Global Warming Increases Kidney Stone Incidence in United States

Even though most of the southern US (as well as most of the rest of the US) shows no unprecedented warming, the alarmists are coming up with more bizarre warnings. In May 2008 the American Urological Association warned that global warming would cause increased kidney stones, based on the research by Pearle MS, Lotan Y, Brikowski T: “Predicted climate-related increase in the prevalence and cost of nephrolithiasis in the U.S.”, J Urol, suppl., 2008. Their press release [http://www.auanet.org/press/WebContent/WebView_News_Releases.asp?iRecordid=45&Area=MEETING%20%20kidney%20stones%20global%20warming] states: “Rising global temperatures could lead to an increase in kidney stones … researchers applied predictions of temperature increase to determine the impact of global warming on the incidence and cost of stone disease in the United States. … Dehydration has been linked to stone disease, particularly in warmer climates, and global warming will exacerbate this effect. … The southern United States is considered “the stone belt” because these states have higher incidences of kidney stones. Rising global temperatures could expand this region; the fraction of the U.S. population living in high-risk stone zones is predicted to grow from 40 percent in 2000 to 50 percent by 2050.”

This is rather bizarre considering that sources of information on kidney stone causes indicate otherwise. For example, the National Kidney and Urologic Diseases Information Clearinghouse (part of NIH) [http://kidney.niddk.nih.gov/kudiseases/pubs/stonesadults/index.htm#cause] states: “A person with a family history of kidney stones may be more likely to develop stones. … Other causes of kidney stones are hyperuricosuria, which is a disorder of uric acid metabolism; gout; excess intake of vitamin D; urinary tract infections; and blockage of the urinary tract. Certain diuretics, commonly called water pills, and calcium-based antacids may increase the risk of forming kidney stones by increasing the amount of calcium in the urine.” Other rare hereditary diseases are mentioned, but not dehydration. Another example, the Mayo Clinic [http://www.mayoclinic.com/health/kidney-stones/DS00282/DSECTION=3]: “Problems in the way your system absorbs and eliminates calcium and other substances create the conditions for kidney stones to form. Sometimes, the underlying cause is an inherited metabolic disorder or kidney disease. … It's common, however, for kidney stones to have no definite, single cause. … Roughly four out of five kidney stones are calcium stones, usually in the form of calcium oxalate. Oxalate is found in some fruits and vegetables, but the liver produces most of the body's oxalate supply. Dietary factors, high doses of vitamin D, intestinal bypass surgery and several different metabolic disorders can increase the concentration of calcium or oxalate in urine.” Dehydration is not mentioned.

In fact with Lotan and Brikowski’s statement of “The southern United States is considered “the stone belt” because these states have higher incidences of kidney stones”, they forgot that it is actually the southeast US that has that reputation, according to the National Institutes of Health (NIH) [http://www.ncbi.nlm.nih.gov/pubmed/8126805]: “Using the Southeast as the comparison region, a decreased risk of having a history of kidney stones was found, ranging from 13% (95% confidence interval 4 to 21%) lower in the Mid-Atlantic region to 31% (95% confidence interval 21 to 40%) lower in the Northwest. The prevalence in all other regions combined compared to the Southeast was also lower (odds ratio 0.82, 95% confidence interval 0.76 to 0.89). Therefore, individuals in the Southeast appear to have an overall greater risk of kidney stones”.

Recent studies have shown a link between kidney stones and obesity [http://www.webmd.com/kidney-stones/news/20050125/weight-gain-obesity-linked-to-kidney-stones]. Other studies have shown that obesity rates are highest in the southeast US [http://healthyamericans.org/newsroom/releases/release082305.pdf] and [http://www.jhsph.edu/publichealthnews/press_releases/2007/wang_adult_obesity.html]. Coincidence?

The following graph shows the Hadley Climatic Research Unit (HadCRU) data used by the IPCC for the four 5x5 degree grids covering most of the southeast US. No global warming there.