Definition

Polycystic kidney disease (PKD) is an inherited disease that causes cysts to form in the kidneys.

Description

These renal (of the kidney) cysts are filled with fluid and formed by individual nephrons, the subunits of the kidney. People with PKD may also have cysts in the liver, pancreas and other organs. About 10 to 15 percent may have swellings in the walls of blood vessels in the brain (called aneurysms). In time, virtually all of the nephrons of both kidneys either become cystic or are compressed, distorted and rendered increasingly ineffective by the pressure of adjacent cysts. In the process, both kidneys enlarge to three or four times the normal size, while function decreases.

The patient is unaware of the disease unless some complication; hypertension, blood in the urine, pain caused by bleeding into the kidney, a stone or infection, calls attention to the kidney, usually long before kidney failure has developed. Eventually, the kidneys become so large that it is possible to feel them.

There are two types of PKD. In the more common type (autosomal dominant PKD) almost half of the affected patients develop chronic kidney failure by the age of 60. A much more unusual type (autosomal recessive PKD) causes kidney failure in early childhood.

Causes and Risk Factors

This disease appears to occur all over the world among all socioeconomic and ethnic groups. Men and women are affected equally, and about 500,000 Americans have PKD.

Autosomal dominant PKD is the most common inherited disease in the United States. People get the disease from a parent who has PKD. If one parent has autosomal dominant PKD, each child has a 50/50 chance of inheriting the disease. In autosomal recessive PKD, parents may have no symptoms but still carry a recessive gene for the disease. If both parents have this recessive gene, one-fourth of the children can inherit the disease.

Symptoms

PKD usually affects both kidneys. The symptoms include abdominal or flank pain, blood in the urine (caused by blood vessels breaking in the cysts), kidney stones, and recurring bladder or kidney infections. High blood pressure is very common, occurring in about 50 percent of all people who have the disease. However, not everyone who has one of more of these symptoms has PKD. A high proportion of PKD patients develop kidney failure, which may require dialysis treatments or a kidney transplant.

Diagnosis

In addition to a medical history and physical exam, your physician may order blood tests and a urinalysis (urine test). Ultrasonography, which uses sound waves, is sensitive enough to detect most cases of PKD. Computed tomography (CT scan), especially when combined with dye infusion, is one of the most sensitive tests available.

Treatment

At present, there is no specific treatment for PKD. However, it is important for anyone with PKD to have regular checkups.

Treatment is confined to complications such as infection, stones, bleeding and hypertension.

A low-protein diet may slow progression of the disease.

Operations, such as cyst puncture or removal, designed to relieve pressure, may make the condition worse.

Blood pressure control and prevention of kidney stones and infections have improved the prognosis for those with PKD. Dialysis and transplantation are other alternatives.

Questions to Ask Your Doctor

• What tests will be done?
• Are there risks or side effects associated with these tests?
• How serious is this condition?
• Has this condition affected any other vital organs?
• What type of treatment will you be recommending?
• How effective is this treatment?
• Are there any alternative treatments?
• Will you be prescribing any medication? What are the side effects?