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A 25- year old man is diagnosed with Vitamin-D resistant rickets. Aside from high-dose Vitamin D and oral phosphate, an additional therapeutic approach might be to use which of the following drugs? (AIIMS Nov 11)
Ans. A Calcitriol
- Vitamin D is hydroxylated to 25-OH D3 (calcifediol). Calcifediol is then hydroxylated in the kidney to the most active form of vitamin D, which is 1, 25-dihydroxyvitamin D (calcitriol).
- Given as a drug, calcitriol rapidly elevates serum Ca2+ levels by enhancing the intestinal absorption of Ca.
- It is indicated in vitamin D deficiency, particularly in patients with chronic renal failure or renal tubular disease, hypoparathyroidism, osteomalacia, and rickets, Serum phosphate levels usually increase with prolonged treatment.