What is one reason why estrogen was not approved for treatment of osteoporosis?

Estrogen has been extensively studied in the context of osteoporosis, and one key reason it was not approved for treating this condition lies in evidence regarding its efficacy in reducing fracture risk among women diagnosed with osteoporosis. Although estrogen therapy is known to play a role in maintaining bone density and has been utilized in various settings, clinical studies have indicated that it does not provide a statistically significant reduction in the risk of fractures specifically in women who already have osteoporosis. Instead, the use of estrogen may be more beneficial in preventing bone loss or fractures in postmenopausal women who are at higher risk due to low estrogen levels rather than treating established osteoporosis.

This understanding is crucial because prescribing treatments, including estrogen, requires an assessment of the therapy's effectiveness in the target population. Given that fracture risk reduction is a primary outcome measure in osteoporosis management, demonstrating a clear benefit is essential for approval. In cases where the evidence does not support significant fracture risk reduction in women already diagnosed with osteoporosis, regulatory agencies are unlikely to approve such therapies for that specific indication.