by Erich Rosenberger M.D.

Created on: December 10, 2007

Polycystic kidney disease (PKD) is the most common inherited genetic disorder in America. It is estimated that up to 500,000 people have polycystic kidney disease, with about 1 in 800 live births having the genetic defect. Despite being so common, it is relatively unknown. PKD is an autosomal dominant genetic disease. This means that it affects both men and women equally and that children of parents with PKD have a 50% chance of having polycystic kidney disease themselves.

The disease causes a series of fluid filled cysts to grow on the kidneys. If they get too big or numerous, these cysts can cause pain, blood in the urine, and in extreme cases, kidney failure.

At least two different genes have been identified as responsible for PKD. ADPKD1 is the most commonly affected gene. The other gene is called, not surprisingly, ADPKD2. Very creative, eh? Interestingly, the two defects are found on different chromosomes (16 and 4, respectively).

Polycystic kidney disease has what is known as 'variable penetrance'. This is a fancy way of saying that the severity of the disorder varies from person to person. Some people will go their entire lives with such a mild case of it that they never know they have it at all. In more severe cases, a person will end up in with kidney failure and require artificial kidney filtration known as dialysis. It is estimated that 10% of patients needed dialysis have PKD.

The most common symptom of polycystic kidney disease is hypertension (high blood pressure). Your kidneys are a key organ involved in the regulation of your blood pressure. When the cysts do enough damage, the ability to regulate your blood pressure will be reduced. Up to 60% of patients with PKD will develop hypertension.

Other symptoms of PKD include flank pain, especially over the kidney area - no surprise there. It is also common to see blood in your urine. Even if the blood is not visible, there can be microscopic blood, which can only be detected by your doctor with a microscope. Easily visible blood is commonly due to one of the cysts rupturing and leaking blood in to the kidney.

It is also possible for one of the cysts to become infected. In these cases, the person will usually have a fever and other signs of infection, in addition to flank pain and blood in the urine. These infections can be difficult to treat, and if they aren't managed properly, can lead to permanent kidney damage.

Polycystic kidney disease is associated with an increased incidence of cerebral aneurysms. This is a weakening in the arteries in the brain, causing the artery to bulge and potentially break open. The reason for this association with PKD is unknown.

There is no cure for polycystic kidney disease. Treatment involves dealing with the problems caused by the disorder as they present themselves. If you have further questions about this disease, talk to your doctor.

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