Kidney cysts

Kidney cysts are almost always benign lesions and are not cancerous. Majority of the individuals with kidney cysts will have no symptoms, and will go through life without even knowing that they have them.

Normal kidney function

The kidneys are the organs responsible for the production of urine/the liquid waste product of daily metabolism.

In addition to removing harmful waste products from the body, the kidneys also aid in the maintenance of the local environment (pH, levels of sodium, potassium, calcium etc.) around the cells of the body such as nerves, muscles, blood, etc; so that they can function properly.

In addition, the kidneys release three important hormones; erythropoietin, or EPO for stimulation of the bone marrow to make red blood cells, renin for regulation of blood pressure, and calcitriol for maintaining calcium for bones and for normal chemical balance in the body.

About Kidney Cysts

Sacs filled with water are seen to form in the kidney in some individuals as they grow older. These sacs are called as kidney cysts. They are usually small and oval or round in shape with thin walls. About 50 percent of individuals over the age of 50 years may have kidney cysts.

The risk of simple kidney cysts increases with advancing age although they can occur at any age. Kidney cysts are broadly classified as simple kidney cysts and polycystic kidney disease (PKD).

The simple kidney cyst is not an inherited condition. Cause for kidney cyst formation is not fully understood. It is seen to be more common as people age. Nearly 30 percent of people over the age of 70 have at least one simple kidney cyst.


Kidney cysts are benign sacs filled with watery fluid seen to occur in individuals with advancing age. While they are usually asymptomatic and do not cause any problems, they may be associated with serious complications in certain individuals and impair kidney function.

Simple kidney cysts are often incidentally 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. About 50 percent of the individuals who have PKD may however progress to kidney failure/end-stage renal disease (ESRD).

Simple cysts do not cause symptoms and also do not harm the kidney. In very rare cases, they may cause pain if they enlarge, become infected or start to bleed, or press on other organs. People with simple cysts are often seen to have high blood pressure, although the cause-and-effect relationship is not well understood.

Polycystic kidney disease (PKD) is an inherited condition that is characterized by the growth of numerous cysts in the kidneys. Not all the individuals with PKD will have symptoms.

Few of them may experience kidney cyst symptoms such as:

  • High blood pressure
  • Pain in the back and side
  • Blood in the urine
  • Frequent kidney infections
  • Fever
  • Abdominal pain
  • Dull pain over the back or side

PKD cysts can profoundly enlarge and replace much of the normal structure of the kidney over a period of time. This can cause reduction in the function of the kidney leading to kidney failure usually after many years.

About 50 percent of the individuals with PKD are seen to progress to kidney failure/end-stage renal disease (ESRD). Individuals with PKD can also have cysts in the liver and problems in other organs, such as blood vessels in the brain and heart.


Kidney cysts are usually accidentally found when an individual undergoes ultrasound of the abdomen, computerized tomography (CT), or magnetic resonance imaging (MRI) scans for any other health reason.

These imaging tests may also be used to diagnose simple kidney cysts. They help the doctor determine whether a kidney mass is a cyst or a tumor.

The doctor may order blood tests for assessment of kidney function. They can help in knowing whether a kidney cyst is impairing kidney function.

The doctor may ask for a detailed history regarding symptoms such as pain in the side between the ribs and hip, pain in the belly or back, fever, frequent urination, or blood in the urine or dark urine.

If the individual does not have the above mentioned symptoms, the simple kidney cyst is small, and is not interfering with kidney function then he/she may not need any treatment.

The doctor may suggest periodic imaging tests (every 6 to 12 months) such as ultrasound to see if the kidney cyst is enlarging. Sometimes, a simple kidney cyst may go away on its own. More frequent CT scans may be ordered in individuals with large kidney cysts or if the cyst contains calcifications/ hard stony pieces or dense tissue to look for early changes if any in the cyst.

If the kidney cyst changes and causes signs and symptoms then the individual may need to undergo treatment for the same.


An individual may need to undergo surgery for removal of a kidney cyst, if it is causing symptoms, is getting larger, or is interfering with kidney function.

Renal cyst treatment options may include puncturing the renal cyst and filling it with alcohol or surgery to remove the cyst. To puncture the cyst and cause it to shrink the doctor will insert a long, thin needle through the skin and through the wall of the kidney cyst. Then, he will drain the fluid from the cyst. Following this, the cyst is then filled with an alcohol solution to prevent it from reforming.

There are chances that the cyst in the kidney may reform in certain individuals who undergo this procedure.

Surgery is done in individuals with large cysts in order to drain and remove it. The surgeon will make several small incisions in the skin and insert special tools and a small video camera.

With the aid of a video monitor in the operating room, the surgeon guides the tools to the kidney and uses them to drain the fluid from the cyst. Then the walls of the cyst are cut or burned away.