Comparison of the biochemical effects of testosterone and estrogen on bone markers in surgically menopausal women

Twenty-five women with a previous total abdominal hysterectomy with bilateral salpingo-oophorectomy (TAH BSO) were given estradiol 50 mg implants at baseline, followed at 16 weeks with the combination of estradiol 50 mg and testosterone 100 mg. Blood samples were taken at 8-weekly intervals over 32 weeks. Serum levels of estradiol, testosterone, sex hormone binding globulin (SHBG) and agents involved in skeletal growth (growth hormone (GH), insulin-like growth factor 1 (IGF-1), carboxy terminal pro-peptide of the 1 pro-collagen (PICP; a bone formation marker) and cross-linked carboxy terminal telopeptide (ICTP; a marker of bone resorption)) were measured. Serum PICP levels increased significantly after estradiol alone (p = 0.0032) but the addition of testosterone had no significant effects on bone markers GH and IGF-1. These biochemical changes confirm previous studies, which found that the addition of testosterone did not augment the effect of estradiol implants on bone mineral density. Although physiological hormone replacement therapy in oophorectomized women would include replacement of both estradiol and testosterone, this may not to be necessary for prevention of osteoporosis where adequate serum estradiol levels are reached.