Kidney cysts are round pouches of fluid that form on or in the kidneys. Kidney cysts can occur with disorders that may impair kidney function. But more often, kidney cysts are a type called simple kidney cysts. Simple kidney cysts aren’t cancer and rarely cause problems.

It’s not clear what causes simple kidney cysts. Often, one cyst occurs on the surface of a kidney. But more than one cyst can appear on one or both kidneys. Simple kidney cysts aren’t the same as cysts that form with polycystic kidney disease. Simple cysts also differ from complex cysts. Complex cysts need to be watched for changes that could be cancer.

Simple kidney cysts are often found during an imaging test for another condition. Treatment usually isn’t needed unless simple cysts cause symptoms.

Simple kidney cysts typically don’t cause symptoms. But if a simple kidney cyst grows large enough, symptoms may include:

When to see a doctor

Make an appointment with your health care provider if you have symptoms of a kidney cyst.

It’s not clear what causes simple kidney cysts. One theory suggests that kidney cysts develop when the surface layer of the kidney weakens and forms a pouch. The pouch then fills with fluid, detaches and develops into a cyst.

The risk of having simple kidney cysts increases as you get older. But they can occur at any age. Simple kidney cysts are more common in men.

Kidney cysts may sometimes lead to complications, including:

Tests and procedures used to diagnose simple kidney cysts include:

Treatment may not be needed

If a simple kidney cyst causes no symptoms and doesn’t affect kidney function, you may not need treatment. Instead, your health care provider may recommend that you have imaging tests, such as ultrasounds, over time to see whether your kidney cyst changes.

If your kidney cyst changes and causes symptoms, you may choose to have treatment at that time. Sometimes a simple kidney cyst goes away on its own.

Treatments for cysts that cause symptoms

If a simple kidney cyst is causing symptoms, your health care provider may recommend treatment. Options include:

Some procedures to treat a kidney cyst may require a brief hospital stay.

A simple kidney cyst found during an imaging test for another disease or condition may concern you. Talk with your health care provider about what having a simple kidney cyst means for your health. Gathering information may put your mind at ease and help you feel more in control of your situation.

What you can do

Before meeting with your health care provider, prepare a list of questions to ask, such as:

Don’t hesitate to ask other questions as they occur to you during your appointment.

What to expect from your doctor

Your health care provider is likely to ask you a number of questions, such as:

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