Section: USMLE

Question 20 of 60

20) A 75-year-old man presents to his physician with complaints of nocturia, urinary urgency, and a feeling that he could not completely empty his bladder. A digital rectal exam reveals a firm, enlarged prostate. A bone scan is ordered and shows positivity in multiple vertebral bodies. Elevation of which of the following substances would be most strongly associated with the development of bone lesions?