Patients with CYSTINURIA excrete abnormally high amounts of cystine into the urine.   Cystine has poor solubility in urine and easily precipitates to form stones.  This genetically caused disease leads to recurrent stones which can occur at a young age. 

Cystine is an amino acid which is used for making proteins.  It contains sulfur which is the basis for preventive treatment.  Drugs containing sulfur, penicillamine and captopril, are used.  These sulfur containing drugs will bind to the sulfur component of the cystine.  As in other types of stones, raising urine volume is key to prevention of new stones or slowing growth of already existing stones.

A surgeon with experience in the care of cystinuria patients is necessary for successful surgical removal.  These stones are very hard and usually cannot be removed with lithotripsy.  People with cystinuria can go on to develop chronic kidney infections and permanent kidney scarring. Like struvite or infectious stones, cystine stones can develop into large staghorn shaped stones which fill the cavities of the kidney. Although they are not made of calcium, they can be seen on xray, unlike pure uric acid stones which cannot be seen on xray.  Stones can develop in children.  Diagnosis is made by collecting urine for 24 hours and measuring elevated urine cystine levels.  Distinctive hexagonal crystals are classically seen on microscopic urine analysis.