What causes struvite stones in nephrolithiasis?

Updated: Jun 21, 2018
  • Author: Chirag N Dave, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Answer

Struvite stones account for 15% of renal calculi. They are associated with chronic urinary tract infection (UTI) with gram-negative, urease-positive organisms that split urea into ammonia, which then combines with phosphate and magnesium to crystalize into a calculus. Usual organisms include Proteus, Pseudomonas, and Klebsiella species. Escherichia coli is not capable of splitting urea and, therefore, is not associated with struvite stones. Because ammonia, a base, is produced during the catalytic process, the urine pH is typically greater than 7.

Underlying anatomical abnormalities that predispose patients to recurrent kidney infections should be sought and corrected. UTI does not resolve until stone is removed entirely.


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