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Take steps to prevent kidney stones

Q. My family has a history of kidney stones, and I’d like to prevent them if possible. What should I do to keep from getting kidney stones? Are there foods or drinks I should avoid?

A. A family history of kidney stones does increase your risk of developing them. But you can take a number of steps to help prevent kidney stones from forming. One of the most important is to drink plenty of fluids each day. Making certain dietary choices and staying at a healthy weight also can lower your risk.

Your kidneys filter waste and excess fluid from your blood. That waste and fluid leave your body through urine. Kidney stones form when urine contains more crystal-forming substances – such as calcium, oxalate and uric acid – than the fluid in your urine can dilute. At the same time, due to your genetics or other factors, your urine may not have substances that keep crystals from sticking together. That creates an ideal environment for kidney stones to form.

For people with family members who have had kidney stones, the risk of stones is about twice as high as for people without a family history. Other factors that can raise your risk include surgeries that change your digestive process, such as gastric bypass, and diseases that affect your digestion, such as inflammatory bowel disease or chronic diarrhea.

People who live in warmer climates tend to have more kidney stones than those in colder climates. That seems to be related to the increased amount of time they spend outdoors in warm weather and, as a result, the amount they sweat. Sweating can lead to dehydration, and that is a significant risk factor for kidney stones.

Because dehydration is one of the leading causes of kidney stones, drinking enough liquid every day is key to preventing stone formation. When you make about 2½ liters of urine a day, you’re getting the right amount of liquid. Of course, the amount of urine you produce can be hard to measure. A rule of thumb is that your urine should look almost clear. If it is dark, it’s more concentrated, and stones are more likely.

Your best beverage choice is water. To increase the benefit, add lemon to it, as citric acid has a protective effect against kidney stones. Sugar-free lemonade and diet citrus-based sodas also are good choices. Avoid dark sodas. They contain phosphoric acid. That may raise the risk of kidney stones. Also, your beverages should be low in sugar or sugar-free, since sweet drinks and foods raise your risk of other conditions, such as obesity and diabetes.

Some people advocate drinking cranberry juice to prevent stones. However, research has not shown a beneficial effect. One study even demonstrated that cranberry juice raises the risk of kidney stone formation. But as a rule, if you like cranberry juice, it’s fine to drink it in your effort to get plenty of liquids.

Diet plays a role in the likelihood of kidney stones. Eating a diet high in protein, sodium and sugar may raise the risk of kidney stone formation in some people. With that in mind, strive for a diet low in salt and sugar. Limit protein that comes from animal sources. Instead, try to choose plant-based protein sources, such as beans, peanuts, lentils and peas.

If you are overweight, the way your body absorbs some substances, including oxalate, can be affected. So getting to a healthy weight may also help lower your risk of getting kidney stones. Consider having a discussion with your health care provider to review of your family and health histories, as well as a talk about possible lifestyle changes.

Dr. Amy Krambeck is a urologist at the Mayo Clinic in Rochester, Minn. See related story, Pages 8-9