A kidney stone is a solid piece of material that forms in a kidney when substances that are normally found in the urine become highly concentrated. Kidney stones are one of the most common disorders of the urinary tract, accounting for more than 1 million visits to healthcare providers in the U.S. each year.
What causes kidney stones?
Chemicals in the urine can sometimes form crystals. These are like little bits of sand. If the crystals stick tougher, they become a hard mass called a stone. Minerals associated with kidney stone formation include calcium, oxalate and phosphorus.
People who do not drink enough fluids may be at higher risk for developing a stone because their urine is more concentrated. Certain foods may promote stone formation in people who are susceptible.
There are a number of conditions that increase one’s risk of developing kidney stones. These include:
- Cystic kidney diseases
- Renal tubular acidosis
A family history of kidney stones; blockages of the urinary tract; chronic inflammation of the bowel; history of gastrointestinal surgery; and use of certain medications including diuretics and calcium-based antacids increases the risk of stone formation.
Treating kidney stones
Depending on the stone, where it’s located and your overall condition, there are several ways to treat a kidney stone.
Allow the stone to pass on its own. Many kidney stones can be allowed to pass normally in the urine. This may be done with or without the aid of medication. The decision to allow the stone to pass naturally depends on its size, type, location, your overall health and pain level.
Remove or break up the stone. If the stone is large, won’t pass or is associated with an infection, it may be necessary to remove the stone. Options include:
- Shockwave lithotripsy. This is the most common procedure used to treat kidney stones and uses sound waves to break stones into small pieces. This makes it easier for the body to pass the stones. It is usually recommended for stones in the kidney and the upper ureter (the tube that passes urine from the kidney to the bladder).
- Ureteroscopy. When a stone is lodged in the ureter, the doctor may insert small instruments through the urethra and bladder up to the ureter. A fiber optic laser can be used to break up the stone, which can then pass in the urine. If the stone is small, a tiny basket can be sent through the instrument to grasp the stone and remove it.
- Percutaneous stone removal. This procedure is used for larger stones located in the kidney. A small incision is made in the back and a scope with a camera is inserted through the incision into the kidney. Lasers or other devices are passed through the scope to break up the stone. The fragments are removed through the scope.
Who gets kidney stones?
Anyone can get one, but some people are more likely to develop kidney stones than others. Men are affected more often than women, and kidney stones are more common in non-Hispanic white people. Overweight people are more likely to get a stone than those of normal weight. In the U.S., nearly 9 percent of the population, or one in 11 people, have had a kidney stone.
Avoiding kidney stones
You can reduce your risk of developing kidney stones by:
- Drinking plenty of fluids, especially water. This helps flush minerals out of your kidneys before they can build up and form stones. Doctors recommend drinking eight 12-ounce glasses of water daily.
- Following a healthy diet. If you’ve had a kidney stone, talk to your doctor about the type. This will help you avoid those foods that increase your risk. You may be told to:
- Limit your intake of sodium (salt) and animal proteins
- Avoid foods that are high in oxalates, such as chocolate, nuts, leafy green vegetables, black teas and colas
- Get the recommended daily allowance of calcium in your diet. Too much or too little calcium can contribute to kidney stones
- Avoid excessive amounts of vitamin C
- Lose excess weight