A new study published in Environmental Health Perspectives (EHP) showed a rise in kidney stones during hot-weather spells. The study found that there were more incidences of kidney stones for three days following hot weather. This may mean that kidney stone prevalence will rise over the next few years, according to the study.

Researchers found in the study that as temperatures increased above 50°F (10°C) in several large U.S. cities, risk of kidney stones increased significantly. The study followed 60,433 privately insured patients in five cities -- Atlanta, Chicago, Dallas, Los Angeles, and Philadelphia. (Los Angeles did not show a statistically significant change, but each of the four other cities did.)

The stones were likely caused because hot weather can cause dehydration, and dehydration can cause kidney stones, the paper said.

Kidney stones are painful growths caused by a build-up of uric acid in the body. According to the study, kidney stone prevalence has been on the rise for the past 30 years. The authors of the study predict that trend will continue in the future as global warming continues. The relationship between kidney stones and hot weather is not clearly understood, but high ambient temperature is seen as a risk factor for kidney stones.

What does this mean? Gregory Tasian, the lead author of the study, is a pediatric urologist. He said in the paper, "These findings point to potential public health effects associated with global climate change... It is likely that higher temperatures increase the risk of kidney stones in those people predisposed to stone formation."

There are some limitations to the study, which the authors acknowledged. For example, the study did not track how much time patients actually spent outdoors. It is possible that many of the patients spent more time indoors, possibly using air conditioning. The study also didn't control for factors like age. However, this study may be the first signs of a troubling trend.