Polycystic kidney disease

Definition:

Polycystic kidney disease is an inherited kidney disorder that enlarges the kidneys and interferes with their function because of multiple cysts on the kidneys.

Alternative Names:

Cysts - kidneys; Kidney - polycystic; Autosomal dominant polycystic kidney disease; ADPKD

Causes, incidence, and 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.

PKD is associated with brain aneurysms, diverticula of the colon, and with cysts in the liver, pancreas, and testes . As many as half of people with PKD 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 too many red blood cells, rather than the expected anemia of chronic kidney disease.

Bleeding in a cyst can cause flank pain . Kidney stones are more common in people with PKD. Hypertension (high blood pressure) caused by polycystic kidneys may be difficult to control.

The disease gets worse slowly, 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, with symptoms often not showing up 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 tests revealing the disease are performed for other reasons.

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

This abdominal CT scan shows cysts in the liver and kidneys (polycystic disease). The liver is the large organ on the left side of the screen. The dark spots in the liver are cysts.

Kidney and liver cysts - CT scan

This abdominal CT scan shows multiple cysts in the liver and spleen. Note the dark circular cyst in the liver (left side of screen) and the large, irregular, circular cyst in the spleen (bottom, right side of screen).

Liver and spleen cysts - CT scan

Symptoms:

• Blood in the urine
• Flank pain on one or both sides
• Excessive urination at night
• Abdominal pain or tenderness
  
  • any part of abdomen
  • right upper quadrant
  • left upper quadrant

Additional symptoms that may be associated with this disease include the following:

• Nail abnormalities
• Painful menstruation
• Joint pain
• Drowsiness
• High blood pressure

Signs and tests:

Examination may show high blood pressure, kidneys or abdominal masses (aggregations of cells) which are felt by touch during examination, abdominal tenderness over the liver (right upper quadrant), and enlarged liver . There may be heart murmurs or other signs of aortic insufficiency or mitral insufficiency .

• A urinalysis may show urine protein or blood in the urine .
• A CBC may show decreased or increased RBCs and hematocrit .
• Cerebral angiography may show associated aneurysms.

Polycystic kidney disease, and associated cysts on the liver or other organs, may be detected with the following tests:

• Abdominal ultrasound
• Abdominal CT scan
• Abdominal MRI scan
• IVP

In a family with several members with PKD, genetic linkage tests can be performed to determine with fair reliability whether a person at risk carries the PKD gene.

Treatment:

Currently, no treatment can prevent the cysts from forming or enlarging. Treatment goals are the reduction of symptoms and prevention of complications.
Hypertension may be difficult to control, but control of it is the most important aspect of treatment. Treatment may include antihypertensive and/or diuretic medications, low-salt diet, or other treatments.
Any urinary tract infection should be treated promptly with appropriate antibiotics.
Any symptoms of anemia may be treated with iron and other supplements, erythropoietin administration, or blood transfusion.
Surgical or radiologic drainage of cysts may be indicated because of pain, bleeding, infection, or obstruction. (There are usually too many cysts to make removal a feasible alternative.)
Surgical removal of one or both kidneys may be required. Treatment of end-stage kidney disease may include kidney dialysis or kidney transplantation.

Support Groups:

The stress of illness can often be helped by joining a support group where members share common experiences and problems. See kidney disease - support group .

Expectations (prognosis):

Polycystic kidney disease progresses slowly but persistently. Medical treatment may provide relief of symptoms for many years. Eventual end-stage kidney failure is common.
The absence of systemic disease or autoimmune disease makes people with polycystic kidney disease good candidates for kidney transplantation.

Complications:

• High blood pressure
• Anemia
• Recurrent urinary tract infection
• Recurrent kidney infection
• Kidney stones
• Kidney failure, mild to severe
• End-stage kidney disease
• Bleeding or rupture of cysts
• Infection of liver cysts
• Liver failure, mild to severe

Calling your health care provider:

Call your health care provider if symptoms indicate polycystic kidney disease may be present.
Call for an appointment with your health care provider if there is a family history of polycystic kidney disease or associated disorders and children are planned. Genetic counseling may be offered because of the pattern of inheritance of the disorder.