Q. I have two nieces who suffer with polycystic kidney disease. The girls’ mother is very concerned and wants to get more information. She wants her daughters, who live away from home, to be aware of anything they can do to minimize the effects of the disease. She’s also worried it might interfere with their ability to have children. Is this a maternal or paternal hereditary disease? What tests should the mother and father take to determine which side of the family should be concerned?
A. Polycystic kidney disease, or PKD, is one of the most common hereditary diseases in North America, affecting 1 to 2 of every 1,000 people. It’s also the fourth leading cause of kidney failure. Fortunately, it’s much less common than having a single cyst in the kidneys, which occurs in almost half of everyone over the age of 50.
In PKD, many fluid-filled cysts form in the filtering units, called nephrons, of both kidneys. Later they separate and grow, causing the kidneys to become enlarged but with less and less functional kidney tissue.
PKD is also a systemic disease, which means it can involve multiple organs and body tissues, including the liver, pancreas, arteries in the brain and the mitral valve.
The genetic defect that causes PKD is usually passed from one generation to another in an autosomal dominant manner. This means that if either parent has the defect, a child has a 50-50 chance of getting the abnormal gene. Fortunately, inheriting the abnormal gene doesn’t always mean you will get the disease.
In the autosomal dominant form of PKD, symptoms are not usually seen until early adulthood, ages 20 to 40. The disease is thought to affect men and women almost equally and occurs equally in all races.
This form of the disease progresses slowly over many years, often without symptoms. When symptoms do show up, they include dull back pain and headaches, blood in the urine, urinary infections, colicky pain due to kidney stones, and high blood pressure. The dull pain can be temporary or persistent, mild or severe.
A much less common form of PKD causes severe illness in children and progresses rapidly. It’s also inherited, but both parents must have a defective gene for it to occur.
Diagnosis is confirmed by imaging tests. CT scans and MRIs can detect cysts, but these more expensive tests are usually not required. Ultrasound, the passing of sound waves through the body to form a picture, is usually sufficient for diagnosis.
About half of adults with this form of PKD will eventually develop kidney failure. About half also will have cysts on the liver and high blood pressure. The high blood pressure can begin early in the disease, often before the cysts appear.
There is no known way to prevent PKD and no treatment for the underlying disease. However, the treatment of complications of PKD is relatively effective. Such treatment can ease symptoms and prolong life.
Timely treatment of urinary tract infections and high blood pressure, plus a low-protein diet, will slow progression of the disease. Those with kidney failure will require dialysis or kidney transplants.
Increased risk factors for development of kidney failure include an early diagnosis of PKD, hypertension, male gender and increased blood and protein in the urine.
A check of the medical literature did not turn up information about the impact of PKD on fertility and childbirth. It makes sense, however, to assume that even with the less severe form, if major symptoms occur prior to childbearing, that the disease and its treatment will have a negative effect.
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For more information, contact the Polycystic Kidney Research Foundation at 800-753-2873.
Write to Dr. Douma in care of the Chicago Tribune, Room 400, 435 N. Michigan Ave., Chicago, IL 60611.
