CHANGES IN SEX HORMONE-BINDING GLOBULIN PLASMA-CONCENTRATIONS INDUCEDBY BODY-WEIGHT AND ESTROGEN STATUS IN PERIMENOPAUSAL YEARS

A cross-sectional study was conducted on 562 healthy perimenopausal wo men, with a mean age of 52.6 years, to follow perimenopausal changes i n sex hormone-binding globulin (SHBG) plasma levels during the perimen opausal years. According to menstrual history and follicle-stimulating hormone (FSH) levels, 398 women were considered postmenopausal, and 1 64 were premenopausal. Women with a body mass index (BMI) of <25 were considered to be of average weight, and those with a BMI greater than or equal to 25 were thought to be overweight. To study the effect of o ral hormone replacement therapy, 153 women in the postmenopausal group were given 0.625 mg/day of oral conjugated estrogen plus medroxyproge sterone acetate, 10 mg/day, for 12 days every 3 months. SHBG levels we re assayed at baseline and after 12 months of therapy. SHBG was positi vely associated with 17 beta-estradiol plasma levels (r = 0.09, p < 0. 05), and there was a strong negative correlation with BMI (r = -0.27, p < 0.001). After menopause, SHBG plasma levels dropped significantly (p < 0.05), but only in lean women. Similarly, hormone replacement the rapy increased SHBG plasma levels in lean postmenopausal women (p < 0. 001) but not among overweight treated women. These findings indicate t hat circulating estrogens are the main factor in SHBG metabolism in le an women, while obesity apparently abolishes the hormonal influence of ovarian estrogen and of hormone replacement therapy.