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struvite (magnesium ammonium phosphate) stone
Etiology:
- all patients with struvite stones are infected with urease-producing bacteria:
1) Proteus
2) Staphylococcus
3) Klebsiella
4) Pseudomonas
5) E coli
Epidemiology:
- more common in women than men
- most frequent in elderly women with chronic urinary tract infections
Clinical manifestations:
- struvite stones may be staghorn & bilateral (50%)
Laboratory:
1) pH of the urine is alkaline, occasionally > 7.8
2) stones contain bacteria
Management:
1) antibiotic treatment urinary tract infection caused by urease-producing bacteria helps prevent struvite stone
2) once struvite stones are formed, surgery provides definitive treatment
a) presurgical antibiotics
b) percutaneous stone extraction (+/- extracorporeal shock-wave lithotripsy)
3) bactericidal antibiotics for 6-12 months
4) acetohydroxamic acid (urease inhibitor) rarely used due to toxicity [1]
Related
struvite (magnesium ammonium phosphate, MgNH4PO4)
urease
Specific
staghorn calculus
General
urinary calculus (stone, nephrolithiasis, urolithiasis)
References
- Medical Knowledge Self Assessment Program (MKSAP) 11, 16, 17, 18, 19.
American College of Physicians, Philadelphia 1998, 2012, 2015, 2018, 2021
- Marien T, Miller NL.
Treatment of the Infected Stone.
Urol Clin North Am. 2015 Nov;42(4):459-72. Review.
PMID: 26475943