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Cystinuria

Stones - cystine; Cystine stones

 

Cystinuria is a rare condition in which stones made from an amino acid called cysteine form in the kidney, ureter, and bladder. Cystine is formed when two molecules of an amino acid called cysteine are bound together. The condition is passed down through families.

Causes

 

To have the symptoms of cystinuria, you must inherit the faulty gene from both parents. Your children will also inherit a copy of the faulty gene from you.

Cystinuria is caused by too much cystine in the urine. Normally, most cystine dissolves and returns to the bloodstream after entering the kidneys. 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. These crystals 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

 

Symptoms include:

  • Blood in the urine
  • Flank pain or pain in the side or back. Pain is most often on one side; it is rarely felt on both sides. Pain is often severe. It may get worse over days. You may also feel pain in the pelvis, groin, genitals, or between the upper abdomen and back.

 

Exams and Tests

 

The disorder is most often diagnosed after an episode of kidney stones. Testing the stones shows that they are made of cystine.

Unlike calcium-containing stones, cystine stones do not show up well on plain x-rays.

Tests that may be done to detect these stones and diagnose the condition include:

  • 24-hour urine collection
  • Abdominal CT scan , MRI, or ultrasound
  • Intravenous pyelogram (IVP)
  • Urinalysis

 

Treatment

 

The goal of treatment is to relieve symptoms and prevent more stones from forming. A person with severe symptoms may need to go into the hospital.

Treatment involves drinking plenty of fluids, especially water, to produce large amounts of urine. You should drink at least 6 to 8 glasses per day.

In some cases, fluids may need to be given through a vein (by IV).

Medicines may be prescribed to help dissolve the cystine crystals. Eating less salt can also decrease cystine release and stone formation.

You may need pain relievers to control pain in the kidney or bladder area when you pass stones. Smaller stones most often pass through the urine on their own. Larger stones may need extra treatments. Some large stones may need to be removed with surgery:

  • Extracorporeal shock wave lithotripsy (ESWL): Sound waves are passed through the body and are focused on the stones to break them into small, passable fragments. ESWL may not work well for cystine stones because they are very hard as compared with other types of stones.
  • Percutaneous nephrostolithotomy or nephrolithotomy : A small tube is placed through the flank directly into the kidney. A telescope is then passed through the tube to fragment the stone under direct vision.
  • Ureteroscopy for stones in the lower urinary tract.

 

Outlook (Prognosis)

 

Cystinuria is a chronic , lifelong condition. Stones commonly return. However, the condition rarely results in kidney failure. It does not affect other organs.

 

Possible Complications

 

Complications may include:

  • Bladder injury from stone
  • Kidney injury from stone
  • Kidney infection
  • Ureteral obstruction
  • Urinary tract infection

 

When to Contact a Medical Professional

 

Call your health care provider if you have symptoms of urinary tract stones.

 

Prevention

 

There are medicines that can be taken so cystine does not form a stone. Ask your provider about these medicines and their side effects. 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. Decreasing your intake of salt or sodium will help as well.

 

 

Open References

References

Elder JS. Urinary lithiasis. In: Kliegman RM, Stanton BF, St Geme JW, et al, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2016:chap 547.

Sakhaee K, Moe OW. Urolithiasis. In: Skorecki K, Chertow GM, Marsden PA, Taal MW, Yu ASL, eds. Brenner and Rector's The Kidney . 10th ed. Philadelphia, PA: Elsevier; 2016:chap 40.

 
  • Female urinary tract

    Female urinary tract - illustration

    The female and male urinary tracts are relatively the same except for the length of the urethra.

    Female urinary tract

    illustration

  • Male urinary tract

    Male urinary tract - illustration

    The male and female urinary tracts are relatively the same except for the length of the urethra.

    Male urinary tract

    illustration

  • Cystinuria

    Cystinuria - illustration

    Cystinuria is a disorder characterized by cystine stones in the kidney, ureter, and bladder. A genetic abnormality results in abnormal transport of amino acids in the kidney. The high levels of the amino acid cystine in the urine lead to stone formation. While this disease only accounts for 1-2 % of urinary tract stones in the general population, it is the most common cause among children.

    Cystinuria

    illustration

  • Nephrolithiasis

    Nephrolithiasis - illustration

    Kidney stones result when urine becomes too concentrated and substances in the urine crystalize to form stones. Symptoms arise when the stones begin to move down the ureter causing intense pain. Kidney stones may form in the pelvis or calyces of the kidney or in the ureter.

    Nephrolithiasis

    illustration

    • Female urinary tract

      Female urinary tract - illustration

      The female and male urinary tracts are relatively the same except for the length of the urethra.

      Female urinary tract

      illustration

    • Male urinary tract

      Male urinary tract - illustration

      The male and female urinary tracts are relatively the same except for the length of the urethra.

      Male urinary tract

      illustration

    • Cystinuria

      Cystinuria - illustration

      Cystinuria is a disorder characterized by cystine stones in the kidney, ureter, and bladder. A genetic abnormality results in abnormal transport of amino acids in the kidney. The high levels of the amino acid cystine in the urine lead to stone formation. While this disease only accounts for 1-2 % of urinary tract stones in the general population, it is the most common cause among children.

      Cystinuria

      illustration

    • Nephrolithiasis

      Nephrolithiasis - illustration

      Kidney stones result when urine becomes too concentrated and substances in the urine crystalize to form stones. Symptoms arise when the stones begin to move down the ureter causing intense pain. Kidney stones may form in the pelvis or calyces of the kidney or in the ureter.

      Nephrolithiasis

      illustration

     

    Review Date: 3/28/2016

    Reviewed By: Scott Miller, MD, urologist in private practice in Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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