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Kidney stone prevention — ABIM Board MCQ

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ModerateNephrologyKidney stone preventionABIM Board

A 46-year-old has recurrent calcium oxalate stones. Twenty-four-hour urine shows low volume and hypercalciuria, and dietary sodium intake is high. Serum calcium is normal. Which initial prevention plan is appropriate?

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

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Correct answer: E — Increase urine volume, restrict sodium and maintain normal dietary calcium

The best answer is “Increase urine volume, restrict sodium and maintain normal dietary calcium”. Higher urine volume lowers supersaturation, and sodium restriction reduces urinary calcium. Normal dietary calcium binds oxalate in the gut; severe calcium restriction can increase oxalate absorption. Vitamin C can raise oxalate and loop diuretics increase calciuria. A thiazide may be added if hypercalciuria persists.

Reference: AUA Medical Management of Kidney Stones Guideline: https://www.auanet.org/documents/Guidelines/PDF/clinical-guidance/Medical-Management-of-Kidney-Stones.pdf