Polycystic kidney disease (PKD) is a genetic condition in which multiple fluid-filled sacs or cysts develop throughout the kidneys. These cysts vary in size and number, and may affect the ability of the kidneys to function. PKD cysts may eventually cause kidney damage if they become very large and numerous.
PKD is the fourth leading cause of kidney failure in North America. It is estimated that approximately 5% of patients with end-stage renal disease (ESRD) have PKD.
Depending on the type of PKD, symptoms usually begin either in early adulthood, between the ages of 30 and 40 years, or in infancy or early childhood. PKD can be detected by ultrasound. Both men and women of all races seem to be affected equally.
PKD is an inherited disease. This means that it is passed on from parents to children through genes. There are two types of PKD.
90% of people with PKD have autosomal dominant polycystic kidney disease (ADPKD), or adult PKD. The remaining 10% have autosomal recessive polycystic kidney disease (ARPKD), which affects infants and children.
ADPKD, or adult PKD, occurs when one parent has passed the gene on to a child. Because the gene is dominant, there is a 50% chance that a child will get PKD if one parent has the disease. In some cases, however, this form of PKD can occur spontaneously as a result of a new genetic mutation and is not passed on from parents.
ARPKD is the rarer form of PKD. ARPKD happens when each parent is a "silent carrier." This means that the parents carry the gene but are not affected by PKD. There is a 25% chance that a child born to parents that are both carriers will get the disease. If only one parent carries the gene, children will not be affected.
The kidneys, which are each about the size of a fist, play three major roles:
In early PKD, there are usually no symptoms. The symptoms are directly related to infections, swelling of the cysts, or the body's inability to remove harmful toxins that are circulating in the bloodstream.
The most common symptoms of PKD include back or side pain (between the ribs and hips), tenderness around the abdomen, or a feeling of fullness.
Someone with PKD might experience:
Urinary tract infections (UTI) and kidney stones are common among people with PKD. About 20% to 30% of people with PKD develop kidney stones. High blood pressure occurs in about 60% to 70% of people with PKD and for many is the first sign of the disease.
People with PKD have a 5% to 10% risk of developing an intracranial (brain) aneurysm (bulging in the wall of a blood vessel). Some aneurysms can leak or rupture, causing symptoms such as sudden severe headache, nausea and vomiting, and pain when moving the neck. These symptoms require immediate medical attention.
Cysts may also appear in other parts of the body such as the liver, pancreas, colon, testes, and brain. About one-quarter of people with PKD also develop weakened heart valves, which can sometimes lead to the need for valve replacement surgery.