What Causes Kidney Nodules?

The cause of kidney nodules, or kidney cysts, depends on whether the cysts are simple cysts or result from polycystic kidney disease, explains Mayo Clinic. Polycystic kidney disease is an inherited condition resulting from gene mutations. The cause of simple cysts is unknown, but they appear more often in men and in people over 50 years old.

Simple cysts are noncancerous fluid-filled sacs in or on the kidneys, states Mayo Clinic. They often don't cause symptoms and doctors often discover them on an imaging test when looking for other conditions. If the patient has no symptoms, there is usually no need for treatment. If the patient experiences fever or pain, the doctor may drain the fluid of the cyst with a needle and fill the sac with alcohol, which prevents it from reforming. Large cysts may require surgery.

The cysts from polycystic kidney disease are also fluid-filled, but they grow in clusters and may get very large, according to Mayo Clinic. The disease often causes high blood pressure, loss of kidney function, pregnancy complications, brain aneurysms and chronic pain. Cysts may form on the liver, and sacs called diverticula may form inside the colon. Treatment for this disorder includes medication to manage the pain, antibiotics for infections and dialysis or a kidney transplant if the kidney fails.