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Cystinuria

Wake Forest Baptist Approach Chances are if a patient has one kidney stone, more will form in the future. That’s why at Wake Forest Baptist, we take a comprehensive approach to care – focusing not only on the removal of kidney stones, but on preventing their recurrence. In patients with recurrent stones, this often requires a careful evaluation to identify metabolic abnormalities that predispose patients to stone formation. “It has been demonstrated that medical therapy and dietary modifications can reduce stone activity,” said Dean Assimos, M.D., professor of urology. “A metabolic evaluation enables us to recommend a program that incorporates dietary modifications and possibly medications to reverse or attenuate stone activity.” Assimos treats hundreds of stone patients a year, including those with complex stone problems who have failed shock wave lithotripsy. He specializes in metabolic evaluations and all treatment options, including shock wave lithotripsy, ureteroscopic stone removal, laparoscopic surgery, percutaneous nephrolithotomy and open surgery. Assimos is vice-chair of an American Urological Association panel that writes guidelines for the treatment of kidney stones. He said metabolic evaluations are recommended for pediatric stone patients and for adult patients with recurrent stones, cystinuria, multiple remaining stones, evidence of stone growth over time, as well as for those with one kidney or with renal dysfunction. It is strongly considered for commercial airline pilots with stones as they must be free of stones to work. The evaluation may include a comprehensive patient history, imaging, stone analysis, urine studies, blood tests and genetic testing. Some of these components are done in every case and others are used selectively. Assimos said stone analysis is very important as it directs further testing. Ranked No. 1 in the nation in the number of research grants from the National Institutes of Health, the Department of Urology is also active in working to identify risk factors for stones, understand how they form and identify potential treatment targets. Patients have the potential to benefit from new knowledge and treatments that result from the program, which is headed by Assimos and Ross Holmes, Ph.D. For example, Holmes and Assimos were one of the first research groups to uncover the importance of dietary oxalate in stone formation and Holmes has quantified the amount of oxalate in several foods using a technique that he developed.       Cystinuria Female urinary tract Male urinary tract Cystinuria Nephrolithiasis   Definition: Cystinuria is a condition passed down through families in which stones form in the kidney, ureter, and bladder. See also: Nephrolithiasis Alternative Names: Stones - cystine; Cystine stones Causes, incidence, and risk factors: Cystinuria is an autosomal recessive disorder, so you must inherit the faulty gene from both parents in order to have symptoms. Cystinuria is caused by too much of an amino acid called cystine in the urine. After entering the kidneys, most cystine normally dissolves and goes back into the bloodstream. But people with cystinuria have a genetic defect that interferes with this process. As a result, cystine builds up in the urine and forms crystals or stones, which may get stuck in the kidneys, ureters, or bladder. About one in every 10,000 people have cystinuria. Cystine stones are most common in young adults under age 40. Less than 3% of urinary tract stones are cystine stones. Symptoms: Blood in the urine Flank pain or pain in the side or back Usually on one side; rarely felt on both sides Often severe May get increasingly worse over days Pain may also be felt in the pelvis, groin, genitals, or between the upper abdomen and the back. Signs and tests: The disorder is usually diagnosed after an episode of kidney stones. Analysis of the stones shows they are made of cystine. Tests that may be done to detect stones and diagnose this condition include: Abdominal CT scan, MRI, or ultrasound Intravenous pyelogram (IVP) Urinalysis (may show cystine crystals) 24-hour urine collection (shows high levels of cystine) Treatment: The goal of treatment is to relieve symptoms and prevent the development of more stones. A person with severe symptoms may need to be admitted to a hospital. Treatment involves drinking plenty of fluids, particularly water, so that large amounts of urine are produced. The patient should drink at least 6-8 glasses per day. In some cases, fluids may need to be given through a vein (by IV). Medications may be prescribed to help dissolve the cystine crystals. Eating less salt can also decrease cystine excretion and stone formation. Pain relievers may be needed to control pain in the kidney or bladder area associated with the passage of stones. The stones usually pass through the urine on their own. If they do not, surgery may be needed: Percutaneous nephrostolithotomy or nephrolithotomy Ureteroscopy, for stones in the lower urinary tract Extracorporeal shock wavelithotripsy (ESWL). This procedure is not as successful for removal of cystine stones as it is for other types of stones) Expectations (prognosis): Cystinuria is a chronic, lifelong condition. Stones commonly return. However, the condition rarely results in kidney failure, and it does not affect other organs. Complications: Bladder injury from stone Ureteral obstruction Kidney injury from stone Kidney infection Urinary tract infection Calling your health care provider: Call your health care provider if you have symptoms of urinary tract stones. Prevention: There is no known prevention for cystinuria. Any person with a known history of stones in the urinary tract should drink plenty of fluids to regularly produce a high amount of urine. This allows stones and crystals to leave the body before they become large enough to cause symptoms. References: Rogers A, Kalakish S, Desai RA, Assimos DG. Management of cystinuria. Urol Clin North Am. 2007;34(3).

Review Date:8/30/2009 Reviewed By:Louis S. Liou, MD, PhD, Assistant Professor of Urology, Department of Surgery, Boston University School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.