Overview of Renal Cysts

Renal cysts, also known as kidney cysts, occur when fluid-filled sacs form on the kidneys. You might develop one cyst or multiple ones. The diagnosis, treatment, and symptoms of your cyst may depend on the type of renal cyst that you have.

Types

There are different types of renal cysts. A common type of cyst you may develop is called a simple cyst, which is encased in a thin wall. Usually, simple cysts don’t cause harm and they’re not likely to affect the size or function of the kidney. In fact, you might not know you have one until it’s picked up incidentally when undergoing tests for another procedure.

The other type of kidney cysts that can develop is due to a condition called polycystic kidney disease (PKD)—a genetic disorder that can run in families. Cysts associated with PKD can be inherited.

Renal cysts associated with PKD can lead to damage of the kidneys. Additionally, PKD can impair kidney function, elevate blood pressure, cause problems with blood vessels in the heart and brain, or cause cysts on the liver.

Risk Factors

It is unclear what causes renal cysts. However, they’re most common in older adults. Risk factors vary depending on the type of renal cyst at issue.

Regarding simple cysts, the risk factors that may make an individual more prone to developing them include:

• Being over the age of 40
• Being male

With PKD, your chances of developing the condition may increase if you already have a family member that’s been diagnosed with the condition.   

Signs and Symptoms

With simple cysts, you may not experience any symptoms related to it, according to a 2014 study. But in certain instances, a cyst may grow to the point where it becomes problematic. When this happens, the following signs and symptoms can occur:

• Hypertension or high blood pressure
• Pain in your abdomen back or side
• A detectable mass over the kidney area
• Obstructive uropathy, or a disruption in the normal flow of urine
• Hematuria, or blood in the urine

For PKD, the onset of the illness may begin years before you become symptomatic. The signs and symptoms associated with this disorder are similar to those of simple cysts, but may also include:

• Headaches
• An enlarged belly
• The feeling of fullness in the abdomen
• Kidney stones
• Infections of the urinary tract or kidneys
• Kidney failure

Causes

The cause of kidney cysts is unknown, though a few factors may play a part in the formation of simple cysts.

First, structures within the kidneys themselves may become blocked and impede the organ’s ability to collect urine properly. Second, insufficient blood flow to the kidneys may be associated with the development of renal cysts. Third, small sacs may form on the kidney’s tubules, and eventually, fill with fluid. Once they fill with fluid, they may detach and turn into cysts.

In PKD, the development of kidney cysts is linked to several genetic variants. Multiple dominant genes and one rare, recessive one harm the kidney tissue over time.

Diagnosis

Since most renal cysts aren’t problematic for people, they may not be diagnosed unless imaging tests are performed for other reasons. When they are discovered, additional imaging tests may be required to confirm whether the cyst is a simple cyst or a more severe medical issue. The tests that your healthcare provider might order include:

Ultrasound

A kidney ultrasound is a non-invasive and painless way to take pictures of your kidneys. During the ultrasound, sound waves that can’t be heard by human ears bounce off the organs and surrounding tissues and structures, producing images of the size and shape of your kidneys.  This allows your healthcare provider to identify the presence of cysts.

Kidney ultrasounds differ from X-rays in that they don’t involve radiation, so they’re safe for pregnant women, children, or people who might not tolerate dyes used in other imaging methods.

Computerized Tomography Scan (CT Scan)

CT scans create 3-D images using a combination of X-ray and computerized technology. In some cases, it may be necessary to inject a contrast dye to perform the test.

Complex cysts on a CT Scan can be classified by the Bosniak Scale;higher Bosniak numbers make the cysts more likely to become malignant.

Magnetic Resonance Imaging (MRI)

The way in which MRIs gather information to create images of the body is through radio waves and magnets. Like CT scans, some MRIs may require you to be injected with a contrast dye before the test. MRI is often used to further define complex benign cysts from malignant cysts. It can also be ordered prior to surgery to define anatomy.

Blood Tests

A blood test may be done to find out whether a cyst might be impeding the function of your kidneys.

Genetic Testing

If you’re diagnosed with PKD, and you’re thinking about having children, genetic testing might be done to find out whether your children are likely to inherit the condition.

Treatment

When simple kidney cysts aren’t causing symptoms, generally, no treatment is required. If the cyst is causing pain or impairing kidney function, the healthcare provider may need to perform a procedure to aspirate or drain the cyst. If the cyst is large, it may be necessary to surgically remove it.

If the cyst has lines/septations/or solid regions (making it a complex cyst), then additional management with further surveillance or removal may be indicated.

When there’s a diagnosis of PKD, treatment is aimed at maintaining the health of the kidney as best as possible. Medications for infections, like urinary tract infections, or high blood pressure, may reduce the rate at which kidney damage occurs.

Approximately 50% of people who have PKD develop chronic kidney disease, and subsequently, kidney failure. Usually, these people will need dialysis or a kidney transplant at some point in their lives.

A Word From Verywell

Knowing the different types of renal cysts can help you get the care you need. Since renal cysts are likely to go undetected. If you develop any of the symptoms associated with the condition, or you have a family history of PKD, see your healthcare provider to discuss screening, and, if necessary, treatment options.

If you receive a diagnosis that’s overwhelming to you, be sure to reach out to friends, family, an online or in-person group, or professionals for support—you don’t have to fight these health concerns alone.