LOS ANGELES, CA (Catholic Online) - According to a new study, in 1994, one in 20 people in the U.S. had kidney stones. In the years between 2007 and 2010, the rate was one in 11.

"While we expected the prevalence of kidney stones to increase, the size of the increase was surprising," study researcher Dr. Charles Scales Jr. says. Scales is an urologist at the David Geffen School of Medicine at the University of California, Los Angeles.

"The kidney acts as a filter for blood, removing waste products from the body and making urine. It also helps regulate electrolyte levels that are important for body function. Urine drains from the kidney through a narrow tube called the ureter into the bladder. When the bladder fills and there is an urge to urinate, the bladder empties to the outside through the urethra, a much wider tube than the ureter," Dr. Benjamin Wedro writes in his online column.

"In some people, chemicals crystallize in the urine and form the beginning, or nidus, of a kidney stone. These stones are very tiny when they form, smaller than a grain of sand, but gradually can grow over time to 1/10 of an inch or larger.

"Urolithiasis is the term that refers to the presence of stones in the urinary tract, while nephrolithiasis refers to kidney stones and ureterolithiasis refers to stones lodged in the ureter. "The size of the stone doesn't matter as much as where it is located and whether it obstructs or prevents urine from draining," Wedro adds.

"When the stone sits in the kidney, it rarely causes problems, but when it falls into the ureter, it acts like a dam. As the kidney continues to function and make urine, pressure builds up behind the stone and causes the kidney to swell. This pressure is what causes the pain of a kidney stone, but it also helps push the stone along the course of the ureter. When the stone enters the bladder, the obstruction in the ureter is relieved and the symptoms of a kidney stone are resolved."
Researchers in the study also found that people with obesity, diabetes or gout were more likely than healthy people to be diagnosed with kidney stones.

Kidney stones can be successfully treated. They can also be prevented by eating a healthy balanced diet and getting plenty of exercise, researchers said. Researchers say doctors should shift their focus to prevention, especially now that more people in the U.S. are facing the condition.

"People should consider the increased risk of kidney stones as another reason to maintain a healthy lifestyle and body weight," researcher Dr. Christopher Saigal, associate professor of urology at the UCLA medical school says.

The study used data on 12,000 people collected during the National Health and Nutrition Examination Survey. The study is an ongoing survey conducted by the Centers for Disease Control and Prevention. Survey participants answer questionnaires, and undergo physical exams.

The study was released online and will appear in the July issue of the journal European Urology.

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