What is Cystinuria?

Cystinuria is a genetic disorder that causes stones to form in the ureter, bladder and kidneys. These stones are made of cystine, which in most people breaks down easily. Those who suffer from cystinuria have a difficult time breaking down this amino acid and it can accumulate in various areas of the urinary tract, creating painful stones that are sometimes too large to pass from the body or that cause great pain when passing or blockage of the urinary tract.

People with this disease typically get it from parents who don’t have it. This is called an autosomal recessive pattern of inheritance; kids must inherit a copy of the defective gene from each parent. One defective gene doesn’t cause the disease.

Typically each parent has a single non-expressed gene for cystinuria that is passed to children. To make matters confusing, there are two separate genes that may cause this condition, and both parents would need to be carriers for the same gene in order to possibly pass this disease onto children. When two parents are carriers of the same gene, they would have a 25% chance of passing cystinuria onto each child.

When cystinuria occurs can vary depending on the patient. Some patients will have their first cystine stones in the first ten years of life. Others won’t show expression of the disease until they are older, but usually the illness will express in young adulthood. Degree of expression may vary too. Some people’s bodies seem to create stones on an almost constant basis and other people will only suffer from this condition occasionally. Size of stones is another variant, with some individuals producing fairly easy to pass stones and others producing very large cystine stones that might necessitate surgical removal.

The symptoms of this disease may vary too. When stones are present, people may feel pain in the flank (the back directly under the rib cage), or in the stomach and pelvis. Pain is typically strong and if a large stone is exiting the urinary tract, discomfort increases dramatically. Some people have a small amount of blood in urine too.

Such symptoms usually bring people to their doctors, who can diagnose the disease by looking at cystine levels in blood and urine. Clearly passage of a cystine stone indicates need to look for cystinuria, since cystine stones are not a common type of urinary tract stone. Doctors may then need to look for more stones with scans like magnetic resonance imaging (MRI), ultrasound or computerized axial tomography (CAT). Another test that may be done is an intravenous pyelogram (IVP), which is a special series of x-rays that examines the urinary tract.

Treatment for this condition often depends on patient response. Of utmost importance is increasing fluid intake, so that cystine doesn’t have time to collect in the urinary tract. In some patients, adequate fluid intake as per doctor recommendation effectively treats the disease. If needed, stones can be removed via surgical means, and people may also need pain medication when small stones are present and in the process of being passed.

These treatments don’t cure cystinuria, and unfortunately the disease has a high rate of recurrence and new stone formation. This means people may suffer from a greater share of pain much of the time, if they have frequent recurrences. Despite their being no cure, people with this condition do need to be under the care of a doctor at all times. There are potential complications that can arise when cystine stones form, and these include damage to the urinary tract, infection, and obstruction.