∙ All postmenopausal women who are prescribed romosozumab by their treating physicians, meet the FDA-defined indication for romosozumab, and who are not at increased risk for a bone marrow aspirate or bone biopsy will be offered enrollment. The FDA approved indication for romosozumab is: the treatment of osteoporosis in postmenopausal women at high risk for fracture, defined as a history of osteoporotic fracture, or multiple risk factors for fracture; or patients who have failed or are intolerant to other available osteoporosis therapy. Volunteers must be:

• Female aged \> 45 years

• Postmenopausal by either of the following criteria:

‣ \> 36 since last spontaneous menses

⁃ \> 36 months since hysterectomy, plus serum FSH \> 40 units / liter if \< 60 years