A 58-year-old postmenopausal woman on long-term prednisone (10 mg daily for 2 years for rheumatoid arthritis) has a DXA T-score of -2.6 at the lumbar spine. The primary cellular mechanism responsible for glucocorticoid-induced osteoporosis is:

• A Increased osteoclast lifespan and activity via RANKL upregulation
• B Osteoblast and osteocyte apoptosis with reduced bone formation ✓
• C Direct inhibition of calcium absorption causing secondary hyperparathyroidism
• D Increased renal phosphate wasting leading to impaired mineralization

Explanation

Glucocorticoids directly induce apoptosis of osteoblasts and osteocytes, profoundly suppressing bone formation as the dominant mechanism. They also increase osteoclast lifespan, but the primary defect is reduced bone formation. They reduce intestinal calcium absorption, but this is a secondary contributor, not the main cellular mechanism. Phosphate wasting is not a feature.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.