Rising global temperatures will likely bring more hot days and more dehydration - which is a "key risk factor for a surge in kidney stones," according to a recent study the Associated Press reported.

Researchers found a link between hot days and kidney stones in patients whose medical records were studied in Atlanta, Chicago, Dallas, Los Angeles and Philadelphia. They noticed that as daily temperatures rise, so does the number of patients seeking treatment for kidney stones.

"We found that as daily temperatures rise, there is a rapid increase in the probability of patients presenting over the next 20 days with kidney stones," Gregory E. Tasian, who led the study, said in a statement.

For the study, researchers analyzed medical records of more than 60,000 adults and children with kidney stones between 2005 and 2011 in Atlanta, Chicago, Dallas, Los Angeles and Philadelphia, in connection with weather data., the AP reported.

They found that as the daily temperatures in each city rose above 50 degrees Fahrenheit, the risk of developing kidney stone increased in all the cities except Los Angeles. people's risk spiked after just three days of exposure to high temperatures.

The researchers argue that the number of hot days in a given year may better predict kidney stone risk than the mean annual temperature. Atlanta and Los Angeles share the same annual temperature (63 F, or 17 C), but Atlanta has far more hot days than Los Angeles, along with nearly twice the prevalence of kidney stones.

"These findings point to potential public health effects associated with global climate change," said Tasian. "However ... although 11 percent of the [United States] population has had kidney stones, most people have not. It is likely that higher temperatures increase the risk of kidney stones in those people predisposed to stone formation."

Researchers conclude that higher temperatures contribute to dehydration, which leads to a higher concentration of calcium and other minerals in the urine that promote the growth of kidney stones.

The study team also found that low outdoor temperatures increased the risk of kidney stones in three cities: Atlanta, Chicago and Philadelphia. Researchers suggest that as frigid weather keeps people indoors more, higher indoor temperatures, changes in diet and decreased physical activity may raise their risk of kidney stones.

The findings were recently published in the journal Environmental Health Perspectives.