Polycystic Kidney Disease
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Polycystic Kidney Disease

(PKD; Autosomal Dominant Polycystic Kidney Disease; ADPKD; Adult Polycystic Disease; Polycystic Kidney Disease Type 2)

En Español (Spanish Version)

Definition

The word polycystic means many cysts. Polycystic kidney disease (PKD) is an inherited disease that causes many cysts to form in the kidneys.

Cysts, which are sacs filled with fluid, grow in both kidneys causing them to become enlarged. The number of cysts can range from a few to a great number. The size of the cysts can vary from too small to detect, to cysts larger than the kidney itself.

PKD can be painful and interfere with the normal functioning of the kidney resulting in infection, kidney stones , high blood pressure , and, eventually, kidney failure . PKD is a potentially serious condition that requires care from your doctor.

The Kidney

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Causes

PKD is caused by an inherited gene. It is one of the most common genetic disease in the United States. Children have a 50% chance of developing PKD if one parent carries the gene. If a person has the PKD gene, he or she will have some form of the disease in his or her lifetime. The disease can cause different symptoms within members of the same family.

There is also a rare form of PKD, called autosomal recessive polycystic kidney disease, that affects newborns, infants, and children. This form of PKD can cause death in the first month of life.

Risk Factors

The primary risk factor for PKD is having a parent with the disease. Fifty percent of children born to a parent with the PKD gene develop the disease. In about 10% of cases, the gene for the disease was not inherited, but mutated. PKD affects men and women equally.

Symptoms

During the early stages of PKD, there are often no symptoms. Some people are never diagnosed because their symptoms are mild. Most symptoms appear in middle age.

Frequently, the first symptom is pain in the back or flank area. Other signs of PKD include:

If you experience any of these symptoms do not assume it is due to PKD. These symptoms may be caused by other, less serious health conditions. If you experience any one of them, see your physician.

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam. When diagnosing PKD, your doctor may begin by looking for signs of the disease, including high blood pressure, enlarged or tender kidneys, enlarged liver, and protein or blood in the urine.

An abdominal ultrasound is usually the test of first choice to detect the presence of cysts on the kidneys. If cysts are too small to be detected by ultrasound and the diagnosis is still in question, an abdominal CT scan or MRI scan may be performed.

If the diagnosis still remains unconfirmed, additional tests may be ordered, including:

  • Gene linkage study—a blood test that tests the DNA of the patient and family members with and without PKD
  • Direct DNA sequencing—blood sample of patient’s DNA to look for presence of the PKD gene

Ten to forty percent of patients with PKD also have an aneurysm (weakness in the wall of a blood vessel) in the brain. If you are diagnosed with PKD and there is a family history of a brain aneurysm, your doctor may recommend an arteriogram to detect the presence of an aneurysm.

Treatment

Most treatments for PKD treat the disease symptoms or prevent complications. Some of these treatment options may include:

  • High blood pressure medication—Since high blood pressure is common with PKD, antihypertensive medications are often prescribed to control blood pressure.
  • Pain medication—Pain medications must be used cautiously, since some of them can cause further damage to the kidneys.
  • Antibiotics—In the event of a urinary tract infection, aggressive treatment with antibiotics is required to avoid further damage to the kidneys.
  • Surgery—Cysts may be drained through surgery to relieve pain, blockage, infection, or bleeding. Cyst drainage may also temporarily lower blood pressure. Sometimes, one or both kidneys may be removed, called a nephrectomy , if pain is severe.
  • Diet—A low-protein diet may reduce stress on the kidney. Avoiding salt can help maintain normal blood pressure and drinking lots of water can help reduce the risk of kidney stones .
  • Dialysis and transplantation—More than half of PKD patients develop kidney failure and require dialysis . Dialysis is used to remove wastes from the blood, since the kidneys cannot. At this stage, dialysis will be a lifelong requirement unless a kidney transplant from a donor can be arranged and performed successfully.

Recent research has led to the development of several drugs that may prevent cysts from developing. An example is somatostatin, which has been studied in humans and may one day be available to prevent polycystic kidneys from developing.

Prevention

PKD is an inherited disease and is not preventable. If you have a family history of PKD, you may want to talk to your doctor about genetic testing.

RESOURCES:

American Academy of Family Physicians
http://www.familydoctor.org

PKD Foundation
http://www.pkdcure.org

CANADIAN RESOURCES:

BC Health Guide
http://www.bchealthguide.org

The Kidney Foundation of Canada
http://www.kidney.ab.ca

References:

An introduction to the kidneys and PKD. PKD Foundation website. Available at: http://www.pkdcure.org/site/PageServer?pagename=pkdabt_aboutpkd1 . Accessed January 13, 2008.

Autosomal dominant polycystic kidney disease. DynaMed website. Available at: http://dynamed102.ebscohost.com/Detail.aspx?/dynamed/c1c7ccfb117c2b04852562a2007b9a9d . Accessed January 13, 2008.

Chang MY, Ong AC. Autosomal dominant polycystic kidney disease: recent advances in pathogenesis and treatment. Nephron Physiol. 2007;108:1-7.

Polycystic kidney disease. US National Library of Medicine and the National Institutes of Health website. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/000502.htm . Accessed January 13, 2008.

Polycystic kidney disease (PKD). American Academy of Family Physicians website. Available at: http://familydoctor.org/142.xml?printxml . Accessed January 13, 2008.

Renal dysplasia and cystic disease. American Urological Association website. Available at: http://www.urologyhealth.org/adult/index.cfm? . Accessed January 13, 2008.

Tierney LM, McPhee SJ, Papadakis MA. Autosomal dominant polycystic kidney disease. Current Medical Diagnosis and Treatment . 44th ed. 2005.



Last reviewed January 2008 by Adrienne Carmack, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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