Many people who stay well hydrated and eat a balanced diet will not develop a kidney stone. Others who have one or more risk factors for kidney stones must actively control their diet to prevent kidney stones. In particular, people who have had a kidney stone will most likely form additional stones unless preventive measures are taken.
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Research has shown that kidney stones can be prevented by making modest changes in diet. Dietary recommendations are based on the composition and number of previous kidney stones as well as your individual health concerns; ask your doctor about diet recommendations to prevent kidney stones. Dietary guidelines that have been shown to prevent kidney stone formation include:
- Drinking more fluids. Drinking at least 10 to 14 4-ounce glasses of fluid, preferably water, per day is recommended. Fluids are crucial for people who are at risk for cystine stones. Cola beverages, coffee, and tea should be limited to two cups a day because these fluids contain oxalate, a chemical compound that naturally occurs in plants and contributes to the growth of calcium oxalate stones. More fluids may be needed to stay hydrated on hot days or when you're active. Drinking lemonade made from fresh lemons or lemon juice may help reduce the risk of kidney stone formation. Lemon juice increases the level of citrate in the urine which in turn prevents the formation of kidney stones.
- Moderating salt consumption. Sodium increases the concentrations of calcium and cystine in urine. If you have previously had a calcium or cystine stone, sodium intake should not exceed 2,000 to 3,000 milligrams a day. A tablespoon of salt contains 2,325 mg of salt.
- Eating a healthful amount of calcium. Ideally, people should eat 1,200 milligrams of calcium each day, preferably derived from food such as dairy products. A diet very high in calcium from calcium pill supplements may increase your risk of developing a kidney stone; ironically, the same is true of a diet that is too low in calcium. If calcium pill supplements are needed for prevention or treatment of bone disease, they should be taken with food to minimize the risk of kidney stone formation.
- Moderating consumption of animal protein. Consumption of animal protein should be limited to approximately 3 ounces of fish, meat, or chicken twice daily (or a total of 6 ounces daily). Eating too much animal protein can lead to elevated levels of calcium and uric acid in the urine as well as low levels of citrate in the urine, which in turn favors crystallization of calcium oxalate, phosphate and uric acid stones.
- Moderating consumption of oxalate-rich foods. Oxalate is found naturally in many fruits and vegetables. The highest amounts of oxalate are found in dark-green leafy vegetables such as kale, beet greens, okra, spinach, and swiss chard. Other plants that are rich in oxalate include instant coffee, rhubarb, starfruit, soy nuts, tofu, soy yogurt, soy milk, beets, and sweet potatoes. Limiting consumption of these foods may help prevent calcium oxalate stones from forming.
- Using vitamins carefully. Do not consume more than 100 percent of the recommended daily dose for vitamins C and D and calcium. Recent research indicates that dietary supplements, especially calcium, should be taken with a meal to minimize the risk of forming a kidney stone.
For people who continue to form kidney stones after dietary changes, doctors can prescribe medications that prevent kidney stones. Medications commonly prescribed to prevent kidney stones include:
Hydrochlorothiazides are a group of diuretics that are commonly used to prevent calcium oxalate or calcium phosphate stones. This class of diuretics decreases the amount of calcium in the urine by increasing calcium reabsorption by the kidneys. These medications are most effective in people who follow a low-sodium diet. For people taking a hydrochlorothiazide, potassium loss is a concern, and long-term monitoring of blood potassium levels is recommended. Approximately 30 percent of the people prescribed a hydrochlorothiazide need potassium supplements in their diet.
- Potassium citrate can be prescribed to boost citrate concentrations in urine. Citrate inhibits formation of calcium oxalate and calcium phosphate stones.
- Allopurinol can be prescribed to reduce the formation of uric acid in the body, which in turn can reduce the risk of uric acid and calcium oxalate stones.
- Prophylactic antibiotics can be used to prevent urinary tract infections associated with struvite stones.
- Penicillamine and/or captopril, thiola, or cuprimine can be prescribed to prevent cystine stones. However, some of these medications are not widely available, and they often are not well tolerated by the body. Therefore, their use must be closely monitored by a physician.
People with hyperparathyroidism have overactive parathyroid glands that increase the concentration of calcium in the urine, which creates favorable conditions for kidney stone formation. The parathyroid glands are located on the four corners of the thyroid gland. Hyperparathyroidism usually occurs when a small benign growth in one of these glands causes the gland to release too much calcium into the bloodstream. Occasionally, all four glands are affected simultaneously. This excess calcium is diverted into the urine, where it can crystallize as a kidney stone. In these people, parathyroid surgery may be necessary to remove the abnormal tissue in the parathyroid gland in order to prevent kidney stones and osteoporosis. This operation is performed by an endocrine surgeon, not a urologist.
Last reviewed on 10/13/09
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