone binding glob ulin (SHBG), an indicator of estrogen hepatocellular action, before an d after 6 months of ERT in two comparable groups of post-menopausal wo men. Sixteen women were treated with oval conjugated estrogens, 0.625 mg/day, and 14 with transdermal estradiol, 0.05 mg/day. ln the women t reated with. oral conjugated estrogens, an increase in SHBG (p < 0.001 ), a decrease in IGF-1 (p < 0.001) and an increase in growth hormone ( p < 0.05) serum levels were observed. No such effects were seen with t he use of transdermal estradiol, devoid of hepatocellular effects. Und oubtedly, oral conjugated estrogens, 0.625 mg/day, through a hepatocel lular effect, cause marked modifications in the IGF-1/growth hormone a xis, which may have clinical relevance. For instance, the decreased IG F-l level, together with the increased level of SHBG, might provide so me explanation of the favorable epidemiological data on breast cancer risk in women receiving oval conjugated estrogens.