stated the link was discovered in a scientific study that both reflected and warned of the warming planet's impact on human health.
"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," said study leader Gregory E. Tasian, M.D., M.Sc., M.S.C.E., a pediatric urologist and epidemiologist at The Children's Hospital of Philadelphia (CHOP), who is on the staff of the Hospital's Kidney Stone Center as well as the Hospital's Center for Pediatric Clinical Effectiveness (CPCE).
The study was sponsored by the Urology Diseases in America Project, which is supported by the National Institute of Diabetes and Digestive and Kidney Diseases. Results of the study were published in Environmental Health Perspectives
, the journal of the National Institute of Environmental Health Sciences
Primary data in study
Running from 2005 to 2011, the medical records of adults and children with kidney stones from Atlanta, Chicago, Dallas, Los Angeles and Philadelphia, were analyzed in connection with weather data. Team leader Tasian and his colleagues "...described the risk of stone presentation for the full range of temperatures in each city," according to CHOP
There was an increased risk of kidney stone presentation as the mean daily temperatures rose above 50 F (10 C) in all cities except Los Angeles. Peaking with three days of exposure to the hot days, the delay between high daily temperatures and kidney stone presentation was short.
According to the Children's Hospital of Philadelphia
, "These findings point to potential public health effects associated with global climate change," said Tasian. "However," cautions Tasian, "although 11 percent of the U.S. 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." 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.
Patterns of global warming
When the study was ran, its broader context was patterns in global warming. Scientists in general have previously reported that global temperatures from 2000 to 2009 were higher than 82 percent of temperatures over the past 11,300 years.
Additionally, the increase in greenhouse gas emissions are expected to rise above the earth's temperatures from 2 to 8 degrees F. 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,” concluded Tasian, in the CHOP interview. “With some experts predicting that extreme temperatures will become the norm in 30 years, children will bear the brunt of climate change.”
Conclusions of Tasian's study
In general, kidney stone presentations increased with higher daily mean temperatures, with the strongest associations estimated for lags of only a few days. These findings further support an adverse effect of high temperatures on nephrolithiasis.