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Recurrent calcium oxalate nephrolithiasis with hypercalciuria — MSRA MCQ

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ModerateNephrolithiasisRecurrent calcium oxalate nephrolithiasis with hypercalciuriaMSRA

A 51-year-old man is reviewed by his GP after his third calcium oxalate stone in 4 years. Analysis of a passed stone showed 85% calcium oxalate. Serum calcium is normal. Specialist metabolic assessment has identified hypercalciuria with normal urinary citrate. He drinks 2.5 to 3 litres of water daily but estimates his usual salt intake is about 9 g daily. Urology has asked the GP to optimise non-drug prevention before considering pharmacological prophylaxis. Which is the most appropriate next management plan?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Advise reducing salt intake to no more than 6 g daily before considering a thiazide

Explanation lettering: D = shown as A · E = shown as B · B = shown as C · C = shown as D · A = shown as E

This patient has recurrent predominantly calcium oxalate stones and hypercalciuria. NICE advises a daily salt intake of no more than 6 g for adults with renal or ureteric stones. For recurrent predominantly calcium oxalate stones with hypercalciuria, a thiazide can be considered only after sodium intake has been restricted to this level. Therefore, reducing his estimated 9 g daily salt intake is the appropriate next step before drug prophylaxis. A is incorrect because NICE specifies sodium restriction before considering thiazide therapy in this setting. C is plausible because potassium citrate may be considered for recurrent predominantly calcium oxalate stones, but it is not the targeted next intervention for identified hypercalciuria and does not replace sodium reduction. D is incorrect: adults should maintain, rather than restrict, normal dietary calcium intake of 700 to 1,200 mg daily. E overlooks a modifiable dietary risk factor despite adequate fluid intake.

Reference: NICE NG118: Renal and ureteric stones: assessment and management — Recommendations (Published 8 January 2019; last reviewed 26 February 2021) — https://www.nice.org.uk/guidance/ng118/chapter/Recommendations NICE NG118: Renal and ureteric stones: assessment and management — Overview (Published 8 January 2019; last reviewed 26 February 2021) — https://www.nice.org.uk/guidance/ng118