November 8, 2013
Dear Mayo Clinic:
I continue to get kidney stones despite drinking plenty of water. They are quite small and I haven't had to be treated yet. But my doctor said if my symptoms get worse, I will need treatment. What would that involve?
Treatment for kidney stones depends on the type of stone and their cause. In many cases, dietary changes and medication are all that's needed for small stones. Larger stones may require additional treatment.
Kidney stones form from minerals and acid salts. About 85 percent of kidney stones are calcium based, typically calcium oxalate. Less common are uric acid stones, struvite stones and cystine stones. Your doctor can use blood and urine tests to find out what kind of stones you have. If you have passed a stone, a laboratory analysis can reveal the make-up of the stone.
If your stones are calcium oxalate — as most kidney stones are — you need to keep doing what you have already started: drink lots of water. The typical recommendation is to drink about 8 to 10 ounces of water every hour you are awake.
There are several benefits to drinking that much water when dealing with kidney stones. First, it flushes out your urinary system and helps small stones pass more easily. Second, diluted urine lowers the chances that calcium oxalate stones will form in the first place. Drinking plenty of water can help prevent uric acid stones and cystine stones, too.
A variety of changes in your diet can lower your risk of forming new calcium oxalate stones. Oxalate is a substance found in certain foods. For people at risk for these kidney stones, eating fewer oxalate-rich foods can help. They include foods such as spinach, beets, Swiss chard, rhubarb, almonds and granola, among others.
A low-salt diet can be useful in preventing calcium oxalate kidney stones, as can getting the right amount of calcium from the foods you eat. Some people with kidney stones are advised to eat more citrus fruits because a substance in those fruits, called citrate, can naturally inhibit stone formation.
For uric acid stones, cutting back on the amount of protein you eat — especially protein from animal sources — may help prevent new stones.
Ask your doctor to recommend a dietitian you can talk with about a diet that is right for you. He or she can review food choices that may lower your risk of new kidney stones and help you plan some sample menus to get started.
In some cases, medication also can treat kidney stones and prevent new ones from forming. Again, the specific medicine you need depends on the type of stone you have. Doctors often prescribe a thiazide diuretic — a water pill — for people with calcium stones. In addition, a citrate supplement may be appropriate for people with very low levels of citrate in their bodies.
Medications can help lower the amount of uric acid in the blood and urine for people who tend to form those types of stones. Struvite stones are associated with infections. In some cases, long-term use of antibiotics in small doses may help keep urine free of bacteria that can cause infection. Medicines can sometimes be used to lower the amount of cystine in the urine for people who have cystine stones.
If you develop larger kidney stones, you may need more invasive treatment. Procedures are available to break up large kidney stones into small pieces that can pass through your urinary tract. For very large stones, surgery is sometimes necessary to remove them.
Right now, the best step is to talk with your doctor about tests that can show what type of kidney stones you have. Once you know that, you can make a plan to help prevent and treat new stones.
— Vincent Canzanello, M.D., Nephrology, Mayo Clinic, Rochester, Minn.