Global Warming and Risk of Renal Stone Formation

Abstract

A possible role of ambient temperature and climate as significant risk factors for urinary lithogenesis has been confirmed by several studies. Chronic dehydration associated to hot climate, outdoor working in the tropics, and military duty in a desert environment, all strongly increase the risk of developing kidney stones. Seasonal variation of the number of kidney stone-related colic attacks was frequently, although not consistently, reported; similarly, ambient temperature and hours of sunshine, but not humidity, were found to be positively associated with acute presentations of urinary calculi. Urine volume, sodium content, and pH are significantly lower in summertime and, consequently, the relative saturation of uric acid and calcium oxalate are higher (particularly in men). In addition to seasonal changes, there are also evident historical variations of the temperature at Earth's surface. There are numerous estimations of the temperatures during the previous 12,000 years that followed the last glacial period. During this era there have been warmer as well as cooler periods, although the mean global surface temperatures over the last 25 years have been higher than those of any comparable period in the last millennium. This climatic trend, named “global warming”, seems to be caused primarily by human-induced emissions of greenhouse gases. There is a growing consensus about the fact that during the 21st century we will indeed see a change of 2C° or more in additional warming. A secondary effect of the “global warming” may be an increase in the prevalence rate of kidney stones, which computer models estimate will be up to 10%.