Their study will be published in the April issue of Kidney International and is currently available online. These findings for the first time directly link excess body weight with uric acid kidney stones, found in about 5 percent of kidney-stone patients and in about 30 percent of diabetics with kidney stones.

"This is yet another price to pay for being overweight or obese," said Dr. Khashayar Sakhaee, program director of the General Clinical Research Center (GCRC) at UT Southwestern.

An estimated 10 percent of people in the United States will have a kidney stone some time in their lives.

Kidney stones are solid deposits that form in the kidneys from substances excreted in urine. When waste materials in urine do not dissolve completely, microscopic particles begin to form and over time grow into kidney stones. These stones may remain in the kidney or can break loose and travel down the urinary tract. Small stones may pass out of the body naturally, but a larger stone can get stuck in a ureter, the bladder or the urethra, possibly blocking the flow of urine and often causing intense pain.

Uric acid kidney stones develop when the urine's acid level is too high, typically from the ingestion of too much dietary animal protein or when there are insufficient amounts of buffers to neutralize acid in the urine.

The latest study, which included researchers at the University of Chicago, tracked nearly 5,000 kidney-stone patients in Dallas and Chicago. Results did not vary between men and women, nor for patients who restricted the types of foods eaten.

"Larger people have very acidic urine even when they control their diets," said Dr. Sakhaee, professor of internal medicine at UT Southwestern. "Other studies we have done in the
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Contact: Donna Steph Hansard
donna.hansard@utsouthwestern.edu
214-648-3404
UT Southwestern Medical Center
22-Mar-2004