II. Epidemiology
- Represents 1% of Kidney Stones
III. Definitions
-
Cysteine
- Sulfar-containing Amino Acid
-
Cystine
- Two Cysteine molecules joined together
IV. Pathophysiology
- Inborn error of metabolism
- Disorder of dibasic Amino Acid transport
- Results in decreased Renal Cysteine resorption
-
Autosomal Recessive inheritance
- Only Homozygote patients form Cysteine Stones
-
Cysteine dissolves poorly at normal Urine pH
- Calculi form at Cysteine concentration >250 mg/day
- Forms staghorn calculi (as do Struvite Stones)
VI. Complications
VII. Management
-
General
- Diuresis: reduce Cysteine <300 mg/L
- Alkalinize urine (especially if Urine pH is low, acidic)
- Maintain Urine pH >5.5 (6.5 - 7.0 preferred)
- Potassium Citrate 10-20 mEq orally three times daily with meals
- Calcium Citrate 500 mg, two tablets daily with meals
- Protocol
- Tiopronin (Thiola) and
- Increase fluid intake to maximize Urine Output
- Other management
- Penecillamine
- Chemolysis (Tham-E, Acetylcysteine)
- Extracorporeal Shock Wave Lithotripsy (ESWL)
VIII. References
- Mobley (Feb 1999) Hospital Medicine, p. 21-38
- Goldfarb (1999) Am Fam Physician 60(8): 2269-76 [PubMed]
- Houshiar (1996) Postgrad Med 100(4): 131-8 [PubMed]
- Frassetto (2011) Am Fam Physician 84(11): 1234-42 [PubMed]
- Pietrow (2006) Am fam Physician 74(1): 86-94 [PubMed]
- Preminger (2007) J Urol 178(6): 2418-34 [PubMed]
- Portis (2001) Am Fam Physician 63(7):1329-38 [PubMed]
- Segura (1997) J Urol 158:1915-21 [PubMed]
- Teichman (2004) N Engl J Med 350:684-93 [PubMed]
- Trivedi (1996) Postgrad Med, 100(6): 63-78 [PubMed]