Rising temperatures and increased dehydration linked to global warming will boost kidney stone rates in the United States and around the world, new research suggests.
In the United States in particular, hotter weather will lead to a dramatic rise in kidney stone disease among residents of southern states -- the so-called "kidney-stone belt." This will result in an increase of 1.6 million to 2.2 million additional kidney stone cases by 2050, according to the study.
"This is an example of how global warming will affect people directly," said study author Tom Brikowski, an associate professor with a specialty in hydrology in the department of geosciences at the University of Texas at Dallas.
The study authors stressed that the exact degree of the increased risk remains unclear. But, Brikowski added, "We are certain that warming will increase, and that the rate of kidney stone disease will go up. So as a nation, we will have to pay more attention to this problem."
The findings are reported in this week's issue of the Proceedings of the National Academy of Sciences.
Brikowski and his colleagues said the "kidney-stone belt" currently includes Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Tennessee. But with global warming, the risk of kidney stone disease could ultimately touch a much wider swath of states, stretching from Kentucky all the way to northern California, the researchers said.
According to the U.S. National Kidney and Urologic Diseases Information Clearinghouse, about 5 percent of Americans develop kidney stones at some point, with the risk rising as men and women enter their 40s and 50s, respectively.
Typically composed of calcium and other minerals found in urine, a kidney stone is a hard, crystallized mass that passes -- often painfully -- through the urinary tract. Drinking too little fluid and/or dehydration can lead to development of a stone, as can a metabolic predisposition for kidney stone disease, known as nephrolithiasis.