A 70-year-old man with stage 5 CKD on haemodialysis three times weekly is found to have serum calcium 8.0 mg/dL, phosphate 7.2 mg/dL, PTH 820 pg/mL, and 25-OH vitamin D 12 ng/mL. Which treatment should be initiated FIRST according to KDIGO 2017 CKD-MBD guidelines?

• A Calcitriol (active vitamin D)
• B Cinacalcet
• C Phosphate binder (calcium-free, e.g. sevelamer) ✓
• D Cholecalciferol (native vitamin D)

Explanation

KDIGO 2017 CKD-MBD guidelines prioritise correction of hyperphosphataemia as the first step in managing secondary hyperparathyroidism in dialysis patients, as elevated phosphate is a key driver of PTH secretion and cardiovascular calcification. Calcium-free phosphate binders (sevelamer, lanthanum) are preferred over calcium-containing binders to avoid further calcium loading. Once phosphate is controlled, active vitamin D analogues and/or cinacalcet can be added for persistent elevated PTH. Calcitriol without prior phosphate control can worsen hyperphosphataemia.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.