Secondary hyperparathyroidism due to Vit D deficiency shows:: (A) Hypocalcemia, (B) Hypercalcemia, (C) Hypophosphatemia, (D) Hyperphosphatemia
Answer is C. Vitamin D deficiency causes hypocalcemia and hypomagnesemia and decreases GI absorption of calcium and phosphate. Decreased serum Ca2+ will stimulate PTH secretion. The secondary hyperparathyroidism will bring the Ca2+ levels toward normal but cause phosphaturia. Thus serum phosphate loss will be fuher aggravated - hypophosphatemia. The level of calcium phosphate product is low, bone mineralization is impaired and demineralization is increased.