|Polycystic Kidney Disease
Polycystic kidney disease (PKD) is a disorder in which clusters of cysts develop primarily within your kidneys. Cysts are noncancerous round sacs containing water-like fluid.
Polycystic kidney disease isn't limited to only your kidneys, although the kidneys usually are the most severely affected organs. The disease can cause cysts to develop elsewhere in your body.
The greatest risk for people with polycystic kidney disease is developing high blood pressure. Kidney failure also is common with polycystic kidney disease.
Polycystic kidney disease varies greatly in its severity, and some complications are preventable. Regular checkups can lead to treatments to reduce damage to your kidneys from complications, such as high blood pressure.
Cysts are noncancerous (benign), round sacs that contain water-like fluid. They vary in size from tiny sacs to sacs large enough to hold several quarts of fluid. Having one or more benign kidney cysts is common, especially in people older than 50. A benign, simple kidney cyst doesn't require treatment. And having one or more kidney cysts doesn't mean you have polycystic kidney disease.
Abnormal genes cause polycystic kidney disease, and the genetic defects mean the disease runs in families. The
disease has two types, caused by different genetic flaws :
- Autosomal dominant polycystic kidney disease (ADPKD). Signs and symptoms of this form often develop between the ages of 30 and 40. In the past, this type was called adult polycystic kidney disease, but in a small number of cases children do develop the disorder. Only one parent needs to have the disease in order for it to pass along to the children. If one parent has ADPKD, each child has a 50 percent chance of getting the disease. This form accounts for 85 percent to 90 percent of cases of polycystic kidney disease.
- Autosomal recessive polycystic kidney disease (ARPKD). This form is far less common than ADPKD, occurring only in one in 10,000 to 20,000 births in the United States. The signs and symptoms often appear shortly after birth. Sometimes, symptoms don't appear until later in childhood or during adolescence. Both parents must have abnormal genes to pass on this form of the disease. If both parents carry the genes for this disorder, each child has a 25 percent chance of getting the disease.
Research has identified two genes associated with ADPKD and one associated with ARPKD. Though it hasn't been identified, scientists suspect there is a third gene responsible for some forms of ADPKD.
In about 25 percent to 40 percent of cases, a person with ADPKD has no known family history of the disease. In most cases, someone in the affected person's family did have the disease, but didn't show signs or symptoms before dying of other causes. In a smaller percentage of cases where no family history is present, ADPKD results from a spontaneous gene mutation.
Effects beyond your kidneys
Polycystic kidney disease isn't limited to only your kidneys, although the kidneys usually are the most severely affected organs. The disease can cause cysts to develop in your liver, pancreas, membranes that surround your brain and central nervous system, and seminal vesicles.
When to seek medical advice
It's not uncommon for people to have polycystic kidney disease for years without developing signs or symptoms and without knowing they have the disease.
If you exhibit some of the signs and symptoms of polycystic kidney disease, which include high blood pressure, an increase in the size of your abdomen, blood in your urine, back or side pain, or kidney stones, see your doctor to determine what might be causing them. If you have a first-degree relative — parent, sibling or child — with ADPKD, see your doctor to discuss the pros and cons of screening for this disorder.
Polycystic kidney disease symptoms may include :
- High blood pressure
- Back or side pain related to enlarged kidneys
- Abdominal pain
- Increase in the size of your abdomen
- Blood in your urine
- Frequent urination
- Kidney stones
- Kidney failure
- Kidney infections
Several diagnostic methods are available to detect the size and number of cysts as well as to evaluate the amount of healthy kidney tissue.
- Ultrasound examination. This is the most commonly used diagnostic method. A wand-like device called a transducer is placed on your body. It emits inaudible sound waves that are reflected back to the transducer — like sonar. A computer translates those reflected sound waves into a moving image of your kidneys.
- Computerized tomography (CT) scan. As you lie on a movable table, you're guided into a big doughnut-shaped device that passes very thin X-ray beams through your body. Your doctor is able to see cross-sectional images of your kidneys.
- Magnetic resonance imaging (MRI) scan. As you lie inside a large cylinder, magnetic fields and radio waves generate cross-sectional views of your kidneys.
- Genetic testing. Gene linkage analysis involves special blood tests for you and for at least three family members who are known either to have or not to have polycystic kidney disease. Then, the results of your blood tests are compared with the results of the tests of your family members. Because this test is so expensive, it's often only used when one family member is considering donating a kidney to another family member.
High blood pressure is a common complication of polycystic kidney disease. Untreated, high blood pressure can cause further damage to your kidneys and increase your risk of heart disease and stroke.
Loss of kidney function
Progressive loss of kidney function is one of the most serious complications of polycystic kidney disease. Nearly half of those with the disease have kidney failure by age 60, and up to 75 percent will have kidney failure by age 70. If you have high blood pressure or blood or protein in your urine, you have a greater risk of kidney failure.
Polycystic kidney disease causes your kidneys to gradually lose their ability to eliminate wastes from your blood and maintain your body's balance of fluids and chemicals. As the cysts enlarge, they produce pressure and promote scarring in the normal, unaffected areas of your kidneys. These effects promote high blood pressure and interfere with the ability of your kidneys to keep wastes from building to toxic levels, a condition called uremia.
As the disease worsens, end-stage kidney (renal) failure may result. When end-stage renal failure occurs, you'll need ongoing kidney dialysis or a transplant to prolong your life.
Other complications of polycystic kidney disease may include :
- Pregnancy complications. Most women with polycystic kidney disease can have an uneventful pregnancy. Others may develop a life-threatening disorder called preeclampsia. Those most at risk are women who have high blood pressure before they become pregnant.
- Growth of cysts in your liver. The likelihood of developing liver cysts for someone with polycystic kidney disease increases with age. More than three-quarters of people with PKD develop liver cysts at some point in their lifetimes. While both men and women develop cysts, women often develop larger cysts and get them at an earlier age. Cyst growth appears to be aided by female hormones. Liver cysts are more frequent in women who've been pregnant.
- Development of an aneurysm in your brain. Localized enlargement of an artery in your brain can cause a hemorrhage if it ruptures. Aneurysms tend to run in families and are present in between 4 percent and 10 percent of people with polycystic kidney disease.
- Heart valve abnormalities. As many as one-quarter of adults with polycystic kidney disease develop mitral valve prolapse. When this happens, the valve no longer closes properly, which allows blood to leak backward.
- Colon problems. You may develop hernias, and pouches or sacs in the wall of the colon (diverticulosis).
- Chronic pain. Pain is a common symptom for people with polycystic kidney disease. It often occurs in your side or back.
Treating polycystic kidney disease involves dealing with the following signs, symptoms and complications :
High blood pressure. Controlling high blood pressure may delay the progression of the disease and slow further kidney damage. Combining a low-sodium, low-fat diet that's moderate in protein and calorie content along with eliminating smoking, increasing exercise and reducing stress may help control high blood pressure.
However, medications are often usually needed to control high blood pressure. Medications called angiotensin-converting enzyme (ACE) inhibitors are frequently used to control high blood pressure in people with polycystic kidney disease.
- Pain. Chronic pain, usually located in your back or your side, is a common symptom of polycystic kidney disease. Often, the pain is mild and you can control it with over-the-counter medications containing acetaminophen. For some people, however, the pain is more severe and constant. In rare cases, your doctor may recommend surgery to remove cysts if they're large enough to cause pressure and pain.
- Complications of cysts. Rarely, when kidney cysts cause obstruction of other organs or veins, you may need to undergo surgery to drain the cysts.
- Bladder or kidney infections. Prompt treatment of infections with antibiotics is necessary to prevent kidney damage.
- Blood in the urine. You'll need to drink lots of fluids as soon as you notice blood in your urine, in order to dilute the urine. Dilution may help prevent obstructive clots from forming in your urinary tract. Bed rest also may help decrease the bleeding.
- Kidney failure. If your kidneys lose their ability to remove wastes and extra fluids from your blood, you'll eventually need either dialysis or a kidney transplant.
- Liver cysts. Nonsurgical management of liver cysts includes avoidance of hormone replacement therapy. Other options in rare cases include drainage of symptomatic cysts if they're not too numerous, partial removal of the liver or even liver transplantation.
- Aneurysms. If you have polycystic kidney disease and a family history of ruptured intracranial aneurysms, your doctor may recommend regular screening for intracranial aneurysms. If an aneurysm is discovered, surgical clipping of the aneurysm to reduce the risk of bleeding may be an option, depending on its size. Nonsurgical treatment of small aneurysms may involve controlling high blood pressure and high cholesterol and quitting smoking.