What Are Kidney Stones?

Diagram of Kidney with Kidney Stones

A kidney stone, also called nephrolithiasis, is a small, hard mineral and uric acid salt deposit that forms inside your kidneys and may affect any part of your urinary tract.

When passed, kidney stones can cause severe pain. Most kidney stones may be treated without surgery, but in cases of persistent pain or infection, it may be necessary to remove the urinary obstruction.

There are five main types of kidney stones:

  • Calcium stones (calculus disease), which can be caused an excess of oxalate-containing foods, high doses of vitamin D and certain metabolic disorders. More than three-quarters of all kidney stones are calcium-based.
  • Uric acid stones, which can be associated with dehydration, a high-protein diet and gout
  • Struvite stones, which can be caused by a urinary tract infection
  • Cystine stones, which is caused by cystinuria, the excess excretion of amino acids
  • Xanthine stones, which are very rare

Who is affected by kidney stones?

Kidney stones are one of the most painful disorders, and one of the most common disorders of the urinary tract. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) estimates that about one million people in the United States are treated for kidney stones each year. Consider these NIDDK statistics:

  • Caucasians are more prone to kidney stones than African-Americans.
  • Although stones occur more frequently in men, the number of women who develop kidney stones has been increasing.
  • Kidney stones most often strike people between age 20 and 40.
  • Once a person develops more than one stone, he or she is more likely to develop additional stones.

Related Resources

  • Cystoscopy: A cystoscopy is done using a telescope-like instrument called a cystoscope.

  • Intravenous Pyelogram (IVP): An IVP is an X-ray test that uses a contrast agent to show the urinary system.