What is Cystinuria ?

Cystinuria literally means 'cystine in the urine'. Cystine is an amino acid, which is a ‘building block’ of protein in the body. People who suffer from cystinuria have a problem with the transport of cystine in the kidney. This leads to a build up of cystine in the urine, which if the levels are high enough can form crystals - these then enlarge and become stones. Cystinuria was first described 200 years ago in 1810 (1) and the first known cystine stone is shown in the image. (reproduced with permission from Gordon Museum, Guy's, Kings and St. Thomas' Hospitals Medical Schools, KCL, London).

The exact incidence in unknown but it is thought that 1 in 2000 people in the UK are affected by cystinuria. For this reason the Rare Renal Diseases group have a registry to try and capture this data. It is more common in Caucasians but affects men and women equally although men may have a more severe form of the disease. Amongst people who form kidney stones, 1% of adults will have cystine stones and 6-8% of children.

Cystinuria is an inherited condition. Most people present with cystinuria in their 20's or 30's, although it can present at any age. Commonly people have had episodes of stone formation for a few years before the diagnosis is made. Cystinuria cannot be cured but it is possible to reduce the chance of getting stones (see What can I do ? and Diet - What should I eat ?). It is important that patients with cystinuria are seen regularly by a urologist or nephrologist with an interest in stone disease to ensure all adequate measures are being used to prevent stones and preserve kidney function. When stones form it is also important to get prompt treatment. If stones don't pass spontaneously then surgical treatment may be required. If the stones are left untreated for a long time kidney function may be permanently damaged and in extremely rare cases patients may need a kidney to be removed.

(1) Wollaston WH. On cystic oxide: a new species of urinary calculus. Trans R Soc (London) 1810; 100: 223.