Normally, the kidneys filter out excess toxic and waste substances and fluid from the blood. In people with polycystic kidney disease, the kidneys become enlarged with multiple cysts that interfere with normal kidney function. This can sometimes lead to kidney (renal) failure and the need for dialysis or kidney transplantation.
There are two major forms of polycystic kidney disease: autosomal dominant polycystic kidney disease and autosomal recessive polycystic kidney disease.
Autosomal dominant polycystic kidney disease (ADPKD) is a common disorder, occurring in approximately 1 in every 400 to 1000 people. Only about one-half of people with ADPKD will be diagnosed during the person's lifetime because the disease is often without symptoms. Autosomal dominant means that there is a 50 percent risk that an affected parent will pass the mutated gene to a child.
Autosomal recessive polycystic kidney disease (ARPKD, also called childhood polycystic kidney disease) is typically diagnosed in infancy, although less severe forms may be diagnosed later in childhood or adolescence. The estimated incidence is 1 in 10,000 to 20,000 people. Autosomal recessive means that the mutated gene must be present in both parents; a person who has only one abnormal gene is a carrier. If both parents are carriers (each having one abnormal and one normal gene), then there is a 25 percent chance that a child will inherit an abnormal gene from each and develop the disease.
The following is a discussion of autosomal dominant polycystic kidney disease, the most common cystic kidney disease
Hematuria is usually caused by bleeding into a cyst due to rupture of the cyst, which can occur as a result of a urinary tract infection or strenuous activity; bleeding can cause pain in the side of the low back (called flank pain). Patients with ADPKD can also develop kidney stones, which can cause hematuria and flank pain.
Hematuria related to bleeding cysts generally stops within two to seven days. The usual treatment includes bed rest and increasing fluids until the bleeding stops. If bleeding does not stop with bed rest and increased fluids, a procedure to stop the bleeding may be required.
Kidney stones — Kidney stones occur in up to 20 percent of people with polycystic kidney disease. Kidney stones may cause pain, or sometimes they can block the flow of urine without symptoms.
Treating kidney stones that block urine flow is difficult in patients with ADPKD. The cysts make it harder to surgically remove the stone or use shock waves to break up the stone (extracorporeal shock-wave lithotripsy or ESWL). (See "Patient information: Kidney stones in adults (Beyond the Basics)".)
Flank and abdominal pain — People with autosomal dominant polycystic kidney disease (ADPKD) often get flank and abdominal pain that is not related to infection, bleeding into a cyst, or a kidney stone. The pain is often dull and persistent and is thought to be caused by stretching of the wall of a cyst or pressure on other organs when the kidneys and/or liver are very large. In contrast, pain that begins suddenly is more likely to be caused by bleeding into or infection of a cyst, twisting of the kidney, or a kidney stone.
No specific treatment is required in most people with dull or persistent flank and abdominal pain; pain medications such as acetaminophen are often recommended. Nonsteroidal antiinflammatory drugs (NSAIDs), such as ibuprofen or naproxen, are sometimes recommended, although people with polycystic kidney disease should speak to their healthcare provider about the risks and benefits of NSAIDs before using them. NSAIDs are not recommended when kidney function is reduced.
Some people have persistent pain that is severe enough to limit their daily activities. Severe pain is usually evaluated with ultrasound to see if a large cyst is present in the area of pain. If so, ultrasound can be used to guide needle drainage of the cyst. Most people have significant relief of pain after drainage. However, pain commonly recurs and surgery is sometimes required to relieve the pressure of the cysts
