There’s one thing that most people do know about kidney stones, and that is that they can be excruciatingly painful. About 5% of Americans suffer from recurring kidney stones that cause moderate to severe pain.
Good news: Kidney stones can often be prevented with simple lifestyle changes. And for those that can’t be prevented, there are a variety of treatments that can rid you of kidney stones quickly and painlessly.
A kidney stone is a hard mass that forms from crystals in the urine. It occurs when certain components in urine, such as calcium, salts or other minerals, become too concentrated to dissolve fully, and they form a crystal deposit on the wall of the kidney instead. As the stones grow, most eventually break off and are passed out through the urine. Passing a stone can take days or weeks. About 90% of stones pass spontaneously. When they are small enough in size, they pass unnoticed.
The degree of pain and discomfort patients experience depends on the stone’s size and where it is located. While still in the kidney, larger stones may cause significant pain in the lower back on one side, sometimes accompanied by nausea and vomiting. As the stone progresses through the urinary tract, the pain typically shifts to the lower abdomen and then to the groin until the stone is finally excreted. If you experience any of these symptoms, inform your primary care doctor. He/she will first determine if you have a kidney stone and then monitor it, watching for possible obstruction or infection, either of which can lead to permanent kidney damage. See a doctor immediately if you experience...
Extreme pain in your back that doesn’t go away.
Blood in your urine.
Burning feeling when urinating.
Your doctor may recommend a precautionary X-ray to make sure that the kidney stone is not causing a blockage.
Important: If, in addition to these symptoms, you develop signs of an infection, particularly fever and chills, go directly to an emergency room. Infections related to kidney stones can be life-threatening if not treated right away.
If you get a kidney stone, there’s a 50% chance that you’ll have another unless you take steps to prevent a recurrence.
The most important preventive step is to stay well-hydrated. Studies show that by drinking 96 ounces (three quarts) of water or other nonalcoholic fluid daily, you can prevent half of all kidney stones. Crystals are less likely to form in a well-hydrated urinary tract, and those that do form tend to get flushed out of the body while still small.
Drink at least 12 ounces (of your daily 96 ounces) of water before going to bed (even if it means getting up to urinate) and six ounces if you wake during the night, so that your urine doesn’t become too concentrated while sleeping.
Other preventive measures depend on the type of kidney stones you have. To determine this, your physician will send your urine and an actual stone, if possible, to a lab for analysis. (If you have a stone that’s about to pass, you can retrieve it by urinating through a strainer.) Types of stones include...
Calcium stones. Eighty percent of kidney stones consist of calcium oxalate, from too much calcium in the urine... too much oxalate... and/or too little citrate, a chemical that helps calcium dissolve in urine.
Prevention advice: Avoid ingesting more than 2,000 milligrams (mg) of vitamin C daily (with larger doses than this, vitamin C metabolizes into oxalate).
Don’t consume more than two grams (g) daily of calcium-vitamin D supplements or 1,200 mg of calcium and 400 international units of vitamin D, if taken separately. (Vitamin D increases calcium absorption, which can lead to excess calcium in the urine.)
If a 24-hour urine collection test shows high oxalate levels, stay away from foods high in oxalate, including rhubarb, spinach, beets, swiss chard, wheat germ, peanuts, okra, chocolate and sweet potatoes. If your calcium oxalate stones are due to low citrate levels, potassium citrate (in tablet or liquid form) may be prescribed. A low-calcium diet is not recommended.
Reason: A moderate amount of dietary calcium is needed to bind with dietary oxalate -- otherwise, too little calcium in the diet can cause oxalate levels in urine to rise. Your doctor will decide how frequently your urine needs to be checked based on your particular needs.
Uric acid stones. These form when urine contains excess uric acid, a product of protein metabolism. Uric acid stones can result from a high protein diet and are also associated with gout, a form of arthritis in the foot or big toe caused by excess uric acid accumulation.
Prevention advice: Cut down on the amount of protein in your diet. Also: Uric acid is considerably more soluble in a nonacidic urine. Since potassium citrate makes urine less acidic, it may be prescribed for uric acid stones.
Calcium phosphate stones. These have been linked to the consumption of a large amount of antacid medication containing calcium carbonate.
Prevention advice: Switch to a calcium-free antacid.
Struvite stones. These stones are caused by urinary tract infections. They can become large and fill the entire urine-collecting space of the kidneys, in which case they become impossible to pass. Since these stones generally do not pass naturally, you must have the stone removed and treat the underlying infection aggressively to avoid recurrence.
Medical treatment for a kidney stone depends on its size. Smaller stones of four millimeters (mm) or less in diameter have an 80% to 90% chance of passing on their own. A stone of five mm has only a 20% chance of passing, while a stone that is eight mm or larger will almost never pass on its own. Smaller stones -- in the two mm to four mm range -- may also be difficult to pass if they have a jagged shape.
Usually, if a patient has a history of kidney stones that have passed spontaneously, and already knows how to deal with them, his doctor will recommend waiting a few weeks to see if the stone passes on its own.
For stones in the four mm to five mm range that are large but still passable, your doctor may prescribe medication, such as an alpha blocker or a calcium channel blocker, to relax the muscles and make more room for the stone to pass through the ureter. With these medications, 80% of such stones pass on their own within a month. Ideally, the patient should always urinate through a strainer to capture the stone, then bring it to the doctor for analysis. This is not always practical. But you may know the stone has passed because you feel it pass and/or see it in the basin of the toilet.
If your kidney stone is too large to pass, several approaches can be used to remove it...
In extracorporeal shock wave lithotripsy (ESWL), short bursts of focused acoustical energy are aimed at the stone from outside the body. ESWL fractures the stone into several smaller pieces that can be passed out through the urine.
In ureteroscopy, an outpatient procedure, a small endoscope (a thin, flexible scope typically with a light and camera at the end) is inserted through the urethra and bladder into the kidney. Stones less than 3 mm are pulled out using the scope. With larger stones, an attached laser is used to break up the stone. The small pieces then pass on their own.
Very large stones are treated using percutaneous nephrolithotomy (PCNL), an inpatient procedure.
How it works: With the patient under general anesthesia, the kidney is punctured with a needle through an incision in the back and a large scope is threaded into the kidney. An attached device -- either a vibration source, an ultrasonic energy source or a laser -- is used to break the stone into fragments, which are then sucked out through the scope.
Source: Lawrence Gibel, MD, urologist in Albuquerque. A urologic surgeon, he is associate professor of urology at the University of New Mexico Health Sciences Center and director of lithotripsy and staff urologist at the Albuquerque Veterans Affairs Medical Center.