Which of the following is a consequence of vitamin D deficiency?

• A. Hypercalcemia
• B. Hypocalcemia
• C. Hyperphosphatemia
• D. Hypernatremia

Answer: (B)

Vitamin D’s role in calcium and phosphate absorption and bone health is being tested. When vitamin D is deficient, calcium absorption from the gut decreases, and serum calcium can drop. The body responds with increased parathyroid hormone, a compensatory mechanism that tries to pull calcium from bone and reduce calcium loss in the urine. Although PTH helps maintain calcium, overall calcium levels often fall, leading to hypocalcemia as a consequence of vitamin D deficiency. Hypercalcemia would be unlikely, since deficiency reduces calcium absorption and calcium levels; hyperphosphatemia is not typical because PTH promotes phosphate excretion and intestinal phosphate absorption is reduced with low vitamin D; hypernatremia is not related to vitamin D status.