October 1, 2010
Dear Mayo Clinic:
Are kidney stones genetic? I have only had them once, but my dad had stones several times. I'm hoping I won't follow that path. Any advice for prevention?
Heredity does play a role in the formation of kidney stones, and after you've developed them once, you are at an increased risk of 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 percent of the United States population experience recurrent 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 (a mineral found in some fruits and vegetables, as well as in nuts and chocolate) are also at higher risk of kidney stones. Normal intake of calcium in the diet may help prevent stones, while excessive amounts of calcium 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 percent 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 doctor to establish an individual treatment plan that fits your situation. That plan should take into consideration what kind of kidney stones you have, possible causes for their formation, and specific steps to prevent them.
There are several types of kidney stones. The most common are calcium-based stones: calcium oxalate or calcium phosphate. They make up about 75 percent of kidney stones. Others include uric acid stones, struvite stones (which form in response to an infection) and cystine stones, as well as a variety of other rare types of kidney stones. Determining the type of stones you have is key to preventing them from forming in the future.
After a passed stone has been captured, its makeup can usually be established through laboratory analysis. Because each type of stone forms for different reasons, blood and urine tests can also help determine what's causing stone formation. For example, blood tests may reveal excess calcium or uric acid in your blood. Urine tests may 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 doctor can work with you to develop a plan to prevent future stones. Prevention typically involves dietary changes, adjustments in fluid intake and, in some cases, medications.
By carefully following an individualized treatment plan, more than 90 percent 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 doctor about prevention strategies that are right for you.
— William Haley, M.D., Nephrology, and Michael Wehle, M.D., Urology, Mayo Clinic, Jacksonville, Fla.