What Is Kidney Cyst?

Overview

Kidney cysts are small, round, fluid-filled pouches that grow in one or both of your kidneys. There are several kinds of kidney cysts, among them simple cysts are one of the evident types. 

In most cases, kidney cysts are harmless and do not cause any symptoms at all. Since they rarely cause symptoms, many people tend to become aware of them when they undergo an imaging test for other reasons.

However, some kidney cysts may require treatment if they begin to exhibit symptoms. To determine the cause and administer the appropriate treatment, your doctor might suggest diagnostic testing.

Kidneys are the bean-shaped organs that are responsible for filtering waste out of your blood circulation and making urine. Within the kidneys are the tiny working parts called nephrons which typically help in filtering and removing the extra products to leave through urination. You might have single or multiple cysts on either one or both of your kidneys.

Many individuals often relate simple renal cysts to polycystic kidney disease (PKD), which is not the case in reality. Simple kidney cysts are small, thin-walled pouches that contain water-like fluid. They neither impair kidney function nor damage them. Simple kidney cysts also differ from complex cysts. In comparison, polycystic kidney disease is an inherited condition that causes several numbers of cysts to form in your kidneys, which can become enlarged and later affect the kidney's performance.

Simple cysts can vary in size from being so small that they can only be seen under a microscope to as large as a golf ball.

Although rare, if cysts begin to increase in size, they can press on nearby organs, resulting in pain and other symptoms.

Causes of kidney cysts

A kidney cyst may start to grow in the tube of the nephron when it is blocked, swollen up, or filled with fluid. It is still not fully known what causes renal cysts to occur. However, many researchers do have a few possible explanations.

Unlike cystic kidney diseases, simple cysts are not inherited; it is also believed that they might develop due to microscopic blockage or injury.

Moreover, kidney cysts are likely to develop in older adults. In fact, they are known to be more prevalent in people who are older than 50 years of age.¹ One study indicated that kidney cysts are more common in men than in women.²

Along with advancing age and male gender, studies have strongly linked blood pressure, smoking, and renal dysfunction as possible causes of renal cysts.³  Several studies have also indicated Type-2 Diabetes Mellitus as an associated risk factor for renal cysts. However,  the relationship between these two conditions is still debatable.⁴

Signs and symptoms of kidney cysts

Typically, kidney cysts do not cause any symptoms and often go unnoticed. In fact, many individuals only find out about their cysts when issues like bleeding, rupture, overgrowth, or infection take place.

However, common  signs and symptoms may include:

• Fever
• Frequent urge to urinate
• Upper abdominal pain
• Dull pain in between the ribs and pelvis region
• Hematuria - blood in the urine
• Dark urine

Depending on the size and location of the cyst, it may impair the kidney's capacity to filter out the extra fluid from the blood, which in certain cases leads to high blood pressure.

Management and treatment for kidney cysts

Generally, kidney cysts do not require treatment unless they begin to exert pressure on the nearby organs, become painful, or affect kidney function. If any of these complications happen, then your doctor might perform certain procedures to either shrink or remove the troubling cyst. The most common treatments to manage kidney cysts include:

Sclerotherapy and aspiration:

 In this procedure, a doctor uses a long needle through the skin to puncture the cyst and drain (aspirate) its fluid content. They may fill the pouch again with a strong solution to shrink the tissues. This lowers the chances of cysts coming back.

Surgery: 

Doctors might perform surgery if the cysts reoccur or are large enough to affect renal function. Surgeons often perform laparoscopic surgery using tiny instruments and through several small incisions in the abdomen. During surgery, doctors first aspirate the cysts and then cut or burn the walls of the cyst. If you have this surgery, then you might need to stay in the hospital for a few days.

FAQs

Are kidney cysts common

Kidney cysts are very common, particularly among people of older age. Most people might have a single cyst on their kidney, but the likelihood  of multiple cysts and the risk of them growing on the second kidney increases with age.

Who are at risk of kidney cysts

Older adults, early kidney dysfunction, hypertension, and people who smoke are more at risk of developing kidney cysts than others. Moreover, men are at greater risk of kidney cysts in comparison to women.

How are kidney cysts diagnosed

For diagnosing a kidney cyst, a medical specialist called a urologist may take your blood or urine sample to check the kidney's functions. They might also perform any of the following imaging tests to monitor cysts and rule out health complications (for example, kidney cancer, complex renal cysts, or chronic kidney diseases).

• A computed tomography (CT) scan uses powerful X-rays and 3D imaging scans to evaluate the fluid-filled cysts in the kidneys
• Magnetic resonance imaging (MRI) is an imaging technique that utilises magnetic, radio waves and a computer to take different images of the body to identify cysts from solid masses
• The ultrasound technique uses sound waves to generate images and helps doctors determine the size of the cysts

How can I prevent kidney cysts

Unfortunately, you cannot prevent kidney cysts. However, you can reduce the chances of getting them by drinking plenty of water and minimising sodium intake if you are older than 50, have high blood pressure, or have a history of kidney disease.

When should I call my doctor

Although kidney cysts are harmless, it is advised to consult your doctor if you experience:

• Pain in the upper abdomen, hips, or back
• Frequent urge to urinate
• Fever
• Dark urine or blood in the urine

Experiencing any of the symptoms above means that the cyst might have become infected, enlarged, or ruptured.

Summary

Kidney or renal cysts are tiny, thin-walled pouches containing watery fluid that grow in one or both of the kidneys. Kidney cysts are common and typically do not cause any symptoms or affect the kidney's function.

In most cases, they are often found during imaging tests for other health reasons. The exact cause of kidney cysts is still not fully understood, but they are highly associated with progressing age, male gender, renal dysfunction, and people who have high blood pressure.

In some cases, kidney cysts can become large or increase in number enough to cause symptoms.

It is recommended to talk with your doctor if you experience any mentioned symptoms. Your doctor may perform a series of diagnostic and imaging tests to evaluate the functions of your kidneys and to rule out other possible complications.