Which vitamin D analog is commonly used to treat CKD-related secondary hyperparathyroidism, and what must be monitored?

• A. Calcitriol or paricalcitol; monitor calcium, phosphate, and PTH
• B. Ergocalciferol; monitor vitamin D levels only
• C. Calcitonin; monitor calcium
• D. Cholecalciferol; monitor liver enzymes

Answer: (A)

In CKD-related secondary hyperparathyroidism, the kidney can’t activate vitamin D, so treatment uses active vitamin D analogs that directly stimulate vitamin D receptors to suppress parathyroid hormone (PTH) production. Calcitriol and paricalcitol are such analogs; they bypass the need for renal activation and effectively lower PTH. However, they increase intestinal absorption of calcium (and can affect phosphate), so you must monitor serum calcium, serum phosphate, and PTH to keep them in target ranges and adjust dosing to avoid hypercalcemia or hyperphosphatemia. Ergocalciferol and cholecalciferol are precursors that require activation in the kidneys and are less reliable for managing SHPT in advanced CKD; monitoring vitamin D levels alone doesn’t address the mineral balance risk. Calcitonin is not a vitamin D analog, and monitoring liver enzymes isn’t the primary concern here.