Kidney cysts Overview
Kidney cysts are round pouches of fluid that form in the kidneys. Kidney cysts can be associated with serious disorders that may impair kidney function. But more commonly, kidney cysts are a type called simple kidney cysts noncancerous cysts that rarely cause complications.
It’s not clear what causes simple kidney cysts. Typically, only one cyst occurs on the surface of a kidney, but multiple cysts can affect one or both kidneys. However, simple kidney cysts aren’t the same as the cysts that form with polycystic kidney disease.
Simple kidney cysts are often detected during an imaging test being done for another condition. Simple kidney cysts that don’t cause signs or symptoms usually don’t require treatment.
Simple Kidney Cysts Causes
The cause of simple kidney cysts is not fully understood, but they do not appear to be inherited. Being male is a risk factor, however, as is age: Almost half of all people over the age of 50 have one or more simple cysts in the kidneys. The size of these cysts may also increase with age, which may double over 10 years.
How common are kidney cysts?
Up to 50 percent of people older than 50 years of age have kidney cysts.
How are simple kidney cysts diagnosed?
Most simple kidney cysts are found during imaging tests done for other reasons. When a cyst is found, the following imaging tests can be used to determine whether it is a simple kidney cyst or another, more serious condition. These imaging tests are performed at an outpatient center or hospital by a specially trained technician, and the images are interpreted by a radiologist a doctor who specializes in medical imaging. Ultrasound may also be performed in a health care provider’s office. Anesthesia is not needed though light sedation may be used for people with a fear of confined spaces who undergo magnetic resonance imaging (MRI).
- Ultrasound. Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure. An abdominal ultrasound can create images of the entire urinary tract. The images can be used to distinguish harmless cysts from other problems.
- Computerized tomography (CT) scan. CT scans use a combination of x rays and computer technology to create three-dimensional (3-D) images. A CT scan may include the injection of a special dye, called contrast medium. CT scans require the person to lie on a table that slides into a tunnel-shaped device where the x rays are taken. CT scans can show cysts and tumors in the kidneys.
- MRI. MRI machines use radio waves and magnets to produce detailed pictures of the body’s internal organs and soft tissues without using x rays. An MRI may include the injection of contrast medium. With most MRI machines, the person lies on a table that slides into a tunnel-shaped device that may be open ended or closed at one end; some newer machines are designed to allow the person to lie in a more open space. Like CT scans, MRIs can show cysts and tumors.
What are the symptoms of simple kidney cysts?
Simple kidney cysts usually don’t cause any symptoms. In fact, most people who have them don’t know they have them. The cysts become a problem if they rupture (break open) and start to bleed, become infected, or grow so large that they push against other organs within the abdomen.
When simple kidney cysts do cause symptoms, they might include:
- Pain in the side between the ribs and hip, stomach, or back
- Fever
- Frequent urination (having to go the bathroom often)
- Blood in the urine, or dark urine
Depending on where the cyst is located, it can affect how the kidney works. It can also lead to a type of high blood pressure if the cyst prevents the kidney from filtering extra fluid from the blood.
Kidney Cysts Treatment
- Asymptomatic cases may benefit from modest dietary changes as well as prescription medications, in particular ACE inhibitors or ARBs (angiotensin receptor blockers).
- Antibiotics may be prescribed to treat associated urinary tract infections.
- Antihypertensive drugs are prescribed to treat associated high blood pressure.
- Rarely, needle aspiration, in which the doctor inserts a needle into the kidney to drain an enlarged or painful cyst, may be done.
- Dialysis is necessary should kidney failure occur. This procedure filters the blood artificially, removing waste products and excess fluid when the kidney can no longer perform these functions.
- A kidney transplant is an alternative to dialysis in cases of kidney failure.
