If you’ve ever endured the searing pain of a kidney stone—it’s often described as worse than childbirth—then you probably felt like celebrating once the pain was gone and now consider yourself home free. But that’s a mistake.
What most people don’t realize: Once you’ve suffered a kidney stone, which can be as small as a grain of sand or as large as a golf ball, you have a chronic condition that must be managed over a lifetime to prevent a repeat performance.
Here’s what you need to know to control this condition over the long haul—and prevent it in the first place if kidney stones run in your family…
Even if you’ve never had a kidney stone, that doesn’t mean you’re in the clear. About one in every 10 Americans will have a kidney stone during his/her lifetime.
Eye-opening new finding: For unknown reasons, the prevalence of kidney stone disease has doubled in the past 15 years—more than three million Americans receive medical care for the condition each year.
Treatment for a kidney stone mainly depends on its size. If you develop a small stone (less than 4 mm—or about one-sixth of an inch), count yourself lucky. You may be able to simply drink lots of water (about three liters per day)…take an over-the-counter nonsteroidal anti-inflammatory drug, such as ibuprofen (Motrin)…and wait for it to pass on its own within a few days, though it sometimes takes a week or longer. A prescription medication, such as tamsulosin (Flomax), may also be used to help pass the stone. Important: It’s crucial that a urologist monitor the patient (for example, with an abdominal X-ray or ultrasound), since the stone may cause an obstruction that damages the kidney—even if the pain has subsided.
A larger stone (4 mm or more) usually needs more extensive medical intervention. While doctors once relied on external sound waves (shock wave lithotripsy), which was only moderately successful at breaking apart a kidney stone in the body, there’s now a more effective method. An ultrathin lighted tube (ureteroscope) can be threaded into the urethra, into the bladder, then up to the ureter. A laser at the tip of the scope pulverizes the stone, turning it into dust that is urinated out.
When a kidney stone exceeds 2 cm (or about three-quarters of an inch), surgery is usually required. With percutaneous nephrolithotomy, the surgeon creates a small incision in your back to remove the stone.
To avoid a recurrence, the key is to know the composition of your kidney stone. Main types of stones…
• Calcium oxalate. These small, black or dark brown stones account for about 80% of all kidney stones.
• Calcium phosphate. These stones, which are usually tan to beige, form when urine is more alkaline.
• Uric acid. These red or orange stones form when urine is too acidic due to heredity, obesity or kidney disease.
• Cystine. These lemon yellow stones are associated with the hereditary disorder cystinuria, which causes high urine concentrations of the amino acid cystine.
• Struvite. These brownish-white stones are produced when bacteria get introduced into the urinary tract—due, for example, to the use of a urinary catheter.
To prevent a kidney stone recurrence, your goal is to stop the stone-forming process by changing the composition of your urine.
Here’s how to do that…
STEP 1: Get your kidney stone analyzed. If you pass a stone at home, save it so that your doctor can have its composition analyzed. Urine analysis shows what stone-causing compounds are in your urine so that you can take appropriate preventive steps. What to do: Strain your urine through gauze in a funnel and then put the stone into a small plastic bag.
Important: It’s best to have all stones analyzed, since your kidneys can produce stones of varying crystals at different times in your life, which may require a change in treatment. Anyone who has ever suffered a kidney stone should also see a doctor at least once a year for urine analysis.
STEP 2: Provide two 24-hour urine samples after the stone has passed. This requires catching and saving all your urine for 24 hours after you’ve resumed your normal diet and lifestyle habits. Getting two samples provides a more accurate view than a single sample.
STEP 3: Raise your urine volume. The more dilute your urine becomes, the less likely that stones will form. The goal is to produce about 2.5 liters daily in urine volume. This will require drinking three liters or more of fluid daily (spaced out during waking hours). People who sweat a lot due to heat or physical activity may need to drink four to six liters of water per day.
Note: High water intake can sometimes be harmful for people with heart, kidney or liver disease…the elderly…and people taking certain medications (such as diuretics). Consult your physician for advice on how much water you should drink.
STEP 4: Change your diet. This should start immediately when you have a kidney stone and continue for a lifetime. A kidney stone prevention diet is…*
• Low sodium and high calcium. If your daily sodium intake is below 1,500 mg, you can eat 1,000 mg to 1,200 mg of calcium daily (mainly from dairy foods and leafy green vegetables, except for spinach), and urine calcium losses will be as low as possible. Why do you need calcium? High calcium intake will reduce oxalate absorption—oxalate is a component of most kidney stones. Helpful: After following a low-sodium/high-calcium diet for about a month, repeat the 24-hour urine test to see if additional dietary restrictions are required.
Important: If urine oxalate remains high (over 30 mg per day) despite a high calcium intake, then you need to go low oxalate. To reduce your risk for calcium oxalate stones, avoid high-oxalate foods (such as spinach, rhubarb, beets, cocoa, raspberries and soy products). Note: Even though many of these foods are healthful, there are safer substitutes—for example, instead of spinach, you can try arugula or kale. For a full list of high-oxalate foods and good substitutes, go to KidneyStones.UChicago.edu/how-to-eat-a-low-oxalate-diet.
• High potassium. When food sources of potassium—all fruits and most vegetables—are consumed, they are converted to bicarbonate. This process reduces the risk for calcium and uric acid stones. Recommended daily potassium intake: 4,700 mg.
• Low protein and refined sugar. These foods can promote uric acid stones. Ideally, intake of refined sugar should be less than 10% of total caloric intake, and protein intake should be about 0.8 g to 1 g of protein per 2.2 pounds of body weight.
STEP 5: Ask your physician about medication. A variety of medications can help prevent a kidney stone recurrence. These include potassium citrate tablets for people who have had uric acid stones or calcium stones…thiazide diuretics, which help prevent calcium stones…and antibiotics for struvite stones that are triggered by, say, a urinary tract infection.
For more on kidney stones, go to KidneyStones.UChicago.edu.
When a stone forms in the kidney, it typically moves through the urinary tract to exit the body in urine. At various points along that journey, the stone may become lodged, leading to extreme pain (usually in one’s side or back near the bottom of the rib cage, though it may spread to the lower abdomen and groin).
Important: Kidney stones may also cause blood in the urine, an inability to pass urine, nausea and vomiting and/or fever and chills. Get to an emergency room if you suffer from any of these symptoms—they may signal an infection that requires immediate medical care.
*If you have chronic kidney disease, your dietary and treatment needs may differ—consult your doctor.
