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Topic Overview
What are kidney stones?
Kidney stones (renal calculi or nephrolithiasis) are made of salts, minerals, and other substances normally found in the urine that stick together and build up on the inner surfaces of the urinary system. Stones can develop in the kidney, the ureter, or the bladder. About 80% of kidney stones contain calcium compounds, mostly calcium oxalate, and are called calcium stones.
What causes kidney stones?
Urine is made up of a normal chemical balance of water, salts, minerals, and other substances. Factors that affect the normal balance of the urine can lead to kidney stone formation. The most common cause of kidney stones is decreased fluid intake (dehydration). When you become dehydrated, the salts, minerals, and other substances in the urine are more likely to stick together and form a stone.
Certain medical conditions can also change the balance of minerals in your urine and lead to stone formation.
What are the symptoms of kidney stones?
Kidney stones can be as small as grains of sand or as large as golf balls. They are often painless in the kidney but may cause sudden, severe pain as they travel from the kidneys to the bladder. Stones can block the flow of urine or cause bleeding so the urine looks pink or red. Nausea and vomiting may also be present.
Who develops kidney stones?
Kidney stones affect:
- About 2 out of every 1,000 Americans each year. People are usually between 20 and 40 years old when they develop their first kidney stone.
- About 12% of Americans sometime during their lives.
- Men three times more often than women.
- White people more often than African-Americans or Asians.
- Families. About 25% of people with kidney stones have a family history of the condition.
- People living in mountainous, desert, or tropical areas more often than those in other geographic areas.
- People more often in the summer months than other seasons of the year.
People who have an inactive (sedentary) lifestyle. - Almost half of all people who develop kidney stones will develop more stones within 5 to 10 years unless preventive measures are taken.
How are kidney stones diagnosed?
A kidney stone is usually diagnosed by the presence of pain in the kidney area and other urinary symptoms, followed by tests to view the kidneys and the urinary system.
Tests to determine the cause of the stone may be done the first time you have a kidney stone to help determine whether the normal chemical balance of water, salts, minerals, and other substances in your urine has changed. If you continue to develop stones, more extensive testing will be done to determine the ongoing cause.
How are kidney stones treated?
If a stone is small enough to pass on its own, treatment usually includes increasing your fluid intake to flush the kidneys and taking medication to control pain. If a stone is too large to pass on its own, or gets stuck in the urinary tract, a medical procedure may be needed to break up the stone into smaller pieces that will pass in the urine.
