Struvite stones — RACP Paediatrics MCQ

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ModerateNephrologyStruvite stonesRACP Paediatrics

A 3-year-old with recurrent UTIs has a staghorn calculus on renal ultrasound. Urine culture repeatedly grows Proteus mirabilis. Urine pH is consistently >7.5. What is the most likely stone composition?

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Correct answer: E — Struvite (infection stones)

Struvite (magnesium ammonium phosphate) stones are infection-related stones associated with urease-producing organisms (Proteus, Klebsiella, Pseudomonas). These organisms split urea to produce ammonia, alkalinising the urine (pH >7.5) and promoting struvite crystallisation. They can form large staghorn calculi. Treatment requires both stone removal and eradication of the underlying infection.

Reference: RCH Melbourne – 2023 – Renal Calculi CPG; RACP Paediatric Curriculum – Nephrology