Want to Reduce Your Risk of Kidney Stones?

Whether they are as small as a grain of sand or as large as a golf ball, kidney stones can be extremely painful. Fortunately, there are ways to prevent developing kidney stones or at least minimize their size and impact, says UNC Health urologist David F. Friedlander, MD, MPH.

“Across the country, about 10 percent of people will suffer from kidney stones in their lifetime,” he says. “In the Southeast—the ‘stone belt’—the incidence is even higher.”

Our kidneys filter minerals and other waste out of our blood that our bodies haven’t absorbed, Dr. Friedlander says. Most of these substances pass right out of our bodies in our urine.

“But if the urine is more concentrated (more substances and less water), then the minerals are more likely to form a kidney stone,” he says.

Causes of Kidney Stones

Kidney stones form when substances in the urine harden into crystals. The most common type of stone is made of calcium oxalate. Others are uric acid, struvite and cystine.

Calcium oxalate stones form when calcium and oxalic acid combine. Not getting enough calcium or drinking enough fluids can contribute to their formation. So can eating foods high in oxalates.

“The foods that are notorious for high levels of oxalates are spinach, peanuts, potatoes and chocolate,” Dr. Friedlander says. “Certain types of tea have high levels of oxalate, especially black and green teas. Sweet tea has very high levels of oxalate.”

Table sugar, such as what’s commonly added to sweet tea in the “stone belt,” also can increase the risk of developing kidney stones.

Lowering your intake of oxalates may help reduce your risk. You probably don’t need to decrease the amount of calcium you’re consuming, though—if calcium is plentiful, it may combine with oxalate before it gets into the kidneys, helping both to leave the body without forming a stone.

“It’s like Goldilocks,” Dr. Friedlander says of calcium intake. “You don’t want too much or too little, but just right.”

Risk Factors for Kidney Stones

Because people in the Southeast develop kidney stones twice as often as those in the rest of the country, they may want to pay particular attention to their diet and fluid intake, Dr. Friedlander says.

“The greater humidity and heat during the summer months may cause people to sweat more and become more dehydrated,” he says. “Also, dietary habits play an important role, especially limiting salt intake.”

Both men and women develop kidney stones, he says. And while kidney stones are most common between ages 40 and 60, people of any age can get them, even children and teens.

Other risk factors include high blood pressure, obesity, diabetes, gout, bowel conditions that cause diarrhea (Crohn’s disease, ulcerative colitis), bariatric surgery, recurrent urinary tract infections and certain thyroid diseases.

Having a family history of kidney stones also may increase your risk, Dr. Friedlander says.

“The question becomes, is the increased risk genetic or environmental?” he says. “It could be their diet, or that they’re not drinking enough water. It’s hard to tease out a reason.”

Symptoms of Kidney Stones

Symptoms will differ depending on the person, the size of the stone, and where it is in the kidney or ureter (the tubes that connect your kidneys to your bladder), Dr. Friedlander says.

“The most classic symptom is acute-onset flank (lower back) pain,” he says. “Sometimes the pain will wax and wane, and sometimes it’s constant. Depending on the size of the stone and where it is, the pain will continue. A pain reliever may help, or the stone may reposition so it’s more nagging than acute.”

Other symptoms include stomach pain that doesn’t go away, blood in the urine, nausea or vomiting, fever and chills, and urine that smells bad or looks cloudy.

But many of these symptoms are the same for other abdominal conditions, including appendicitis, urinary tract infections and stomach viruses. Check with your primary care provider to know for certain. Kidney stones are commonly diagnosed through a medical history, physical examination and imaging tests (CT scan). If your doctor determines that you have a kidney stone, they will want to know its exact size, shape and location to decide on treatment.

Treatment for Kidney Stones

The best treatment for kidney stones depends on the size and location of the stone, Dr. Friedlander says.

“Only about 10 percent of people with a stone will require surgery to treat it,” he says. “The vast majority pass on their own with hydration or medications to facilitate the passage of the stone.”

If the stone is smaller than a centimeter, you may be able to pass it by increasing the amount of water you drink daily. Or you may be given a medicine that can relax muscles in the ureter, making it easier for the stone to pass through.

“We usually give patients up to four weeks to try and pass the stone,” he says. “At that point, if they haven’t passed it, we have to consider other treatments.”

Those treatments could include:

  • Shock wave lithotripsy: High-energy shock waves are used to blast the stones into fragments that are more easily passed in the urine. The treatment may need to be repeated before the stones are passed, Dr. Friedlander says.
  • Ureteroscopy: An endoscope (with a camera, laser fiber and small wire basket) is inserted through the ureter to find and snare smaller pieces of the stones. A stent (tube) may be placed in the ureter to hold it open.
  • Percutaneous nephrolithotomy/nephrolithotripsy: To remove large stones (marble-sized or bigger), a surgeon enters the kidney through a small incision in the back. A camera and other instruments are used to extract the stones, breaking them up first if necessary.

How to Prevent Kidney Stones

Since kidney stones form when your urine contains high levels of certain substances, the best prevention is to dilute your urine. That means drinking water—lots of it.

“I suggest drinking about 100 ounces of fluid a day,” Dr. Friedlander says. “If you’re drinking that much fluid, it’s unlikely you will get kidney stones.”

That’s the equivalent of about six 16-ounce bottles. If that sounds like a lot, remember you’re sipping gradually, not chugging all at once.

“The key is to space it out through the day,” he says. “Then drinking that much is more attainable.”

But make sure you talk to your doctor before increasing your water intake dramatically.

“If you are being treated for heart failure or poor kidney function, you may not be able to drink that much water,” Dr. Friedlander says. “Talk to your doctor first.”

Another step you can take to help prevent kidney stones is to limit your daily salt intake to less than 2,000 milligrams.

“Watch eating too much fast food,” he says, “or you can quickly exceed that allotment.”

Your doctor can do tests to see if other conditions are causing you to form kidney stones. For example, overactive parathyroid glands can make too much hormone and raise calcium levels, resulting in kidney stones. Treating any related conditions can solve the problem of kidney stones.

“The two most important things, though, are to increase fluids and reduce salt,” Dr. Friedlander says. “Even if you can’t drink 100 ounces, increasing your daily intake will help.”

If you are having symptoms that could be kidney stones, talk to your doctor, or find one near you.