top of page


What are Kidney Cysts And What Causes Them?

kidney cysts

Kidney cysts (renal cysts) are oval shaped or round, thin-walled sacs or pouches on the kidneys that usually contain liquid or semisolid material.  They vary widely in size, but most are usually small. 

In many cases cysts on the kidneys are so small that they can only be seen clearly under a microscope.  In some cases, cysts are present at birth (congenital).  This occurs approximately 1 in every 4,000 births.  In other cases, they develop over a period of time and are usually caused by tubular obstructions.

Renal cysts may develop singly or as a group and can affect one or both kidneys.

What Are The Health Risks of Kidney Cysts?

A single cyst is usually not a major health risk and is quite common in persons over the age of 50.  In most cases, these cysts are almost always benign (not cancerous) and do not affect normal kidney function.  Treatment is not normally required.

While it is possible for cancer or infection to develop in a single cyst, such complications are rare.  One major concern with an extremely large cyst is that it can replace much of the mass of the kidney, which can lead to kidney failure.

With multiple cysts, however, the likelihood of complications is much greater.  This is the case with a condition known as polycystic kidney disease.  This condition results in the formation of multiple cysts on the kidney, which can present some complications and is very difficult to treat.

Polycystic kidney disease may lead to the formulation of hundreds of cysts, enlarged kidneys and eventually kidney failure.  This condition is a commonly inherited disorder.  Some children are born with it while others develop it early in life.  Most often, however, the symptoms of polycystic kidney disease are not manifested until the age of 30 to 40 years of age.


There are usually no symptoms of a single benign cyst.  If, however, the cyst is unusually large, symptoms such as back pain or abdominal pain may develop.  Occasionally, infections can occur, causing pain when passing urine, or fever, sweats and pain in the back.

In the case of polycystic kidney disease, general symptoms include:

  • blood in the urine;

  • pain or tenderness in the back or abdomen;

  • in infants, there may be abdominal or flank masses;

  • frequent urination;

  • burning on urination;

  • fatigue, and

  • swollen ankles.

Kidney Cysts Treatment

Treatment is not usually required for small single benign cysts. Antibiotics are used, if a cyst becomes infected. Sometimes these are hard to treat, requiring long courses of antibiotics.

If the cyst is unusually large it could impair kidney function and lead to kidney failure. A physician may choose to collapse or decompress a large Kidney cyst. This is done by inserting a needle, guided by ultrasound or x-rays, through the skin and into the cyst. This procedure requires some local anesthetic to dull the pain.

In extreme cases, particularly if severe infection or cancer has caused irreversible damage, the whole kidney can be removed by an operation. The patient is still able to lead a normal healthy life, if the other kidney is healthy.

If complications, due to renal cysts, result in kidney failure, dialysis may be necessary. A kidney transplant may become necessary in cases of end stage renal disease.

There is yet no known cure for kidney cysts. The goals of various treatments administered are to preserve kidney function as long as possible, prevent or treat complications, and to alleviate symptoms. Thankfully, most cases of this kidney disease involve a single cyst, which are not normally a major health risk. In most cases it creates no problems and requires no treatment.

bottom of page