Kidney stones (which doctors refer to as renal calculi) are one of the most common disorders of the urinary tractand also one of the most painful. The stones themselves are small, solid lumps composed of minerals and crystallized salts that separate from urine and build up in the urinary tract.
Stones can form anywhere in the urinary tract but typically develop on the inner surfaces of one or both kidneys over a period of time. Once formed, the stones sometimes travel into and through the ureterand it is this passage through the ureter that can cause the intense pain.
Stones vary greatly in sizeas minuscule as a grain of sand to as large as a golf ball. Tiny stones may cause no symptoms when they pass through the ureter. But when a larger stone (whole or broken into pieces) moves out of the kidney and enters the ureter, it produces pain (renal colic) caused by the ureter contracting in order to squeeze the stone and urine through the tract. This singular distressmarked by frequent episodes of crescendoing paincontinues until the stone eventually makes its way along the ureter to the bladder, at the front of the body.
It’s estimated that 1 in 10 adults in industrialized countries will develop kidney stones at least once in their lives, with men outnumbering women four to one. White people are more prone to kidney stones than African-Americans, and most stone attacks affect people over the age of 30. At least half of those suffering a kidney stone attack will have a recurrence within five years if there is no medical intervention.
Symptoms of Kidney Stones
A kidney stone is usually asymptomatic until it is dislodged from the kidney and migrates into the ureter, a narrow tube connecting the kidney to the bladder. When that occurs, the primary symptom is pain, which typically begins in the back, just below the ribs. Waves of sharp pain occur every few minutes, and over the first few hours (or days) the pain will follow the path of the stone through the ureter. Men may experience pain in the testes and penis as the stone passes. Once the stone is passed, the pain stops. The following symptoms may also occur.
- Bouts of nausea and/or vomiting
- An urge to urinate but an inability to pass normal amounts at one time
- Blood in the urine
- Urine that looks cloudy or smells bad
- Burning sensation when urinating
- Fever and chills (if a concomitant infection is present)
- Excessive pain at the back or side
What Causes Kidney Stones?
All kinds of waste products are filtered out of the blood by the kidneys and excreted in urine. Stones are mixtures of mineral substances—chiefly calcium, magnesium, and phosphate, along with oxalic acid (mostly produced in the body, but also found in some foods), uric acid (an end product of metabolism from nucleic acids in animal products), and, rarely, the amino acid cystine. If these substances accumulate without enough fluid to carry them away, stones may form in susceptible people.
The most common stones are almost pure calcium oxalate; others are formed from a combination of calcium oxalate and calcium phosphate. A core has to form first, and then crystallization can begin. But why stones crystallize in some people and not others isn’t clear. A family history of stones has something to do with it. Also, certain disorders are linked to an increased risk. Recurrent urinary tract infections may create a chemical environment conducive to kidney stone development. High uric acid levels, sometimes associated with symptoms of gout, may also lead to the formation of uric acid stones. People with inflammatory bowel disease are also at increased risk of developing kidney stones. Bacterial infections in the kidney account for about 10 percent of cases.
Living in a hot climate may also be a factor. It’s thought that hot weather causes increased sweat loss and reduced urine production; thus the urine contains a higher concentration of stone-producing mineral content.
What If You Do Nothing?
Most stones are small, and are passed out in the urine without notice or pain. Large kidney stones may stay in the kidney and cause no problems. When a large stone does enter the ureter, it can cause pain that may last up to 72 hours or more and that sends many people to the emergency room. The pain stops once the stone passes into the bladder. While you may need medication to combat the pain, a stone usually passes without causing any complications.
If a large stone can’t pass, however, it can block the flow of urine and cause eventual kidney damage. To prevent this, the stone may need to be removed.
Home Remedies for Kidney Stones
Since 90 percent of all kidney stones are less than 5 millimeters in diameter, self-treatment typically consists of measures to promote their natural passage out of the body. But if the stone is large, you will probably need to contact your doctor to prescribe medication for pain relief, since over-the-counter pain relievers are rarely helpful. In addition, take the following measures.
- Flush the stone out. Drink at least three quarts of water a day to flush the small stone into the bladder. Drink even more when it’s hot outside. To be sure you are drinking enough, your urine should be almost colorless.
- Walk. If possible, go for a walk. This movement may speed up the passage of the stone.
- Trap the stone. The key to effective treatment and prevention is diagnosing the kind of stone you form. Each time you urinate, do so through a piece of gauze, cheesecloth, or strainer with a fine mesh to trap the stone when it passes. Give it to your physician for analysis to find its cause, which will help with more specific treatment. Most stones are made of complex salts of sodium or calcium, but stones composed of uric acid indicate you have a treatable metabolic disorder.
- Apply heat. Heat can reduce pain and discomfort associated with the kidney stones.
Since the exact cause of kidney stone formation is not known, avoiding them is practically impossible. If you have a history of stones, talk to your doctor about the preventive measures you should take. Kidney stones are a complex problem, and no single piece of advice is appropriate for all sufferers. The following measures may help prevent or reduce painful incidences in many people predisposed to this malady.
- Drink two to three quarts of water daily. Make sure your urine is pale yellow or almost colorless. Increase your intake of fluid in hot and humid weather.
- You probably don’t have to avoid calcium. A few stone formers do reduce their risk of recurrence when they cut down on calcium. But research suggests that getting the recommended amounts of calcium may actually help prevent stones in some people. This is good news, because eliminating calcium can harm bones and general health. And a low calcium intake may lead to higher oxalate levels. At the same time, don’t consume excessive amounts of calcium. Because treatment of stones should be individualized, you should consult your physician about this and other dietary measures if you have a history of stones,
- Consider limiting oxalate-rich foods. It’s well known that some stone formers reduce their likelihood of a recurrence by cutting back on certain foods. If you have too much oxalate in your urine (determined by a urine test), your physician may recommend that you lower your intake of spinach, rhubarb, black pepper, cheese, peanut butter, nuts, beer, tea, and chocolate. These contain oxalic acid—salts that bind with calcium ions and promote stone formation.
- Consider reducing your intake of animal protein. Some stones are specifically linked to certain kinds of protein in the diet, which leads to too much uric acid and calcium stone formation. Again, consult your physician. Changing the diet to help the body utilize calcium more efficiently or taking medicine to reduce uric acid may help prevent this type of stone.
- Keep your sodium intake low. A low-sodium diet—less than 2,400 mg a day—can reduce calcium in the urine. Avoid fast foods, as well as canned soups and other processed foods.
- Avoid crash weight-loss diets. Some fad diets, high-protein diets, and other plans for quick weight loss can cause a condition called ketonuria, which may increase uric acid production and thus tend to promote kidney stones. Habitual use of stimulant laxatives is also particularly bad for stone formers.
- Treat underlying urinary tract infections. People with chronic urinary tract infection often develop stones composed of struvite, which is a combination of magnesium, ammonium, and phosphate. Preventing urinary tract infection will prevent these struvite stones.
- Talk to your doctor about drug therapy. One type of medication, called thiazides, can keep calcium out of the urine. Allopurinol, another drug, can keep uric acid from forming. Medication to alter the acidity of urine may also be prescribed.
Beyond Home Remedies: When To Call Your Doctor
Contact your physician if you have symptoms of a kidney stone—especially if you have never had a stone. Also, contact your physician if you have blood in your urine, you begin to have a stinging or burning sensation when urinating, you have a frequent urge to urinate, or you develop a fever along with these symptoms.
What Your Doctor Will Do
Following a thorough history and physical examination, your physician may take specimens for urinalysis and blood studies to rule out kidney disease and to help diagnose kidney stone presence. The urinary tract may be x-rayed, or an ultrasound scan may be used to monitor the stones. Your doctor may prescribe pain medication or antibiotics and send you home until the stone passes. If a stone is blocking the ureter, the physician may recommend ultrasound shock wave treatment (lithotripsy, a non-invasive procedure) or laser surgery (an invasive procedure) to break the stone into smaller pieces. After removal of a stone, your doctor will assist you in developing a program to prevent further stone formation.
The Complete Home Wellness Handbook
John Edward Swartzberg, M.D., F.A.C.P., Sheldon Margen, M.D., and the editors of the UC Berkeley Wellness Letter
Updated by Remedy Health Media