In this Article
- Cystinuria facts
- What is cystinuria?
- How frequent is cystinuria?
- What is a transport defect?
- What causes cystinuria?
- What happens with cystine in the urine?
- What problem do the cystine stones cause?
- What happens with a urinary obstruction?
- What is the effect of urinary obstruction on the kidney?
- What are the signs and symptoms of cystinuria?
- What use is early diagnosis?
- How is cystinuria treated?
- What are the laboratory findings in cystinuria?
- How is cystinuria inherited?
- How long has cystinuria been known?
What is the effect of urinary obstruction on the kidney?
The pressure on the kidneys and the urinary infections result in damage to the kidneys. The damage can progress to renal insufficiency and end-stage kidney disease which require renal dialysis or a kidney transplant.
What are the signs and symptoms of cystinuria?
The stones that form in cystinuria are directly or indirectly responsible for all of the signs and symptoms of the disease, including:
- Hematuria - blood in the urine;
- Flank pain - pain in the side, due to kidney pain;
- Renal colic - intense, cramping pain due to stones in the urinary tract;
- Obstructive uropathy - urinary tract disease due to obstruction; and
- Urinary tract infections.
What use is early diagnosis?
Because of the potential effectiveness of treatment, early diagnosis of cystinuria is important in all persons, regardless of age, who form urinary stones. Failure to diagnose cystinuria early and treat it consistently with the utmost vigor can result in morbidity (illness) and mortality (death). Survival may depend upon dialysis or a kidney transplant.
How is cystinuria treated?
High fluid intake: The foremost aim of treatment is to prevent the formation of cystine stones. This goal is attained mainly by increasing the volume of urine. The reason for the increased urine volume is simple. By increasing the volume of urine, the concentration of cystine in the urine is reduced which prevents cystine from precipitating from the urine and forming stones.
Cystine stones in many patients can be dissolved and new ones prevented by a high fluid intake. What high fluid intake means in this context is an absolute minimum of 4 liters (roughly 4 quarts) per day. An intake of 5 to 7 liters a day is ideal. The fluids must be spaced out, including through the night. It has been said that people with cystinuria must realize that "for them, water is a necessary drug."
Alkalizing the urine: Another strategy that has been attempted to treat cystinuria is alkalization of the urine. The rationale is that in an alkaline (nonacidic) liquid, cystine tends to stay in solution and there it does no harm. To make the urine alkaline, sodium bicarbonate (and similar substances) have been used. This treatment is not without hazard because it can, while preventing cystine stones, lead to the formation of other types of kidney stones.
Penicillamine: For people with cystinuria in whom a consistent, conscientious high fluid intake does not succeed in halting the formation of stones, another option available is regular treatment with a drug called penicillamine. Penicillamine (Cuprimine, Depen) acts to form a complex with cystine that is 50 times more soluble than cystine itself. The side effects of penicillamine are rarely severe enough to prevent its use.
Percutaneous nephrolithotripsy (PNL): The stones in cystinuria are too dense to be broken up by shock waves produced outside the body (extracorporeal shock wave lithotripsy) as can be done with some other types of common kidney stones. Instead, a technique designed for removing dense (and very large) stones is utilized: percutaneousnephrolithotripsy (PNL).
PNL is performed via a port created by puncturing the kidney through the skin and enlarging the access port to 1 cm (about 3/8 inch) in diameter. There is no surgical incision. PNL is done under real-time live x-ray control (fluoroscopy). Because x-rays are involved, a super-specialist in radiology (an interventional radiologist) may perform this part of the procedure. The endourologist (another subspecialist) then inserts instruments via this port into the kidney to break up the stone and remove most of the debris from the stone.
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