A 45-year-old man presents with bone pain, proximal muscle weakness, and difficulty walking. Serum 25-hydroxyvitamin D is 12 ng/mL (deficient). He has chronic kidney disease stage 3. Which form of vitamin D is the most appropriate initial therapy?
- A Calcitriol (1,25-dihydroxyvitamin D) ✓
- B Ergocalciferol (Vitamin D2)
- C Cholecalciferol (Vitamin D3)
- D Calcifediol (25-hydroxyvitamin D)
Correct answer: A. Calcitriol (1,25-dihydroxyvitamin D)
Explanation
In chronic kidney disease, the renal 1-alpha-hydroxylase enzyme is impaired, preventing conversion of 25(OH)D to active 1,25(OH)2D. Calcitriol bypasses this step. Cholecalciferol and ergocalciferol require renal activation and are ineffective here. Calcifediol still requires 1-alpha-hydroxylation.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.