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Cystic Kidney Disease

Inherited and Congenital Kidney cystic Diseases

Some kidney diseases result from hereditary factors.  Polycystic kidney disease (PKD), for example, is a genetic disorder in which many cysts grow in the kidneys. PKD cysts can slowly replace much of the mass of the kid­neys, reducing kidney function and leading to kidney failure. Some kidney problems may show up when a child is still developing in the womb.  Exam­ples include autosomal recessive PKD, a rare form of PKD, and other developmental problems that interfere with the normal formation of the nephrons.

polycystic-kidney-diagram

Acquired cystic kidney disease (ACKD)

Many people with chronic kidney disease develop ACKD, a condition in which the kidneys develop fluid-filled sacs called renal (kidney) cysts. ACKD occurs in children and adults. The cysts are more likely to develop in people who are on hemodialysis or peritoneal dialysis. Kidney failure, not dialysis, causes the cysts. However, the risk of developing ACKD increases with the number of years a person is on dialysis.

About 20 percent of people starting dialysis treatments already have ACKD.
About 60 to 80 percent of people on dialysis for 4 years develop ACKD.
About 90 percent of people on dialysis for 8 years develop ACKD.

In ACKD, the kidneys develop fluid-filled sacs called cysts.

In most cases, the cysts are harmless and require no treatment. Sometimes problems occur-including infection in the cyst, which may be associated with fever and back pain. Sometimes the cysts bleed and blood will appear in the urine. Blood in the urine should always be reported to a doctor.

Although doctors debate the exact percentage, somewhere between 10 and 20 percent of people with ACKD develop kidney tumors, which in some cases are cancerous. The rate of kidney cancer in people with ACKD is low, but it is higher than the rate in the general population.

What are the symptoms of ACKD?

ACKD often has no symptoms. If a cyst becomes infected, a person may have back pain, fever, or even chills. If a cyst bleeds, a person will often notice blood in the urine.

How does ACKD differ from polycystic kidney disease (PKD)?

ACKD differs from PKD in several ways. People with PKD often have a family history of PKD. They are born with the disease-causing gene. No disease-causing gene is associated with ACKD. PKD is associated with enlarged kidneys and cyst formation in other parts of the body. In ACKD, the kidneys are normal sized or smaller and cysts do not occur in other parts of the body. In PKD, the presence of cysts marks the onset of disease. People with ACKD already have chronic kidney disease when they develop cysts.

How kidney cystic disease is diagnosed?

A doctor may suspect kidney cystic disease based on a patient’s history and symptoms. To confirm the diagnosis, the doctor may order one or more imaging procedures:

  • Ultrasound. In an ultrasound, or sonogram, a technician glides a device, called a transducer, over the abdomen. The transducer sends harmless sound waves into the body and catches them as they bounce off the internal organs to create a picture on a monitor. Abdominal ultrasounds are used to evaluate the size and shape of the kidneys.
  • Computerized tomography (CT) scans. CT scans use a combination of x-rays and computer technology to create three-dimensional images. Sometimes a contrast dye is injected into the patient to better see the structure of the kidneys. CT scans require the patient to lie on a table that slides through a donut-shaped scanning machine. CT scans can help identify cysts and tumors in the kidneys.
  • Magnetic resonance imaging (MRI). MRI machines use radio waves and magnets to produce detailed pictures of internal organs and tissues. No exposure to radiation occurs. With most MRI machines, the patient lies on a table that slides into a tunnel that may be open-ended or closed at one end. Some newer machines are designed to allow the patient to lie in a more open space. Like CT scans, MRIs can help identify cysts and tumors.

polycystic-kidney
Images of the Kidneys may help the health care provider distinguish ACKD from PKD.

How is kidney cystic disease treated?

If ACKD is not causing pain or discomfort, no treatment is required. Infections are treated with a course of antibiotics. If large cysts are causing pain, they may be drained using a long needle inserted through the skin.

Kidney doctors usually follow cysts regularly with imaging testing. If tumors are suspected, a person may need regular examinations to monitor the kidneys for cancer. Some doctors recommend all patients be screened for kidney cancer after 3 years of dialysis. In rare cases, surgery is used to stop cysts from bleeding and to remove tumors or suspected tumors.

For patients with PKD, newer medications that will decrease the cyst growth are being investigated. Measures that are thought to decrease cyst growth are to increase daily water intake, diet with low animal protein content and rich on fruits and vegetables.