Autosomal dominant PKD is usually diagnosed by kidney imaging studies. The most common form of diagnostic kidney imaging is ultrasound, but more precise studies, such as computerized tomography (CT) scans or magnetic resonance imaging (MRI) are also widely used. In autosomal dominant PKD, the onset of kidney damage and how quickly the disease progresses can vary. Kidney imaging findings can also vary considerably, depending on a patient's age. Younger patients usually have both fewer and smaller cysts. Doctors have therefore developed specific criteria for diagnosing the disease with kidney imaging findings, depending on patient age.
In most cases of autosomal dominant PKD, patients have no symptoms and their physical condition appears normal for many years, so the disease can go unnoticed. Physical checkups and blood and urine tests may not lead to early diagnosis. Because of the slow, undetected progression of cyst growth, some people live for many years without knowing they have autosomal dominant PKD.
Once cysts have grown to about one-half inch, however, diagnosis is possible with imaging technology. Ultrasound, which passes sound waves through the body to create a picture of the kidneys, is used most often. Ultrasound imaging does not use any injected dyes or radiation and is safe for all patients, including pregnant women. It can also detect cysts in the kidneys of a fetus, but large cyst growth this early in life is uncommon in autosomal dominant PKD.
More powerful and expensive imaging procedures such as CT scans and MRI also can detect cysts. Recently, MRI has been used to measure kidney and cyst volume and monitor kidney and cyst growth, which may serve as a way to track progression of the disease.
An ultrasound imaging device passes harmless sound waves through the body to detect possible kidney cysts.
Diagnosis can also be made with a genetic test that detects mutations in the autosomal dominant PKD genes, calledPKD1 and PKD2. Although this test can detect the presence of the autosomal dominant PKD mutations before large cysts develop, its usefulness is limited by two factors: detection of a disease gene cannot predict the onset of symptoms or ultimate severity of the disease, and if a disease gene is detected, no specific prevention or cure for the disease exists. However, a young person who knows of a PKD gene mutation may be able to forestall the loss of kidney function through diet and blood pressure control. The genetic test may also be used to determine whether a young member of a PKD family can safely donate a kidney to a family member with the disease. Individuals with a family history of PKD who are of childbearing age might also want to know whether they have the potential of passing a PKD gene to a child. Anyone considering genetic testing should receive counseling to understand all the implications of the test.
The chance of a child being affected by ADPKD when one parent is affected is one in two (50 percent chance). Although a child of a person with ADPKD can be screened for the disease before symptoms develop, screening is not usually recommended during childhood unless the child has signs or symptoms of the disease. Affected children may not yet have cysts that are visible by ultrasound; even if cysts were seen, learning of the diagnosis during childhood would not change the child's medical treatment, but could potentially cause the child to worry. However, children with an affected parent should see a physician regularly and have their blood pressure monitored and a urinalysis performed. Children should also be followed for kidney infections, blood in the urine, kidney stones, and the presence of hernias.
Chronic Kidney Disease
Chronic kidney disease (CKD) is a condition characterized by a gradual loss of kidney function over time. To read more about kidney function, see How Your Kidneys Work. CKD is also known as chronic renal disease.
Chronic kidney disease includes conditions that damage your kidneys and decrease their ability to keep you healthy by doing the jobs listed. If kidney disease gets worse, wastes can build to high levels in your blood and make you feel sick. You may develop complications like high blood pressure, anemia (low blood count), weak bones, poor nutritional health and nerve damage. Also, kidney disease increases your risk of having heart and blood vessel disease. These problems may happen slowly over a long period of time. Chronic kidney disease may be caused by diabetes, high blood pressure and other disorders. Early detection and treatment can often keep chronic kidney disease from getting worse. When kidney disease progresses, it may eventually lead to kidney failure, which requires dialysis or a kidney transplant to maintain life.
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Kidney transplantation is considered the treatment of choice for many people with severe chronic kidney disease because quality of life and survival are often better than in people who use dialysis. However, there is a shortage of organs available for donation. Many people who are candidates for kidney transplantation are put on a transplant waiting list and require dialysis until an organ is available. Not everyone is a candidate for transplant, but your doctor will discuss this with you.
As the kidneys lose their ability to function, fluid and waste products begin to build up in the blood. Dialysis should begin before kidney disease has advanced to the point where life-threatening complications occur. This usually takes many months or years after kidney disease is first discovered, although sometimes severe kidney failure is discovered for the first time in people who were not previously known to have kidney disease.
It is best to begin dialysis treatments when you have advanced kidney disease, but while you still feel well and have no or only mild symptoms of kidney failure. Such symptoms include nausea, loss of appetite, loss of energy, vomiting, and others. You and your doctor will decide when to begin dialysis after considering a number of factors, including your kidney function (as measured by blood and urine tests), overall health, and personal preferences.
ADPKD usually commences in utero but there may be several decades before symptoms or signs of disease emerge. Screening offers a means of detecting asymptomatic individuals. There should be appropriate counseling prior to screening.
Benefits of testing include:
- Family planning and reproductive choice.
- Early detection and treatment of disease complications.
- Selection of unaffected family members for living donor transplantation.
Risks of testing include:
- Possible discrimination in terms of insurance and employment.
- Psychological effects of living with a disease without effective treatment.
Screening of asymptomatic children is not currently advocated, as the removal of their choice to know and possible adverse effects of the diagnosis are thought to outweigh benefits. However, this is controversial and many argue for earlier screening with more reliable ultrasound scanning and likely benefits of early detection of hypertension.