Osteomalacia is associated with deficiency of which vitamin?

• A. Vitamin A
• B. Vitamin D
• C. Vitamin K
• D. Vitamin C

Answer: (B)

Osteomalacia results from defective mineralization of the bone matrix in adults, most commonly due to insufficient vitamin D. Vitamin D is essential for absorbing calcium and phosphate from the gut and for maintaining appropriate serum calcium and phosphate levels. When vitamin D is deficient, calcium (and often phosphate) absorption falls, leading to secondary changes such as elevated parathyroid hormone. This hormonal response increases bone turnover but impairs proper mineralization of the osteoid, producing soft, poorly mineralized bones characteristic of osteomalacia, with bone pain and a risk of fractures.

Other vitamins play different roles and don’t typically cause osteomalacia when deficient: vitamin A is more tied to remodeling and growth control, vitamin K is important for activating osteocalcin but deficiency doesn’t cause the classic mineralization defect, and vitamin C deficiency leads to defective collagen synthesis (scurvy) with bone and gum symptoms but not the mineralization problem seen in osteomalacia.