3. Undergoing treatment with any of the following drugs: adrenocorticoid steroids (3 months or longer at anytime or > 10 days of treatment within the previous 12 months), anticonvulsant therapy (within the previous year), sodium fluoride (any history of treatment with fluoride), pharmacological doses of thyroid hormone (causing decline of TSH below normal), calcium supplementation of more than 1200 mg/d (within the preceding 3 months), bisphosphonates in the past, calcitonin (within the past six months), E therapy or treatment with a selective estrogen receptor modulator (within the past 6 months), parathyroid hormone (PTH) use in the past. Subjects with a clinical history of an osteoporotic fracture (vertebral, hip, or distal forearm) within the previous 3 years will also be excluded.