A 68-year-old man with osteoporosis is started on denosumab. He has uncorrected vitamin D deficiency (25-hydroxyvitamin D 12 ng/mL) and is not supplemented with calcium or vitamin D. Two weeks later he presents with perioral numbness, carpopedal spasm, and a positive Chvostek sign. The most likely explanation is:
- A Denosumab-induced nephrotoxicity causing hyperphosphatemia and secondary hypocalcemia
- B Denosumab-induced acute hypocalcemia due to abrupt inhibition of bone resorption in a patient with poor calcium reserves ✓
- C Anaphylactic reaction to denosumab causing vasomotor symptoms
- D Coincident primary hypoparathyroidism unmasked by denosumab therapy
Correct answer: B. Denosumab-induced acute hypocalcemia due to abrupt inhibition of bone resorption in a patient with poor calcium reserves
Explanation
Denosumab potently inhibits osteoclastic bone resorption. In patients with vitamin D deficiency and poor calcium reserves, the sudden drop in calcium release from bone can cause severe hypocalcemia. Vitamin D deficiency must be corrected before denosumab administration. Chvostek sign and carpopedal spasm are classic signs of hypocalcemia. Denosumab is not nephrotoxic.
Reference: Harrison's Principles of Internal Medicine, 20th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.