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DEAR MAYO CLINIC: My father has had dozens of kidney stones in recent years. I have had a kidney stone once. Are kidney stones genetic? I'm wondering if I will follow in his path and if there is anything I can do to prevent kidney stones.
ANSWER: Heredity plays a role in the formation of kidney stones, and after you've developed them once, you are at an increased risk of additional kidney stone formation in the future. Fortunately, effective strategies are available to prevent kidney stones.
Kidney stones are small, hard deposits made of minerals and acid salts that form inside the kidneys. Although the stones start in the kidneys, most people don't know they have kidney stones until the stones move into the ureter — one of two tubes connecting the kidneys and bladder. Stones often become wedged in the ureter or in the opening of the kidney that leads to the ureter, causing urine to back up and resulting in severe pain.
Kidney stones are common. About 12% of the U.S. population has experienced repeated bouts of these stones. If you have a family member who has had kidney stones, then you're more likely to develop kidney stones. But other factors can affect your risk, too.
For example, although the reason isn't clear, people who live in warm Southern climates near large bodies of water have a higher incidence of kidney stones than people who live in the Midwest. People who eat a diet that's high in protein or salt, or has excessive amounts of oxalate, are also at higher risk of kidney stones. Oxalate is a mineral found in many fruits and vegetables, as well as nuts and chocolate. Normal intake of calcium in the diet may help prevent stones, while excessive amounts of calcium or the use of calcium supplements may promote stone formation.
Kidney stone development often begins during a person's 20s or 30s, and the problem may continue for many years. Nearly 80% of people who have had kidney stones once will develop them again if preventive steps aren't taken. Because the reason for kidney stone formation is specific to each person, it's important to work with your health care provider to establish an individual treatment plan that fits your situation. That plan should consider what kind of kidney stones you have, possible causes for their formation and specific steps to prevent them.
Of the several types of kidney stones, the most common type is calcium-based stones: calcium oxalate or calcium phosphate. They make up over 75% of kidney stones. Others include uric acid stones, struvite stones that form in response to an infection and cystine stones, in addition to a variety of other rare types of kidney stones. Determining the type of kidney stones you have is key to preventing them from forming in the future.
After a passed stone has been captured, its makeup usually can be established through laboratory analysis. Because each type of stone forms for different reasons, blood and urine tests also can help determine what's causing stone formation. For example, blood tests can reveal excess calcium or uric acid in your blood. Urine tests can show that you're producing too many stone-forming minerals or too few stone-inhibiting substances.
Once the type of stone and its cause have been established, your health care provider can work with you to develop a plan to prevent future stones. Prevention typically involves adjustments in fluid intake, dietary changes and in some cases medications.
By carefully following an individualized treatment plan, more than 90% of people can successfully prevent additional kidney stones. This is true even if you have a genetic predisposition to kidney stone development. If you haven't already done so, talk with your health care provider about prevention strategies that are right for you. — Dr. Ivan Porter II, Nephrology, Mayo Clinic, Jacksonville, Florida