Estrogen therapy and osteoporosis: principles & practice.

Postmenopausal osteoporosis is linked clearly to estrogen deprivation. Recent research has identified estrogen receptors in bone cells and in other organ systems that help to regulate bone remodeling and calcium homeostasis. Long-term use of estrogen in appropriate doses reduces the risk of hip fractures by 50% to 60% and the risk of vertebral deformation by 90%. This protective effect is maintained as long as estrogen is taken and adequate levels of biologically active estrogen are achieved. Thus, the type, dose, and route of administration of estrogen need to be individualized and the efficacy of treatment monitored by annual bone density testing and selective ultilization of biochemical bone markers. The ability of estrogen therapy to increase bone mass is enhanced by added androgens and progestin therapy, calcium supplementation, and exercise.