A 62-year-old woman presents to your office after being diagnosed with osteoporosis by her primary care physician. Her T-score is −4.2 at the lumbar spine. Further testing reveals a serum calcium level of 11 mg/dL (normal 8.5–10.5 mg/dL), a phosphate level of 1.7 mg/dL (normal 2.5–4.8 mg/dL), an intact parathyroid hormone level of 83 pg/mL (normal 15–75 pg/mL), and elevated urinary calcium levels. She denies any previous fractures. She reports fatigue and difficulty concentrating. She denies any history of neck irradiation or family history of thyroid or parathyroid disease. She has no significant past medical or surgical history. She has no known allergies. She occasionally takes ibuprofen for joint pain in her hands. She is a retired schoolteacher who is physically active and enjoys traveling. On review of systems, the patient reports constipation and occasional depressed mood. Physical examination is unremarkable; her neck is supple without masses or adenopathy.