By Alan S. Kliger, MD

Polycystic kidney disease (PKD) is a common cause of decreased kidney function, causing chronic kidney disease (CKD) in children and adults. It is found in all ethnic groups worldwide, affecting one in every 500 to 1,000 people. Other inherited kidney diseases include Alports Syndrome or Hereditary Nephritis, Thin Basement Membrane Disease, Tuberous Sclerosis, Fabry Disease and Medullary Cystic Kidney Disease. These occur far less frequently than PKD, which accounts for 5 percent of dialysis and kidney transplant patients in the U.S. and Europe.

When kidneys are affected by PKD, fluid-filled cysts, like small water balloons, form and grow in both kidneys. This causes the kidneys to enlarge, pushing and distorting the normal kidney structures. Enlarged kidneys often cause pain in the back or sides, and are sometimes complicated by bleeding into the cysts. Patients with PKD may experience chronic pain, which may become severe if cysts rupture. Episodes of bloody urine occur from time to time, and some people have kidney stones. Cyst fluid and urine can become infected, causing chills, fever and worsening back pain.

Not all people with PKD are affected the same way. Some affected individuals have well-preserved kidney function for many years, even into the ninth decade of life, while others show declining kidney function and require dialysis or transplantation early in life. Most PKD patients come to their doctor’s attention in their 20s or 30s, with kidney failure following in five to 10 years. As kidney disease progresses, high blood pressure is often present, occurring in more than 75 percent of PKD-affected people.

PKD may cause cysts to form in organs other than the kidney. Seventy-five percent of people with PKD have cysts in the liver. Such cysts do not cause liver failure, and rarely cause problems by enlarging the liver or with infections in these cysts. Other organs rarely affected by cyst formation include the pancreas, eyes and ovaries. PKD patients have a higher-than-normal incidence of diverticuli (small outpouchings) in the intestinal colon and heart valve abnormalities. Outpouching is the process of turning outward or inside out, in regards to a membrane. Growing liver and kidneys enlarge the bellies of many PKD sufferers, sometimes causing a feeling of bloating and, in some people, abdominal and inguinal hernias.

Approximately 4-8 percent of people with PKD have small aneurysms – blood vessel outpouchings caused by weakness in blood vessel walls – in the blood vessels in the brain (intracranial aneurysms), and rarely in the aorta (the large artery from the heart feeding other blood vessels). Brain aneurysms occur in small numbers (less than 5 percent) of PKD families. Since a ruptured brain aneurysm can be life threatening, tests to look for brain aneurysms have been advised for PKD patients with a family history of brain aneurysms. A three-dimensional magnetic resonance arteriogram (MRA) test can find such aneurysms. Small aneurysms are probably safe to watch and follow over time. Larger ones can be treated surgically, or with microsurgical clipping, or a radiologist placing small coils in the aneurysms through a catheter to clot them.

Most PKD families have an “autosomal dominant” inheritance pattern. In this type of inheritance, when a person with PKD marries an unaffected spouse, each child has a 50/50 chance of having PKD. A much less common “autosomal recessive” type of PKD has less likelihood of passing the disease to their children. This type of PKD is usually first discovered in infancy or childhood, and may be accompanied by scarring of the liver and abnormal bile ducts. Abnormalities of different genes have been found for each of these types of PKD.

What does the doctor do to evaluate you for possible PKD? A thorough history, looking for back or side pain, blood in the urine, kidney stones or urinary tract infections will be obtained. The doctor will ask about a family history of kidney disease or aneurysms. Sometimes, the doctor will find enlarged kidneys or liver when examining the abdomen. Your blood pressure will be measured. If PKD is suspected, a radiological imaging test, such as an ultrasound, “CAT” scan, or MRI, will be performed. Blood testing for the gene causing PKD (mutation screening) may be performed.

Most people with PKD have many years between first diagnosis and kidney failure. It is important to establish a good relationship with a doctor and, eventually, with a nephrologist to minimize progression of kidney failure and to effectively manage the complications of PKD. High blood pressure (hypertension) should be treated. Evidence suggests that some types of blood pressure medicine (ACE inhibitors or ARBs) may reduce urinary protein excretion and may slow or prevent progression of kidney failure. Side and back pain, as well as kidney stones, should be treated. Kidney infections are treated with care in PKD patients. Since not all antibiotics penetrate infected cysts, the doctor must select the best drugs to treat urinary infections. If kidney failure does develop, many PKD patients have had long and healthy lives with kidney transplantation or dialysis treatment.

Families with PKD often benefit from genetic counseling for up-to-date information on the inheritance of PKD, and the opportunity to discuss the particular issues of family planning for PKD families. This is often useful for individuals tested for PKD or couples contemplating having children.

The PKD Foundation, a non-profit organization, can provide useful information and opportunities to hear about others with PKD. Information about PKD, research and doctors is available through their Web site. Click here.

Alan S. Kliger, MD, is Clinical Professor of Medicine at Yale University School of Medicine, and Chairman of the Department of Medicine Hospital of St. Raphael, New Haven, Conn.

References:

1. Rizk D, Chapman AB. Cystic and Inherited Kidney Diseases; Amer. J Kidney Dis. 2003, 42:1305-1317.
2. Igarashi P, Somlo S, Ritz E. Genetics and Pathogenesis of Polycystic Kidney Disease; J Amer. Soc. Nephrology 2002; 13:2384-2398.
3. Yanaka K, Nagase S, Asakawa H et. al. Management of Unruptured Cerebral Aneurysms in Patients with Polycystic Kidney Disease. Surg Neurol. 2004 62:538-545.

This article originally appeared in the June/July 2005 issue of Kidney Beginnings: The Magazine, Vol. 4, No. 2.

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