What causes cystinuria?

Cystinuria is caused by changes (mutations) in the SLC3A1 and SLC7A9 genes. These genes encode a protein complex that helps control the reabsorption of amino acids (such as cystine) in the kidneys. Mutations in these genes disrupt the function of the protein complex, causing cystine to become more concentrated in the urine. As the concentration of cystine increases, cystine crystals and/or stones begin to form in the urinary tract leading to the many signs and symptoms associated with cystinuria.

Last updated on 05-01-20

How is cystinuria diagnosed?

Screening for cystinuria should be considered in people with recurrent or bilateral (i.e. affecting both kidneys) stones; those who develop stones at an early age (before age 30); and people who have a family history of cystinuria. A diagnosis is typically made after an episode of kidney stones when testing reveals that the stones are made of cystine.

The following tests may be recommended to detect kidney stones and diagnose cystinuria:

Last updated on 05-01-20

Is cystinuria inherited?

Cystinuria is inherited in an autosomal recessive manner. This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. The parents of an affected person usually each carry one mutated copy of the gene and are referred to as carriers. Carriers typically do not show signs or symptoms of the condition. When two carriers of an autosomal recessive condition have children, each child has a 25% (1 in 4) risk to have the condition, a 50% (1 in 2) risk to be a carrier like each of the parents, and a 25% chance to not have the condition and not be a carrier.

Last updated on 05-01-20

What is the long-term outlook for people with cystinuria?

Cystinuria is a chronic condition and many affected people experience recurrent cystine stones in the urinary tract (kidneys, bladder and ureters). In rare cases, frequent kidney stones can lead to tissue damage or even kidney failure.

Last updated on 05-01-20

How might cystinuria be treated?

Treatment of cystinuria is focused on relieving symptoms and preventing the formation of additional stones. A more conservative approach is typically tried first. This may include increasing fluid intake, regular monitoring of urinary pH, dietary restrictions (i.e. eating less salt) and increasing the pH of urine with potassium citrate supplements. If these strategies do not prevent the formation of stones, medications may be added to help dissolve the cystine crystals.

Treatment for cystinuria-related stones varies depending on the size and location of the stone, but may include:

Medscape Reference's Web site offers more specific information regarding the treatment and management of cystinuria. Please click on the link to access this resource.

Last updated on 05-01-20

Name: National Kidney Foundation 30 East 33rd Street
New York, NY, 10016, United States
Phone: 212-889-2210 Toll Free: 800-622-9010 Fax : 212-689-9261 Email: Url:
Name: American Kidney Fund, Inc. 6110 Executive Boulevard Suite 1010
Rockville, MD, 20852, United States
Phone: 301-881-3052 Toll Free: 866-300-2900 Email: Url:
Name: International Cystinuria Foundation 302 Belview Court
Longmont, CO, 80501-4779,

Note, these links are external searches against the National Laboratory of Medicine's drug database. You may need to adjust the search if there are no results found.

Drug Name Generic Name
Thiola Tiopronin

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