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Native Vitamin D Repletion Before Active CKD-MBD — ESENeph MCQ

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EasyChronic Kidney DiseaseNative Vitamin D Repletion Before Active CKD-MBDESENeph

A 55-year-old man with CKD G3b (eGFR 32 mL/min/1.73m2) has persistently elevated serum phosphate (2.3 mmol/L) despite sevelamer. His PTH is 55 pmol/L (elevated). 25-OH vitamin D is 30 nmol/L (deficient). Should native vitamin D be repleted before starting active vitamin D?

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Correct answer: A — Yes — replete native vitamin D (cholecalciferol) first, then reassess PTH

KDIGO 2024 CKD-MBD and NICE NG203 recommend correcting native vitamin D deficiency (25-OH vitamin D <50 nmol/L) with cholecalciferol BEFORE considering active vitamin D analogues (alfacalcidol/calcitriol). Many patients show PTH improvement with native vitamin D repletion alone. Starting active vitamin D in a vitamin D-deficient patient risks hypercalcaemia while leaving substrate deficiency uncorrected. The 1-alpha-hydroxylase enzyme in the kidney (which converts 25-OH-D to 1,25-OH2-D) retains some activity even in CKD G3b-4. Active vitamin D should be added only if PTH remains elevated AFTER 25-OH vitamin D is replete (>75 nmol/L) and phosphate is controlled.

Reference: KDIGO 2024 – CKD-MBD; NICE 2021 – NG203; UKKA 2015 – CKD-MBD