Polycystic kidney disease, or PKD, usually refers to a genetic or inherited disease that is sometimes called "adult PKD" because it normally appears in adult life. A less common type of PKD occurs primarily in babies and children.

In PKD, cysts, or fluid-filled pouches, are found primarily in the kidney but they can also affect other organs, including the liver, pancreas, spleen and ovaries. Outpouchings may occur in the walls of the large intestine and in the walls of blood vessels in the brain, where they may cause aneurysms. They may also be found in the abdominal wall, causing hernias. In addition, the valves of the heart may be involved, becoming floppy and resulting in a heart murmur in some patients.

How common is PKD?

PKD is the most common life-threatening genetic disease. Scientists estimate that it affects between one in 400 and one in 1,000 individuals. It is found in all races and occurs equally in men and women.

Who is at risk for developing PKD?

The adult type of PKD (also called autosomal-dominant PKD or ADPKD) is passed from parent to child by an autosomal-dominant type of inheritance. This means that only one copy of the abnormal gene is needed to cause the disease. Therefore, if one parent has the disease, each child has a 50-50 chance of getting the disease. The risk is the same for every child, regardless of how many children develop the disease.

The less common form of PKD (also called autosomal recessive PKD or ARPKD) is passed by an autosomal recessive pattern of inheritance. This means that both parents carry the abnormal gene, and both must pass the gene to the child in order for the child to get the disease. In this situation, every child has a 25 percent chance of getting the disease in a family that is at risk.

What are the clues that someone has PKD?

People who have inherited ADPKD often do not notice anything unusual until they are 30 to 40 years old. The first noticeable symptoms may include:

• high blood pressure
• back or side pain
• an increase in the size of the abdomen
• blood in the urine
• frequent bladder or kidney infections.

High blood pressure is the most important treatable risk factor in PKD. Occasionally, patients may develop headaches related to high blood pressure or their doctors may detect high blood pressure during a routine physical exam. Finally, about 25 percent of PKD patients have a so-called floppy valve in the heart, and some of these develop a fluttering or pounding in the chest as well as chest pain. These symptoms almost always disappear on their own but may be the first hint that someone has PKD.

How is PKD diagnosed?

Today, ultrasound is the most reliable, inexpensive and non-invasive way to diagnose PKD. If someone at risk for PKD is older than 30 years and has a normal ultrasound of the kidneys, he or she probably does not have PKD. Occasionally, a CT scan (computed tomography scan) may detect smaller cysts that cannot be found by an ultrasound.

At present, PKD cannot be diagnosed by a single blood test. However, in some situations where it is important to have a diagnosis (for example, if a family member wants to donate a kidney to an affected parent or sibling, and ultrasound and CT scans are normal), special blood tests on at least three family members can be done to get a diagnosis in the at-risk individual. This form of testing is called gene linkage analysis.

Does everyone with PKD develop kidney failure?

No. About 50 percent of patients with PKD will have kidney failure by age 60, and about 60 percent will have kidney failure by age 70. Certain people have an increased risk of kidney failure including:

• men
• patients with the most common form of PKD (ADPKD)
• patients with high blood pressure
• patients with protein or blood in their urine
• women with high blood pressure who have had more than three pregnancies.

How is PKD treated?

At present, there is no cure for PKD, although a lot of research is being done. Many studies suggest that some treatments may slow the rate of kidney disease in PKD, but further research is needed before these treatments can be used in patients. Other studies are improving our understanding of the genetic basis of PKD.

In the meantime, many supportive treatments can be done to help prevent or slow down loss of kidney function in PKD. These include:

• careful control of blood pressure
• prompt treatment of a bladder or kidney infection
• lots of fluid and bed rest when blood in the urine is first noted
• a healthy lifestyle with regard to smoking, exercise, weight control and salt intake.

Should people with PKD take a special diet?

At present, no specific diet is known to prevent cysts from developing in patients with PKD. Reducing salt intake helps control blood pressure in PKD patients who have high blood pressure. Low fat and moderate caloric intake are recommended to avoid becoming overweight.

Is exercise recommended for people with PKD?

Absolutely. However, exercises that are potentially harmful to the kidney, such as contact sports, should be avoided. It is important not to become too dehydrated during any physical activity.

Updated: 06/03/04

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See also in this A-Z guide:

• How Your Kidneys Work
• Warning Signs of Kidney and Urinary Tract Diseases

All health information in this A-Z Guide has been approved for medical accuracy by the Scientific Advisory Board of the National Kidney Foundation. This information was current as of the date listed at the top of the page. Our Scientific Advisory Board members.

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©2006 National Kidney Foundation. All rights reserved. This material does not constitute medical advice. It is intended for informational purposes only. No one associated with the National Kidney Foundation will answer medical questions via e-mail. Please consult a physician for specific treatment recommendations.