A longitudinal evaluation of the effect of two doses of tibolone on bone density and metabolism in early postmenopausal women

Tibolone, a steroid with tissue-specific activities, can reduce the bone resorption that takes place after the menopause. The present calcium-controlled, 2-year study aimed to evaluate the effect of two doses of oral tibolone, 1.25 mg and 2.5 mg, on bone loss in early postmenopausal women. The subjects were randomly allocated to one of the three groups, namely tibolone 2.5 mg (n = 30), tibolone 1.25 mg (n = 30) and a control group (n = 30). All subjects received 1000 mg of calcium per day. In the control group, vertebral and femur bone mineral density (BMD) decreased significantly (p < 0.05) after 12 and 24 months. In both tibolone groups, vertebral and femur BMD increased significantly (p < 0.05) increased after 12 and 24 months. In the control group, bone turnover markers (urinary excretion of hydroxyproline/creatinine and plasma osteocalcin levels) remained constant, while in both tibolone groups these markers showed similar significant decreases (p < 0.05) after 12 and 24 months. After 24 months, body weight increased in the control group (p < 0.05), while smaller increments were evident in the tibolone groups. Symptom scores in the control group did not show any significant modification during the study. In contrast, the administration of 2.5 mg tibolone was significantly (p < 0.05) effective in reducing hot flushes and other symptoms. The tibolone 1.25 mg group yielded similar results (even if it was proportionally less efficient) to the higher dose. It is concluded that tibolone is effective, even at lower doses, in relieving climacteric symptoms and preventing a decrease in spine and femur BMD in early postmenopausal women.