Identifying individuals with elevated bone resorption who have osteoporosis in whom response to treatment is being monitored; Predicting response (as assessed by bone mass measurements) to Food and Drug Administration (FDA)-approved antiresorptive therapy in postmenopausal women; Assessing effectiveness of osteoporosis treatment including FDA-approved antiresorptive therapies in postmenopausal women, individuals with osteoporosis, Paget's disease of bone, and antiestrogen or selective estrogen therapies.