Cystinuria: current diagnosis and management.

Cystinuria is an inherited disorder of the dibasic amino acid transport system in the proximal tubule and the small intestine. Two responsible genes have been identified, the SLC3A1 on chromosome 2 and the SLC7A9 on chromosome 19. The inability of renal tubules to reabsorb cystine and the relative insolubility of cystine at physiological urine pH lead to stone formation. Cornerstone of the treatment remains stone prevention with hyperhydration, urinary alkalization, and pharmacologic therapy. Repeated stone formation necessitates urologic interventions, which mainly include minimally invasive procedures. The appropriate management of cystinuria is often challenging and requires close follow-up of the patient.