The kidneys play essential roles in health by filtering blood and enabling the removal of waste products via urine. Kidney cysts (also known as renal cysts) are fluid-filled sacs found in one or both kidneys. Kidney cysts can be present for various reasons, including genetic and environmental factors. They are almost always benign, meaning they will not become cancerous. However, in rare cases, malignancy can occur. Even though they typically do not become cancerous, kidney cysts can cause a variety of health issues by interfering with normal kidney function. In severe cases, kidney cysts can lead to kidney failure, which is a life-threatening condition requiring immediate medical care and even kidney transplantation.
Kidney cysts are often identified incidentally (by accident) during imaging tests for other conditions. This article will provide a broad overview of kidney cysts, including the different types, their causes and symptoms, how they are diagnosed, and when to seek medical attention.
There are two main types of kidney cysts: simple kidney cysts and complex kidney cysts. Simple cysts are the most common type and are usually benign. They typically do not cause any symptoms, though they can sometimes emerge. Complex kidney cysts have irregular features, which makes them more concerning from a healthcare perspective. These features can include thickened walls and solid internal structures. These cysts often require follow-ups and closer monitoring because they can potentially be cancerous or lead to other complications, such as infection, bleeding, or impaired kidney function.
Kidney cysts are very common and occur in roughly 25 percent of the population over the age of 40. The incidence of kidney cysts increases with age, and individuals can have many kidney cysts at once. Kidney cysts are typically found incidentally during imaging procedures to assess other conditions. The majority of kidney cysts are benign. However, it’s essential to evaluate each cyst to determine its potential health risks. In rare cases, cysts can become cancerous or lead to impaired kidney function.
Other than potentially becoming cancerous, kidney cysts can rupture or become infected, causing significant pain and leading to potentially life-threatening complications. If kidney cysts grow to a certain size, they can put physical pressure on nearby organs, which can cause significant discomfort.
Genetic factors can play a role in the development of kidney cysts. A primary example is a condition known as polycystic kidney disease (PKD), in which an individual develops several cysts in the kidneys. Individuals with this condition can develop cysts at any age, including before birth. Hereditary cystic conditions are typically diagnosed by genetic testing and determining if there is a family history of kidney cysts. Early diagnosis can allow individuals and clinicians to take corrective action before severe complications emerge.
As previously discussed, the emergence of kidney cysts becomes increasingly likely as we age. Over half of those over fifty are expected to have at least one kidney cyst. Kidney cysts arise due to the natural aging process of the kidneys and are typically benign and asymptomatic. However, these cysts can cause symptoms when they grow above a certain size. Simple renal cysts are known to double in size over the course of a decade.
Kidney cysts can emerge for reasons other than genetics and age. They are also associated with chronic kidney disease, dialysis, and kidney injury. Sources of kidney injury that can lead to the generation of cysts include exposure to nephrotoxic (toxic to the kidneys) drugs and ischemia-reperfusion, which occurs when blood flow returns to tissue after it’s been cut off, causing damage due to sudden inflammation and stress on the cells. In some cases, the cause of kidney cysts is clear; however, in many cases, it is likely a combination of several factors. Understanding the underlying causes can help when directing medical care.
Most kidney cysts are asymptomatic, and individuals with them can live their entire lives completely unaware and without experiencing even mild discomfort. The lack of symptoms means that kidney scans are rarely performed to look specifically for cysts. Instead, cysts are usually identified when monitoring other health issues. It’s important to note that asymptomatic cysts typically do not require treatment. However, clinicians may monitor them over time if the cysts have abnormal properties.
It's essential to recognize the symptoms of kidney cysts, as they can signal the need for treatment to prevent the condition from worsening. When kidney cysts grow to a certain size, they can cause symptoms such as discomfort, pain or aching in the sides of the abdomen or back, fever, or a frequent need to urinate. Other and often more worrying symptoms include blood in urine, high blood pressure, and feelings of fullness in the abdomen.
It’s important to seek medical attention if you experience persistent or severe symptoms, including those mentioned above. Unexplained changes in urinary habits are important to look out for as they are often associated with a range of severe health conditions, including prostate problems and bladder cancer. Clinicians will evaluate your symptoms promptly and decide whether further investigations, such as imaging tests, are warranted.
Imaging techniques to assess kidney cysts include ultrasounds, computed tomography (CT), and magnetic resonance imaging (MRI). Ultrasounds use sound waves to create detailed images of internal organs and can detect the presence of liquid within cysts. They help to determine the size and shape of kidney cysts and are a relatively simple way to monitor cyst growth and other changes over time. CT scans use X-rays from multiple angles to produce highly detailed layered images of the kidneys.
These scans can be used alongside ultrasounds, allowing healthcare providers to distinguish simple cysts from complex ones and kidney cysts from kidney tumors. MRIs use a powerful magnetic field and radio waves to create detailed images of the kidneys. MRIs are safer than CT scans because they don’t use ionizing radiation. However, CTs may be more advantageous for differentiating solid masses and hemorrhages.
Large, atypical, symptomatic cysts typically require regular monitoring because they can cause progressively worse symptoms and develop into severe conditions. If you have been diagnosed with a kidney cyst, it’s crucial to be extra vigilant when monitoring your symptoms and contact your healthcare provider quickly if you notice any worrisome developments.
While kidney cysts are often benign and asymptomatic, they can still present potential health risks, especially if they grow large or develop complications such as infection or rupture. It is essential to monitor any symptoms, such as backache, blood in the urine, or changes in urinary habits, which could indicate the need for medical intervention. Early diagnosis through imaging techniques like ultrasounds and CT scans helps distinguish simple cysts from complex cysts and determine the best course of action. If you experience severe or persistent symptoms, contact your healthcare provider for a check-up as soon as possible. Kidney cysts can be a scary diagnosis, but they are incredibly common and are usually completely harmless. In cases where they become problematic, there are various effective treatment options to help deal with them.
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