Stone Prevention Intervention Prioritisation — ESENeph MCQ

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ModerateRenal Stone DiseaseStone Prevention Intervention PrioritisationESENeph

A 50-year-old man with CKD G3b and recurrent calcium oxalate stones has completed a metabolic evaluation showing: high urinary calcium, high urinary oxalate, low urinary citrate, and low urine volume. He has multiple modifiable risk factors. In what order should interventions be prioritised?

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Correct answer: B — (1) High fluid intake (>2.5 L/day); (2) Dietary sodium restriction (<2 g/day – reduces calciuria); (3) Normal dietary calcium (1000-1200 mg/day – binds gut oxalate); (4) Reduce dietary oxalate; (5) Potassium Citrate (for hypocitraturia); (6) Thiazide (for persistent hypercalciuria) – lifestyle modifications precede pharmacological therapy

EAU 2024 and NICE NG118 recommend a stepwise approach: lifestyle modifications first, then medications if needed. The priority order reflects evidence strength and safety: (1) fluid intake is the single most impactful and safest intervention; (2) sodium restriction (reduces calciuria via shared proximal tubular transport – every 100 mmol Na reduction decreases urinary Ca by ~0.5 mmol); (3) normal dietary calcium (paradoxically protective – gut calcium binds dietary oxalate, reducing absorption); (4) reduce oxalate-rich foods; (5) Potassium Citrate for hypocitraturia (increases urinary citrate and pH); (6) Thiazide for persistent hypercalciuria despite dietary measures. This stepwise approach maximises benefit while minimising unnecessary medication.

Reference: EAU 2024 – Urolithiasis; NICE NG118 2019