People with simple kidney cysts have sacs that are filled with fluid within their kidneys. It is possible to have one or more cysts in one or both kidneys. The exact cause of simple kidney cysts is not known but they tend to be more common as people age. Simple kidney cysts rarely cause problems and are different from polycystic kidney disease, which tends to run in families and can be more serious.
The cause of simple kidney cysts is not fully understood. Obstruction of tubules tiny structures within the kidneys that collect urine or deficiency of blood supply to the kidneys may play a role. Diverticula sacs that form on the tubules may detach and become simple kidney cysts.
Simple kidney cysts usually do not cause symptoms. In most cases, a doctor finds them during an ultrasound or computerized tomography (CT) scan done for another reason. However, simple kidney cysts may:
- Cause pain in your side, back, or upper abdomen if they enlarge and press on other organs
- Become infected, causing fever, chills, or other signs of infection
- Impair kidney function (rare)
Simple kidney cysts have been associated with high blood pressure, but it is unclear what the relationship is between the two.
Tests and procedures used to diagnose simple kidney cysts include:
- Imaging tests. Imaging tests, such as an ultrasound, a computerized tomography (CT) scan and magnetic resonance imaging (MRI), are often used to investigate simple kidney cysts. Imaging tests can help your doctor determine whether a kidney mass is a cyst or a tumor.
- Kidney function tests. Testing a sample of your blood may reveal whether a kidney cyst is impairing your kidney function.