Kidney cysts are round pouches filled with fluid which form on or in the kidneys. They can be associated with serious disorders which can impair the kidney function. In the most cases, kidney cysts are a type called simple kidney cysts that are noncancerous cysts which in rare cases cause complications. It is not known what the cause for simple kidney cysts is. Usually, only one cyst happens on the surface of a kidney, but multiple cysts can affect one or both kidneys. You should know that simple cysts are not the same as the cysts which form with polycystic kidney disease.
Simple kidney cysts are often detected during an imaging test which is made for another condition. Simple kidney cysts do not cause signs and symptoms and they usually do not need treatment. Some kidney cysts are so small and they cannot be seen without a microscope. Other kidney cysts can grow large as tennis ball. As these cysts are getting larger, they can press on nearby organs and cause pain. In the most cases, kidney cysts are harmless and they do not cause problems. 
If the cyst grows, then surgery or sclerotherapy can remove it without a long – term complications. If you have polycystic kidney disease, then you should know that it can be serious. If this disease is not treated, then it can cause complications, such as kidney failure and high blood pressure.
Kidney cysts symptoms
Simple kidney cysts usually do not cause signs or symptoms. If the simple kidney cyst grows enough large, then the symptoms can include:
- Upper abdominal pain
- Urinating more often than usual
- Blood in the urine
- Dull pain in your back or side between the ribs and pelvis (the pain is usually dull, but it can become severe if the cyst bursts)
- Dark urine
- Swelling of the abdomen
PKD can cause signs and symptoms, including
- Blood in the urine
- High blood pressure
- Pain in the back and side
You should talk with your doctor if you have some of the mentioned signs and symptoms of kidney cyst. You might see a specialist called urologist to diagnose the kidney cyst. Your doctor may take a blood or urine sample to see how well your kidneys are working. Your doctor may perform some of the next imaging tests: computer tomography scan, magnetic resonance imaging or ultrasound. If the cyst is small and it does not cause any problems with your kidneys, then you may not need to treat it.
You may just have imaging tests done every six to twelve months to make sure that the cyst has not grown. If you have larger kidney cysts or cysts which cause symptoms, then the treatments of it include surgery and sclerotherapy. You should tell your doctor what kind of symptoms you feel or if you have used some natural remedies or medicines to treat it, so he can give you the right diagnosis and treatment.
Kidney cysts causes
It is not known what the cause for kidney cyst is. In one theory is said that kidney cysts develop when the surface layer of the kidney weakens and it forms a pouch (diverticulum). Then, the pouch fills with fluid, detaches and develops into a cyst. It is noticed that you are having more chances of getting kidney cyst as you are getting older. It is noticed that by age of 40, about 25% of people will have them.
By age of 50, about 50% of people will have kidney cysts . Also, men have more chances of having kidney stones compared to women. PKD is an inherited condition and this means that it is caused by changes to genes which are passed down through families.
As you are getting older, your risk of having kidney cyst is increasing, but they can happen at any age. It is noticed that simple kidney cysts are more common in men. 
Kidney cysts can occasionally lead to complications, such as
- Urine obstruction: The kidney cyst which obstructs the normal flow of urine can lead to swelling of the kidney (known as hydronephrosis). 
- A burst cyst: The kidney cyst which bursts cause severe pain in your back or side.
- An infected cyst: The kidney cyst can become infected which is causing pain and fever. 
 Gimpel C, Avni F, Breysem L, et al. Imaging of kidney cysts and cystic kidney diseases in children: An International Working Group consensus statement. Radiology. 2019;290(3).
 Marumo K, Horiguchi Y, Nakagawa K, et al. Incidence and growth pattern of simple cysts of the kidney in patients with asymptomatic microscopic hematuria. International Journal of Urology. 2003;10:63–7
 National Institute of Diabetes and Digestive and Kidney Diseases. Simple kidney cysts. Retrieved from www.niddk.nih.gov/health-information/kidney-disease/simple-kidney-cysts
 Lantinga MA, Castelejin NF, Geudens A, et al. Management of renal cyst infection in patients with autosomal dominant polycystic kidney disease: a systematic review. Nephrology Dialysis Transplantation. 2017;32(1):144-50.
 Dharnidharka VR. Infected kidney cysts. Nephrology Image. 2006;69(5):783.