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Thiazide Hypercalciuria Stone Prevention — ESENeph MCQ

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ModerateRenal Stone DiseaseThiazide Hypercalciuria Stone PreventionESENeph

A 42-year-old man presents with recurrent calcium oxalate kidney stones. 24-hour urine: calcium 9.5 mmol/day (elevated), oxalate 0.4 mmol/day (normal), citrate 2.5 mmol/day (normal), urine volume 2.8 L/day. Serum calcium 2.45 mmol/L, PTH 2.0 pmol/L (low-normal), 25-OH vitamin D 65 nmol/L. What is the most appropriate pharmacological intervention for stone prevention?

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Correct answer: C — Indapamide (thiazide-like diuretic)

This patient has absorptive hypercalciuria (elevated urinary calcium, normal serum calcium, low-normal PTH — excluding primary hyperparathyroidism). Thiazide/thiazide-like diuretics (hydrochlorothiazide, indapamide, chlorthalidone) are the evidence-based pharmacological treatment. They reduce urinary calcium excretion by enhancing proximal tubular calcium reabsorption secondary to mild volume contraction and by directly stimulating calcium reabsorption in the distal convoluted tubule via increased expression of TRPV5 channels. Multiple RCTs demonstrate significant reduction in stone recurrence. Dietary calcium should NOT be restricted as this paradoxically increases oxalate absorption and stone risk.

Reference: EAU 2023 – Urolithiasis Guidelines; AUA/CUA 2014 – Metabolic Stone Prevention