Kidney stones are solid, stone-like lumps that form within the kidneys. They can be as small as a grain of sand or as large as the size of a golf ball (sometimes even larger). Most stones are less than a third of an inch in diameter.
The stones are actually accumulations of mineral salts and other substances. Similar stones also can form in most other portions of theurinary tract.
Many of these stones are small enough to pass out of the body during urination, but some larger stones may partially or fully block the normal flow of urine. Kidney stones can cause intense pain and other symptoms.
About 10 percent of people will experience a kidney stone at some time during life. Kidney stones are a common cause of blockage of the urinary tract in adults, accounting for 1 of every 1,000 hospitalizations.
What Are Kidney Stones Made Of?
Kidney stones consist of:
A center that consists of crystal-like substances
A surrounding region that is composed of layers
Kidney stones are composed of different chemical substances. Each of the major types is named for its main chemical ingredient. They are: