Which vitamin deficiency is most closely linked to CKD-related bone mineral disorders?

• A. Vitamin C
• B. Vitamin D
• C. Vitamin B12
• D. Vitamin A

Answer: (B)

The key idea here is that vitamin D is central to calcium and bone homeostasis, and kidney disease disrupts its activation. In CKD, the kidneys lose much of their ability to convert 25-hydroxyvitamin D into the active form, 1,25-dihydroxyvitamin D (calcitriol). This drop reduces calcium absorption from the gut, promoting hypocalcemia and prompting secondary hyperparathyroidism, which drives bone turnover changes and renal osteodystrophy—the bone mineral disorder seen with CKD. Complicating this, CKD often raises phosphate levels and FGF23, which further suppresses the enzyme that makes active vitamin D, deepening the deficiency. So, a deficiency of vitamin D directly underpins the mineral imbalance and bone problems characteristic of CKD-MBD. Other vitamins, like vitamin C, B12, or vitamin A, don’t have the same direct, central link to the calcium-phosphate–PTH axis and bone mineralization seen in CKD, even though they have other roles in health.