Kidney Stones

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Kidney Stones

Anyone who has passed a kidney stone can verify that this is an experience he never wants to repeat.

The stone has to travel down a passage--the ureter--that easily carries liquid but has a terrible time with a small, grainy, calcified object like a kidney stone.

When it's all over, the stone passer (who is most often male) will breathe a huge, well-deserved sigh of relief. The trouble is, relief may last only for a while.

Usually, once you've had one stone, you're at a higher risk of getting another, says Leroy Nyberg, M.D., director of the urology program at the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health in Bethesda, Maryland. And then the risk can double after a second stone.

What causes these pebbles of pain? When the concentration of stone-forming minerals such as calcium or oxalate in your urine is too high, you begin to get a buildup of crystals of calcium salts and other minerals that are normally flushed away during urination. The buildup of these crystals in the kidneys eventually begins to form into a hard deposit, similar to a rough pebble. Besides the pain stones cause, you may detect blood in the urine. Only time--and a heck of a lot of water--will help flush a kidney stone. Sometimes a stone must be surgically removed.

Your doctor will need to determine by chemical analysis what kind of kidney stones you have and which treatments are appropriate. But here are some ways you can reduce your chances of forming another pain-producing stone.

Drink a lot of water. By increasing fluid intake, you raise urine volume and decrease the concentration of stone-forming elements in the urine. But how much is enough? "I tell my patients to drink enough fluid that they have a urine volume at least equivalent to a two-liter soft-drink bottle every day," says Brad Rovin, M.D., a kidney specialist and assistant professor of medicine and nephrology at Ohio State University College of Medicine in Columbus. To do that, you may have to drink almost a gallon of water a day--especially if you spend a lot of time exercising outdoors.

"It's even more important for people with stones, or who are prone to them, to keep properly hydrated," says Dr. Rovin. And it is important to gauge your urine output. Dr. Rovin suggests using an empty milk carton for measuring, until you find out how much you have to drink to get at least two liters' worth of urine.

When to See the Doctor Once you pass a stone (thank goodness!), your doctor needs to evaluate it, so you can take measures to reduce your risk of developing another. You should also see your doctor if you're experiencing pain in the groin, lower back or testicles or if you see blood in the urine. Any of these signs may indicate that you're getting another stone.

Get plenty of exercise. Regular exercise helps put calcium back into your bones, where it's most needed. "People who are inactive tend to accumulate calcium in the bloodstream," says Dr. Nyberg. A daily workout for at least 30 continuous minutes is advised.

Watch your calcium. Most stones are calcium-based, so it's essential that you avoid excessive intake of milk, butter, cheese and other calcium-rich dairy foods. "If you've had a kidney stone, you shouldn't have more than one gram of calcium a day--the equivalent of about three glasses of skim milk," says Dr. Rovin.

Monitor protein. But calcium isn't the only no-no. Protein can also raise calcium levels, and it may increase the presence of uric acid and phosphorus in the urine--which may lead to stone formation. So if you've had uric acid or cystine stones, don't exceed six ounces of meat, fish or other protein-rich foods daily.

Bypass oxalates. If you've had a calcium oxalate stone (your doctor can tell you), then oxalate-rich foods can cause you trouble. So limit your intake of beans, beets, blueberries, celery, chocolate, grapes, nuts, rhubarb and spinach.

Contain condiment consumption. Table salt and condiments high in sodium should also be avoided. Salt restriction will help decrease the concentration of calcium in the urine. You should reduce your sodium intake to two to three grams per day, according to the National Kidney Foundation. Besides limiting high-salt seasonings such as ketchup and mustard, reduce consumption of processed and pickled foods, luncheon meats and snack foods such as chips and pretzels.

Beware of stomach antacids. Some antacids are enormously high in calcium, warns Peter D. Fugelso, M.D., medical director of the Kidney Stone Department at the Hospital of the Good Samaritan and clinical professor of urology at the University of Southern California, both in Los Angeles. If you've had a calcium stone, and if you are taking an antacid, check the ingredients listed on the side of the box, and make sure the antacid is not calcium-based. If it is, choose another brand.

Be a careful vitamin shopper. Ask your doctor about using certain vitamins to prevent future stones. A daily supplement of magnesium helped stop stone recurrence in nearly all those included in one Swedish study--so it's a good bet that magnesium supplements are beneficial. Also, vitamin B₆ is believed to lower the amount of oxalate in the urine. (But your doctor will probably tell you to avoid supplements that also contain vitamins C and D, since these nutrients increase the risk of calcium-based stones.)