Do Progestogens and Progesterone Reduce Bone Loss?

Long-term unopposed depot progestogens are currently used widely, mainly for contraception. Anxiety has recently arisen as to their implied role in the pathogenesis of osteoporosis. The reason for this has been the hypoestrogenic amenorrhoea that they can cause by hypothalamic suppression. On the other hand, progestogens have been shown from in vitro work, animal studies, and clinical trials to have bone trophic properties also. Review of the data available for the specific commonly used progestogens, such as depot medroxyprogesterone acetate, levonorgestrel implants, and the progestogen-only pill, provides inconclusive evidence as to the magnitude of the problem. Large long-term randomized controlled studies that examine bone turnover and densities are required to settle the issue. In the interim period, we should continue to use long-term progestogens as they provide an excellent method of contraception and are protective against endometrial cancer. However, we must be vigilant in women who become amenorrhoeic and have a low threshold for performing estradiol levels and bone density scans, giving add-back estrogen or withdrawing the drug where necessary.