Renal

Cysteine Calculi

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Cysteine Calculi, Cysteine Stone, Cysteine Nephrolithiasis, Cystine Calculi, Cystine Stone, Cystine Nephrolithiasis, Cystinuria

  • See Also
  • Epidemiology
  1. Represents 1% of Kidney stones
  • Definitions
  1. Cysteine
    1. Sulfar-containing amino acid
  2. Cystine
    1. Two Cysteine molecules joined together
  • Pathophysiology
  1. Inborn error of metabolism
    1. Disorder of dibasic amino acid transport
    2. Results in decreased Renal Cysteine resorption
  2. Autosomal Recessive inheritance
    1. Only Homozygote patients form Cysteine Stones
  3. Cysteine dissolves poorly at normal Urine pH
    1. Calculi form at cysteine concentration >250 mg/day
    2. Forms staghorn calculi (as do Struvite Stones)
  • Types
  1. Pure Cysteine Stones
  2. Mixed cysteine and calcium oxalate
  • Complications
  • Management
  1. General
    1. Diuresis: reduce cysteine <300 mg/L
    2. Alkalinize urine (especially if Urine pH is low, acidic)
      1. Maintain Urine pH >5.5 (6.5 - 7.0 preferred)
      2. Potassium Citrate 10-20 mEq orally three times daily with meals
      3. Calcium Citrate 500 mg, two tablets daily with meals
  2. Protocol
    1. Tiopronin (Thiola) and
    2. Increase fluid intake to maximize Urine Output
  3. Other management
    1. Penecillamine
    2. Chemolysis (Tham-E, Acetylcysteine)
    3. Extracorporeal Shock Wave Lithotripsy (ESWL)