II. Epidemiology

  1. More common in women
  2. Represents 15-20% of Kidney stones

III. Pathophysiology

  1. Most common cause of staghorn calculi
    1. Cysteine Nephrolithiasis also forms staghorn stones
  2. Components
    1. Magnesium
    2. Ammonium
    3. Calcium Phosphate

IV. Risk Factors

  1. Neurogenic Bladder
  2. Urinary tract foreign body
  3. Urinary Tract Infection with urea-splitting Bacteria
    1. Infection alkalinizes urine (Urine pH>7)
    2. Increases ammonium concentration
    3. Bacterial causes
      1. Proteus mirabilis
      2. Ureaplasma urealyticum
      3. KlebsiellaPneumonia
      4. Pseudomonas

V. Imaging

  1. Struvite Stones are faintly radiopaque
  2. Pneumaturia (gas in urinary tract) may be seen with Proteus

VI. Complications

  1. Infection (common)

VII. Management

  1. Start antibiotics
    1. High risk of overwhelming Sepsis
  2. Urgent urology Consultation
    1. Surgery delayed until afebrile for 48 hours
  3. Consider acetohydroxamic acid (Lithostat)
    1. Irreversible urease inhibitor
      1. Prevents struvite crystallization
    2. Risk of Deep Vein Thrombosis
    3. Indications
      1. Calculus-related severe infections
      2. Patients who are not surgical candidates

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