Polycystic Kidney Disease

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Overview, Causes, & Risk Factors

Polycystic kidney disease (PKD) is an inherited disorder (with autosomal dominant inheritance -- if one parent carries the gene, the children have a 50% chance of developing the disorder) where multiple clusters of cysts form on the kidneys. The exact mechanism that triggers cyst formation is unknown.

Cysts in the kidneys are associated with aneurysms of the blood vessels in the brain. They may be associated with diverticula of the colon, and with cysts in the liver, pancreas, and testes. As many as 50% of people with polycystic kidney disease also have cysts on the liver.

In early stages of the disease, the cysts enlarge the kidney and interfere with kidney function, resulting in chronic high blood pressure and kidney infections. The cysts may cause the kidneys to increase production of erythropoietin (the hormone that stimulates production of red blood cells) resulting in increased number of red blood cells, rather than the expected anemia. Bleeding into a cyst can cause flank pain. Kidney stones are more common than in people without the disorder. Hypertension caused by polycystic kidneys may be difficult to control.

The disease is slowly progressive, eventually resulting in end-stage kidney failure. It is also associated with liver disease, including infection of liver cysts. An autosomal recessive form of polycystic kidney disease also exists and appears in infancy or childhood; it tends to be very serious and progresses rapidly, resulting in end-stage kidney failure and generally causing death in infancy or childhood.

Autosomal dominant PKD occurs in both children and adults, but it is much more common in adults, often not presenting symptoms until middle age. It affects nearly 1 in 1,000 Americans. The actual number may be more, as some people do not have symptoms. The disorder may not be discovered unless procedures showing the disease are performed for other reasons.

Risks include a personal or family history of polycystic kidney disease.