Effects of long-term postoperative dienogest use for treatment of endometriosis on bone mineral density

Objective This study was conducted to evaluate the effects of long-term postoperative dienogest (DNG) use for the treatment of endometriosis on bone mineral density (BMD). Study design Sixty reproductive-aged women who underwent conservative surgery for endometriomas and received postoperative DNG (2mg/day) for at least 12 months to prevent recurrence were analyzed. BMD was measured before and after DNG treatment by using dual energy X-ray absorptiometry, and changes in BMD were evaluated. Results Mean patient age was 30.5 years, and mean duration of DNG treatment was 18.6 months. BMD at the lumbar spine significantly decreased after the first 6 months (−2.2%), and 1year (−2.7%) of DNG treatment, compared to baseline. The proportion of women who had significantly decreased BMD at the lumbar spine after 1year was 75% (45/60). In addition, BMD at the femur neck also decreased significantly after 1year (−2.8%). BMDs after 2 years were not different from those after 1year at both sites in 24 women who received DNG for ≥2years. In addition, there were no differences in baseline characteristics between women who had significantly reduced BMD at the lumbar spine after 1year (N=45) and women who did not (N=15). Conclusion This study suggests that long-term postoperative DNG treatment might have an adverse effect on BMD in reproductive-aged women. Bone loss mostly occurs during the first 6 months of treatment with DNG. A clinical trial is warranted to establish the effects of long-term DNG treatment on bone mass.