Are cysts on the kidneys serious?
Cysts on the kidneys are very common, and it’s important to have them properly evaluated for cancer, suggests Rishi Modh, MD, of St. Petersburg General Hospital. Watch this video to learn more.
Cysts of the kidneys are common in both men and women. Learn about the five categories of cysts and the treatment required for each. Watch this video with urologist Kyle Himsl, MD from Los Robles Hospital & Medical Center. 
Cysts on the kidney can be serious, depending on the degree of complexity, says Timothy Atkinson, MD, from Frankfort Regional Medical Center. Watch this video to find out why--and how cancer might be involved.
One should never have to worry about a kidney cyst, as long as it has been evaluated, says Kenneth Stallman, MD, with Methodist Specialist and Transplant Hospital. In this video, he explains the process if cysts are located in a complex area.
Anthony L. Komaroff, MD
Internal Medicine
Cysts are fluid filled structures that can be found in many organs. "Simple" cysts of the kidneys are very common, especially as we age. Simple cysts have a smooth border and clear fluid center.

Usually, simple cysts do not cause symptoms. Most often, these cysts are found when a person has an ultrasound or CT scan of the abdomen for some other reason. The radiologist's report would mention the presence of one or more cysts.

Simple cysts may develop when fluid from the urinary space leaks into the tissues of the kidney. Sometimes more than one cyst is seen in each kidney. (And they may vary in size.) Unless a simple cyst becomes very large, there is rarely any damage to the kidney.

To be certain that there is no other problem with the kidneys, your doctor may send you for a creatinine blood test and a urine test. The blood test is used to make you're your kidneys are functioning normally. The urine test, called a urinalysis, will detect any abnormal cells or proteins that could mean there is some kidney problem. If the blood and urine tests are normal, you won't need any other tests.

You want to be sure that you do have a simple cyst and not a "complex" cyst. Complex cysts contain some irregularity in appearance. They may contain blood or other material that might indicate a more serious problem. A person with a complex cyst needs to have a repeat CT scan or ultrasound in a few months. Or your doctor may refer you to a specialist for a potential biopsy.

Cysts in the kidneys are commonly detected using ultrasound, CT or MRI. Since 20-30% of adults can have kidney cysts, this is a common and important question to ask.

Kidney cysts can be classified as class 1, 2, 3 or 4. Radiologists and urologists have determined that the complexity of the cyst can be classified into one of the above categories, and then assigned a risk of it being cancer. Class 1 cysts are simple cysts with zero percent chance of cancer. Class 4 cysts are very complex appearing cysts with approximately 90% chance of cancer. Class 2 and 3 cysts lie somewhere in between, and urologic consultation is recommended to determine your cyst's complexity.

There are some people with genetic conditions such as adult polycystic kidney disease and others with the childhood onset variant, characterized by dozens of cysts in both kidneys, and also in the liver. These diseases are far more serious and warrant close medical attention.

Continue Learning about Kidney Disease Symptoms

Kidney Disease Symptoms

Kidney Disease Symptoms

Kidney disease develops over time and typically has no symptoms until it has progressed. Common symptoms include fatigue, dry, itchy skin, headaches, protein in the urine, nausea, weight loss and high blood pressure.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.