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Preventing and Treating Kidney Stones

Kidney Stone

Kidney stones are notorious for being painful. The feeling has been described as being worse than childbirth labor pains. More than a million kidney stones are diagnosed in the United States each year. About 1 in 10 Americans will suffer from a kidney stone at some point.

Kim Sebaly, a 74-year-old retired university professor, lived with kidney stones for almost 25 years before he needed surgery to remove them. After undergoing four surgeries to remove kidney stones last year, he is now very careful about what he eats and drinks. He says he wishes he knew years ago about how he could have changed his diet to reduce his risk of stone formation. "I am much better educated today about how to lower my risk of kidney stones," says Kim. "I drink a lot of fluids and have cut down on my use of salt. Kidney stones have made me a much more intelligent consumer of food."

In 1989, Kim had kidney stones on his left side that were broken up through shock wave lithotripsy, the most commonly used procedure for removing kidney stones. Shock wave treatment is non-invasive and uses a machine called a lithotripter. It creates shock waves that pass through skin and tissue until they hit the dense kidney stones. The impact causes stress on the stone. Repeated shock waves cause more stress, until the stone eventually crumbles into small pieces. These sand-like particles are easily passed through the urinary tract in the urine.

In 2007, Kim developed painful kidney stones on the right side, which required further treatment. Last year, he underwent a surgical procedure called percutaneous nephrolithotomy (PNL), which requires small incisions about the width of a paper clip.

How do kidney stones develop? Normally, urine contains many dissolved substances. At times, some materials may become concentrated in the urine and form solid crystals. These crystals can lead to the development of stones when materials continue to build up around them. Stones formed in the kidney are called kidney stones. A ureteral stone is a kidney stone that has left the kidney and moved down into the ureter, the tubes that carry urine from the kidneys to the bladder.

The majority of stones contain calcium, with most of it comprised of a material called calcium oxalate.

Once stones form in the urinary tract, they often grow with time and may change location within the kidney. Some stones may be washed out of the kidney by urine flow and end up trapped within the ureter or pass completely out of the urinary tract. Stones usually begin causing symptoms when they block the outflow of the urine from the kidney leading to the bladder because the blockage causes the kidney to stretch.

The pain often begins suddenly as the stone moves in the urinary tract, causing irritation and blockage. Usually a person feels a sharp, cramping pain in the back and in the side of the area of the kidney or in the lower abdomen, which may spread to the groin.

Sometimes a person will complain of blood in the urine, nausea or vomiting. Occasionally stones do not produce any symptoms. But these “silent” stones can still grow and, in rare cases, can cause irreversible damage to kidney function. More commonly, however, if a stone is not large enough to cause major symptoms, it still can trigger a dull ache that is often confused with muscle or intestinal pain. Fortunately, most stones pass out of the body without any intervention.

Half of people who have formed a stone will develop another stone. That’s why it is so important for patients to follow their doctors’ advice to drink plenty of fluids to reduce their risk, according to Dr. Manoj Monga, co-author of the new American Urological Association guidelines on the medical management of kidney stones. “We tell patients who have had kidney stones to drink 10 10-ounce glasses per day of any liquid except for dark colas,” explained Dr. Monga, Professor of Surgery/Urology and Director of the Stevan Streem Center of Endourology and Stone Disease at the Cleveland Clinic. When a person doesn’t drink enough fluids during the day, the urine can become concentrated and darker. This increases the chance for crystals to form within the urine as there is less fluid available to dissolve them.

“It can take a while to get used to drinking so much,” said Dr. Monga. “Most patients find they need to force themselves at first.”

Kim says, “I now drink water morning, noon and night.”

Dr. Monga also tells patients to limit sodium to no more than 1,500 milligrams a day. An increased amount of sodium passing into the urine can also pull calcium into the urine. Increased calcium in the urine increases the chance that stones will form. People who have had stones should also eat foods rich in citrate, which helps block stones from forming. Citrate is found in lemons, limes, oranges and melons. Two fresh lemons or limes, or four ounces of lemon or lime concentrate is recommended daily.

"There is a misconception that you should limit the amount of calcium you consume if you have had kidney stones," observes Dr. Monga. "In fact, even though calcium in the urine increases the risk of stone formation, calcium in your diet can protect against stone formation. You should have about three- to-four servings of calcium-rich products a day."

Kim’s stones had a high amount of calcium oxalate. “If you have had oxalate stones, you need to learn which foods have high, medium and low oxalate content,” he says. Oxalate-rich foods include leafy green vegetables, nuts, tea or chocolate.

Doctors usually advise their patients to start with changes to their diets to see if they can avoid future kidney stones. Stone disease has been linked with obesity, and some studies suggest physical activity can actually protect against stones. In some cases, medication is also needed to prevent stone formation.

If you have had kidney stones, your doctor may ask you to have a 24-hour urine stone risk test, repeated every three-to-six months until the doctor decides your risk for more stones is reduced. At that point, you may have to repeat the test every year or two. During the test, your urine is collected for a full day and analyzed for substances that may increase or decrease your risk of stone formation.

Doctors may order an X-ray or sonogram to diagnose a kidney stone and to see the stone’s size and location. In some cases, a doctor will scan the urinary system with computed tomography (CT) to look for stones.

The size, number and location of the stones will help the doctor decide the best treatment. In general, you are likely to need surgery if your stones are large enough to block urine flow, if they are potentially harmful to your kidneys or if they are causing symptoms for which medication does not help.

In addition to shock wave lithotripsy, the other two common treatment options are ureteroscopy and PNL (the surgery Kim had last year).

Ureteroscopy involves the use of a very thin, fiber-optic instrument called a ureteroscope, which allows access to stones in the ureter or kidney. The urologist inserts the ureteroscope into the person’s ureter via the bladder. No incisions are necessary. Once the urologist sees the stone through the ureteroscope, a small, basket-like device can be used to grasp smaller stones and remove them. If a stone is too large to remove in one piece, it can be broken with a laser into smaller pieces that can then pass with urine.

PNL is the treatment of choice for large stones located within the kidney that cannot be treated with either lithotripsy or ureteroscopy. The urologist makes a small incision, then places a needle through the incision. A wire is inserted into the kidney and directed down the ureter. A passage is then created around the wire using dilators to provide access into the kidney. A larger telescope called a nephroscope is then passed into the kidney to see the stone. The doctor uses other instruments to break up the stones.

Open surgery, in which a large incision is made to remove the stone, is used only in extremely rare situations and for very complicated cases of stone disease.

“Once a person has kidney stones, they are usually very motivated to make changes because they never want to experience that level of pain again,” said Dr. Monga. “Most of the changes we recommend include drinking plenty of fluids, cutting out salt, getting enough calcium, and exercising. What’s good for your overall health is good for your kidneys.”

Half of people who have formed a stone will develop another stone. Here are some tips to prevent stones from recurring:

  • Exercise regularly.
  • Drink 10 10-ounce glasses per day of any liquid except for dark colas.
  • Limit sodium to no more than 1,500 mg a day.
  • Eat two fresh lemons or limes or 4 oz. of lemon or lime concentrate daily.
  • Eat three-to-four servings of calcium-rich foods per day.
  • Based on the kind of stones you have formed, your urologist may have more advice on what you should and shouldn’t eat.
“It can take a while to get used to drinking so much,” said Dr. Monga. “Most patients find they need to force themselves at first.”

Kim says, “I now drink water morning, noon and night.”

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