Which statement best describes struvite stones?

Which statement best describes struvite stones?

• A. Infection with urease-producing bacteria
• B. Hypercalcemia
• C. Dehydration with low urine pH
• D. Low urinary magnesium

Answer: (A)

Struvite stones form when urine becomes alkaline due to urease-producing bacteria that split urea into ammonia. The resulting high pH promotes precipitation of magnesium ammonium phosphate, the composition of struvite stones. This makes infection with urease-producing organisms the best description. Hypercalcemia is tied to calcium-containing stones, not struvite; dehydration with a low urine pH would favor other stone types, and low urinary magnesium is not the cause of struvite formation (though magnesium is a component, its level isn’t the driver). Clinically, these stones often accompany persistent urinary infections and can form large, branching staghorn calculi; management focuses on treating the infection and removing the stones, with prevention centered on preventing urease-producing infections.

Struvite stones form when urine becomes alkaline due to urease-producing bacteria that split urea into ammonia. The resulting high pH promotes precipitation of magnesium ammonium phosphate, the composition of struvite stones. This makes infection with urease-producing organisms the best description. Hypercalcemia is tied to calcium-containing stones, not struvite; dehydration with a low urine pH would favor other stone types, and low urinary magnesium is not the cause of struvite formation (though magnesium is a component, its level isn’t the driver). Clinically, these stones often accompany persistent urinary infections and can form large, branching staghorn calculi; management focuses on treating the infection and removing the stones, with prevention centered on preventing urease-producing infections.