USMLE Q Bank Step 1- 219

A 64 year old woman complains of low back pain for 1 week. Her pain and tenderness is localized over the lumbar spine and exaggerated by movement. Her physician prescribes her a phosphonate drug.

What is the mechanism of action of this drug for this patient?

A- Decrease osteoclast activity

B- Increase osteoblast activity

C- Decrease parathormone activity

D- Increase vitamin D absorption

E- Increase urinary calcium reabsorption


This is most likely a case of osteoporosis. Phosphonates improve this condition through decreasing osteoclast activity. Biphosphonates are also the drug of choice in Paget’s disease of bone. Osteoblast activity is regulated by growth factors and parathyroid hormone. Calcium level of the blood is regulated by parathormone and vitamin D in addition to other factors.

The correct answer is A

2 thoughts on “USMLE Q Bank Step 1- 219”

  1. Thank you samir

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