Hypocalcemia with hypophosphatemia is seen in: September 2006

Ans. C: Vitamin D dependent rickets-II In rhabdomyolysis due to crush injury, hypocalcemia and hyperphosphatemia may occur. Severe intravascular hemolysis may lead to a similar syndrome. Hyperphosphatemia alters calcium and phosphate ion solubility products, and calcium deposition in soft tissue may occur. The lower circulating concentrations of 1, 25 (OH)2D may fuher aggravate the hypocalcemia by impairing intestinal absorption of calcium. Hyperphosphatemic-induced hypocalcemia inhibits vitamin D synthesis and results in an increase in PTH secretion. Secondary hyperparathyroidism from long-term hyperphosphatemia is usually associated with renal insufficiency. Treatment should be directed towards the hyperphosphatemia in order to correct the hypocalcemia. Hypophosphatemia is more severe than hypocalcemia in vitamin D deficiency states because of the increased secretion of PTH, which is only paly active in elevating blood calcium but is capable of phosphaturia.