Idiopathic Hypercalciuria — ESENeph MCQ

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HardRenal Stone DiseaseIdiopathic HypercalciuriaESENeph

A 48-year-old man with recurrent calcium oxalate stones has a 24-hour urine showing elevated calcium excretion (10 mmol/day) with normal serum calcium and PTH. What is the most appropriate long-term pharmacological prevention?

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Correct answer: C — Thiazide diuretic (e.g. Indapamide or Bendroflumethiazide)

Idiopathic hypercalciuria (high urinary calcium with normal serum calcium and PTH) is a common metabolic abnormality in calcium stone formers. Thiazide diuretics reduce urinary calcium excretion by increasing distal tubular calcium reabsorption. Combined with high fluid intake, dietary sodium restriction, and adequate dietary calcium (not supplemental), thiazides significantly reduce stone recurrence. Loop diuretics increase urinary calcium and worsen stone risk.

Reference: EAU 2024 – Urolithiasis Guidelines