Kidney cysts are small, liquid-filled sacs in the kidneys that are rather common, particularly in elderly individuals. The causes of these cysts are not known, but they may be due to calcium deposits in the kidneys or a genetic disorder. Simple kidney cysts do not cause symptoms and are benign 1. However, another type called complex kidney cysts can become calcified and lead to cancer 1. Excess cysts can cause symptoms such as back pain and high blood pressure and lead to kidney failure. Your doctor can diagnose kidney cysts with medical scans and determine the right treatment course for you.
The Kidney Cancer Institute describes a simple kidney cyst as a spherical, liquid-filled space in the kidney 1. The wall of a simple cyst is thin and without irregularities, which makes it appear distinctly on an ultrasound or scan. A simple kidney cyst does not usually cause symptoms and poses no risk of becoming cancerous 1. Simple cysts are common in individuals over the age of 50.
Complex Kidney Cyst
A complex kidney cyst is diagnosed by its irregular shape and may have thick walls 1. The Kidney Cancer Institute advises that this type of cyst is more likely to be linked to kidney cancer 1. There is a higher risk of cancer when a complex kidney cyst becomes "enhanced," or develops tissue that is vascularized 1. It may also become calcified due to calcium buildup within the cyst.
The cause of kidney cysts is not known but may be due to a buildup of calcium in the kidneys. There are several causes of excess calcium in the body, including disorders such as milk-alkali syndrome 2. The National Institutes of Health notes that this condition can be caused due to consuming excess antacid medication, such as calcium carbonate, for long periods of time. Excess vitamin D can also lead to milk-alkali syndrome 2. Other reasons for excess calcium in the body include metabolic syndromes, in which calcium is absorbed from the bones and deposited in the kidneys and other organs.
Calcium deposits in the kidneys may not cause symptoms or complications and may be reversible as long as kidney function remains intact. It is not known if calcium deposits in the kidneys lead to kidney cysts, though some cysts can become calcified. Severe cases can lead to other complications, such as calcinosis or wide-spread calcification of the kidneys and other tissues, kidney stones and kidney failure, which requires dialysis.
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