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Healthy Outlook

Drinking Water is Key to Avoiding Painful Kidney Stones

By Dr. Erica Dorfman

Monday, March 16, 2015

We know it is healthy to drink water, and that many people do not drink enough. But how much does it really matter?

Just ask anyone who ever passed a kidney stone.

Kidney stones are hard chemical deposits that can form inside kidneys, the bean-shaped organs that filter waste out of the blood and turn it into urine. They rarely grow larger than a couple millimeters, but they are extremely painful as they pass through the urinary tract and out of the body.

Nearly 9 percent of Americans have had a kidney stone, according to the National Institutes for Health, and people who get them once will probably get them again. They are a common reason for emergency hospital visits.

But we can all reduce our risk by drinking more water. We need water to live, of course, and our bodies are mostly made out of it. But water also happens to be the best way to prevent kidney stones.

Our bodies naturally create waste chemicals as byproducts of digestion, breathing and other metabolic processes. Our kidneys collect that waste, mix it with water and flush it out as urine.

The less we drink, the longer those chemicals hang around. Sometimes, when they concentrate, they form tiny solids in the kidney, often made of a calcium compound or uric acid.

A few molecules stuck together will pass unnoticed. But if a body doesn't get enough water to flush the kidneys often, that tiny solid could grow a few millimeters long.

Urine will eventually push it out of the kidney. Depending on its size, the stone will either be move slowly through the urinary tract, or it will get stuck because it's too big.

Either way, it hurts enough that someone with a stone will know that they need medical attention. Symptoms include severe pain in the belly, back or groin, blood in the urine, frequent or painful urination, and sometimes nausea.

Similar symptoms can be caused by appendicitis – which requires immediate medical attention –infection or gall bladder problems, so it's important to go to the hospital right away to find out what is wrong.

Imaging studies (such as X-rays, ultrasound or CT scans) help determine if the problem is a stone, as well as the stone's size and location in the body. Some large ones may require a procedure.

But most kidney stones are small enough to pass in a few days, anywhere from 48 hours to two weeks, and the waiting is miserable. The doctor can help manage the pain, but plenty of fluids and patience are required.

Diet and personal body chemistry can play a role in who gets kidney stones. Some people never will, but those who do so once have an increased chance of getting them again.

Cutting back on salt can help reduce the risk of forming stones, as can increasing daily intake of citric acid, found in lemons and limes. Strategies for reducing their frequency and severity should be tailored to the individual, and a urologist can help.

The most universally true way to prevent kidney stones, though, is to drink lots of water. People who have already had stones should drink between two and three liters daily.

How much water have you drunk today?

Healthy Outlook is written by the professional staff of Contra Costa Health Services, the county health department. Send questions to series coordinator Dr. David Pepper at For more health information, go to
About the Author

Dr. Dorfman is a family medicine resident at Contra Costa Regional Medical Center.