Increases in global temperatures and greenhouse gas emissions may put more people at risk of developing kidney stones, according to a new study.
“These findings point to potential public health effects associated with global climate change,” study leader Gregory Tasian, MD, MSc, of the Children’s Hospital of Philadelphia, said in a statement. But Tasian also noted that the study, published online today in Environmental Health Perspectives, should be interpreted with a caveat.
“Although 11% of the US population has had kidney stones, most people have not,” he said. “It is likely that higher temperatures increase the risk of kidney stones in those people predisposed to stone formation.”
Tasian and his colleagues analyzed medical records for more than 60 000 adults and children treated for kidney stones between 2005 and 2011 in Atlanta, Chicago, Dallas, Los Angeles, and Philadelphia. They then compared the records with weather data from the National Climatic Data Center.
The investigators found that the risk of developing kidney stones increased during the study period in all the cities except Los Angeles when mean daily temperatures rose above 50°F (10°C). Mean daily temperatures reaching 86°F (30°C) were linked with risk increases of 38% in Atlanta, 37% in Chicago, 36% in Dallas, and 47% in Philadelphia compared with 50°F (10°C).
Higher temperatures contribute to dehydration, which leads to higher concentrations of calcium and other minerals in the urine, which promotes kidney stone development.
Kidney stone risk peaked within 3 days of exposure to high temperatures but then decreased within 7 to 10 days afterward. A similar phenomenon has been reported in heat-related deaths, the investigators noted.
In the broader context of warming weather patterns, the investigators said published climate science reports show that the global mean temperature between 2000 and 2009 was warmer than 82% of temperatures during the last 11 300 years. Also, that continued greenhouse gas emissions are projected to increase average temperatures worldwide by 34°F (1°C) to 40°F (4.5°C) by 2100.
“Kidney stone prevalence has already been on the rise over the last 30 years, and we can expect this trend to continue, both in greater numbers and over a broader geographic area, as daily temperatures increase,” Tasian said.