Cystinuria: current concepts and future directions.

Cystinuria, an autosomic recessive genetic disorder is an uncommon cause of nephrolithiasis characterized by an impairment of transport of cystine, ornithine, lysine, and arginine (COLA). Of these, only cystine is insoluble enough to cause stone formation. Although a classification exists that categorizes the disease depending on chromosomal mutation, this does not currently alter management which consists of increased fluid intake, urine alkalinization, reduced sodium intake and, if warranted, cystine-binding thiol drugs. Cystine stones are relatively resistant to fragmentation. Intrinsic characteristics on imaging may help in planning surgical treatment. Finally, advances in crystal growth inhibition are encouraging as they may provide a new tool to treat this condition which although uncommon, is treatable and has been associated with lower quality of life and renal function compared to other stone formers.