Mass General - Division of Clinical Research

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: 1. Female aged > 45 years 2. Postmenopausal by either of the following criteria: 1. > 36 since last spontaneous menses 2. > 36 months since hysterectomy, plus serum FSH > 40 units / liter if < 60 years

• renal disease (stage 4 CKD) - elevated blood PTH (intact PTH > 77 pg/ml). - serum 25-OH vitamin D < 20 ng/ml - major psychiatric disease that in the opinion of the investigator would preclude the subject from providing adequate informed consent or completing the protocol procedures. - excessive alcohol use or substance abuse that would preclude the subject from providing adequate informed consent or completing the protocol procedures. - known congenital or acquired bone disease other than osteoporosis. - exposure to oral bisphosphonates within the past 3 months, denosumab in the last 12 months, intravenous bisphosphonates within the past 24 months. - exposure to estrogens, SERMs, or calcitonin, oral or parenteral glucocorticoids for more than 14 days in the past 2 months. - any prior exposure to romosozumab.