Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common forms of inherited kidney disease. It is caused by a faulty gene that causes cysts—fluid-filled lumps on the body—to develop in the kidneys.
Who gets ADPKD?
ADPKD is a genetic condition in which a faulty gene is passed from a parent with ADPKD to a child. It has an autosomal dominant pattern of inheritance, meaning that each child of a parent with ADPKD has a 50% chance of inheriting the disease. Boys and girls are equally affected. Approximately 1 in 10 people diagnosed with ADPKD have no family history of ADPKD.
How does ADPKD affect the kidneys?
Healthy kidneys remove waste products and excess fluid from the blood and help control blood pressure. With ADPKD, cysts form in the kidneys and can grow over time. The cysts put pressure on the kidney and slowly replace the normal kidney tissue and, over time, can disrupt kidney function. Eventually, there is not enough normal kidney tissue to clean (filter) the blood. The growing cysts eventually lead to kidney failure.
ADPKD usually progresses very slowly. Symptoms most commonly do not develop until adulthood, often around 40 or 50 years of age. However, the degree of cyst formation and kidney damage varies from one person to another. About 1 in 3 people with ADPKD reach the age of 70 without any serious symptoms of kidney disease, while some teenagers can experience problems.
What are the symptoms of ADPKD?
Symptoms of ADPKD are much less common in children than adults. Some possible symptoms include:
Visible blood in the urine
Headache from high blood pressure, though most people with high blood pressure do not have symptoms
Pain over the kidneys
Sudden, severe pain in the back or lower belly due to a kidney stone
Back pain or pain when urinating, due to a urinary tract infection
Pain or fullness in the abdomen
Fatigue or lack of appetite can occur with severe kidney failure
What are the complications of ADPKD?
Complications related to the kidneys include:
There are also potential complications in other organs, although these are much less common:
About 1 in 10 people with ADPKD can develop a localized swelling of a blood vessel in the brain (called an aneurysm). It is more common in patients with ADPKD who have a family history of brain aneurysm. In most cases, these aneurysms do not cause symptoms. However, there is a risk of rupture of the blood vessel which can be very serious.
Preeclampsia during pregnancy
Mitral valve prolapse: One of the heart valves does not close properly, which may result in the backflow of blood within the heart
Cysts in other organs. This most commonly occurs in the liver, but rarely occurs in childhood and they seldom cause symptoms or complications, even in adults.
How is ADPKD diagnosed?
When ADPKD is suspected, the following tests can be done to help confirm the diagnosis:
Kidney ultrasound: An ultrasound can diagnose ADPKD by detecting cysts in the kidneys before they cause symptoms.
Some doctors recommend screening by ultrasound for family members of ADPKD patients, every five years from late childhood until the age of 30. At 30 years of age, a normal ultrasound makes it very unlikely that someone has ADPKD.
Abdominal CT scan or MRI: these tests are better than an ultrasound in their ability to detect small cysts, but are not typically done due to radiation exposure or cost.
Genetic testing: A blood test can be used to screen for the gene that causes ADPKD in younger people before cysts are detectable by ultrasound. This test is not perfect so some people with ADPKD may still have a negative test.
How is ADPKD treated?
Children with ADPKD are usually symptom-free for many years. No particular treatment is needed at this point. Early detection and treatment of high blood pressure, if present, are important. Good blood pressure control with a low salt diet, exercise, maintenance of normal body weight, and medications can slow down the progression of kidney damage in patients with ADPKD.
Increased fluid intake may be helpful in slowing the rate of cyst growth. In addition, a drug called tolvaptan was approved by the FDA and has been shown to slow the decline of kidney function in adults with rapidly progressive ADPKD. It works to slow the growth of the cysts, however tolvaptan is not currently approved for use in patients with ADPKD under 18 years of age.
There are no treatments at this time that can reverse the growth of the cysts.
Should I get my children tested for ADPKD if I have a family history of ADPKD?
You should first discuss with your pediatrician whether your child is at risk for having ADPKD. In most cases, if one of the child's parents has ADPKD, the child is at risk. In some cases, the parent may be at risk of having ADPKD, but it is unknown whether the parent has ADPKD. Since the decision to screen a child at risk for ADPKD can be complex, it can be helpful to meet with a pediatric kidney specialist (nephrologist).
Children who are diagnosed with ADPKD may benefit from monitoring and treatment. However, children who are not screened but are at risk also require close monitoring since it is important to detect complications of ADPKD that may occur in childhood. If there are complications, then screening may be recommended in a child who has not previously been screened.
All children with ADPKD and those who are at risk for ADPKD should have regular monitoring of their urine and blood pressure. Kidney function may also be tested periodically.
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