Decreasing serum levels of sex hormone-binding globulin around the menopause and temporary relation to changing levels of ovarian steroids, as demonstrated in a longitudinal study

Abstract

Blood samples collected longitudinally in 17 women over a period of 3 years, starting 11/2 years before the menopause, were assessed for sex hormone-binding globulin (SHBG), 17 beta-estradiol (E2), progesterone, and total testosterone. A slight (7.2%) decrease in mean SHBG from 4.25 +/- 1.67 (standard deviation) mg/l to 3.95 +/- 1.61 mg/l was observed within the 6-month period encompassing the menopause. More specifically, the decrease appeared to commence at the menopause and to become clearly significant (P = 0.01) some 2 to 6 months later. During the subsequent year, a further decrease to 3.64 +/- 1.42 mg/l was observed, amounting to a total decrease in mean SHBG by 14.4% (P less than 0.001). Of the hormones, only E2 exhibited a marked decrease (P less than 0.01) within this same 6-month period. The changes in SHBG during the 6-month transition period from premenopause to postmenopause correlated significantly (P = 0.013) only with those of E2. It is concluded that decreasing E2 levels appear to play a significant role in the downward modulation of SHBG levels commencing at the menopause.