Effect of combined therapy GnRH-a plus add-back tibolone on endocrine hormone levels and bone loss in endometriosis patients

Objective: This study is to compare the effect of combined therapy gonadotropin-releasing hormone agonist (GnRH-a) plus add-back tibolone on endocrine hormone levels and bone loss of endometriosis patients. Methods: Totally 100 endometriosis patients were enrolled. They were randomly divided into 1.25 mg tibolone group and 2.5 mg tibolone group, with 50 patients in each group. The levels of bone gla-protein (BGP) and endocrine hormone levels were measured before treatment and at 24 weeks of treatment. Bone mineral density (BMD) was measured before treatment, at 24 weeks of treatment, at 6 months and 12 months after drug withdrawal. Results: In both 1.25 mg tibolone group and 2.5 mg tibolone group, the serum endocrine hormone levels of estradiol, follicle-stimulating hormone, and luteinizing hormone at 24 weeks of treatment were significantly lower than those before treatment (P<0.05). Compared with before treatment, BGP level was significantly higher at 24 weeks of treatment in both groups (P<0.05). BMD of lumbar vertebra and femoral intertrochanteric at 24 weeks of treatment, at 6 months and 12 months after drug withdrawal were lower than those before treatment, but without significant difference. Furthermore, there were no significant differences in endocrine hormone levels, BGP or BMD between the two groups at all the time points. Conclusion: Combined therapy GnRH-a plus add-back tibolone can reduce bone loss and low dose tibolone can maintain bone density.