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Struvite Stones — ESENeph MCQ

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EasyRenal Stone DiseaseStruvite StonesESENeph

A 35-year-old woman presents with severe bilateral flank pain and CT-KUB shows bilateral staghorn calculi. Stone analysis shows struvite (magnesium ammonium phosphate). Urine culture grows Proteus mirabilis. What is the key underlying mechanism?

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Correct answer: C — Urease-producing organisms alkalize urine, promoting struvite crystal formation

Struvite (infection) stones are formed when urease-producing organisms (Proteus, Klebsiella, Pseudomonas) split urea into ammonia, raising urinary pH and promoting formation of magnesium ammonium phosphate crystals. These often form staghorn calculi. Definitive management requires stone removal (PCNL) and eradication of the underlying infection. Metabolic evaluation for other stone risk factors is also appropriate.

Reference: EAU 2024 – Urolithiasis Guidelines; NICE NG118 2019 – Renal/Ureteric Stones