Global Warming May Be to Blame For Increase in Kidney Stones

An increasingly warmer U.S. climate may lead to more people suffering from kidney stones. Because dehydration is one of the risk factors for kidney-stone disease, and hotter temperatures cause more fluid loss, kidney stones are projected to become more likely, according to researchers at the University of Texas at Dallas and the University of Texas Southwestern Medical School.

After analyzing the frequency of kidney stones in the U.S. and studying expected nationwide average annual temperature increases, Tom Brikowski, Ph.D. and colleagues predict that by 2050, warmer temperatures will cause an extra 1.6 million to 2.2 million kidney-stone cases This increase represents up to a 30 percent growth in some areas.

Global warming may expand the higher-risk region of the Southern U.S. known as the "kidney-stone belt" into neighboring states. The states currently included are Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Tennessee. An increase in the number of kidney stone related health issues in the upper Midwest is also possible with the Chicago area alone getting up to 100,000 extra cases each year. Other countries may be affected as well. The report can be found in the July 14 issue of the Proceedings of the National Academy of Sciences.

According to Dr. Margaret Pearle, professor of urology at UT Southwestern and senior author of the paper, "This study is one of the first examples of global warming causing a direct medical consequence for humans." She also noted, "There is a known geographic variation in stone disease that has been attributed to regional differences in temperature. When people relocate from areas of moderate temperature to areas with warmer climates, a rapid increase in stone risk has been observed. This has been shown in military deployments to the Middle East for instance."

Kidney-stone disease (nephrolithiasis) is a common health issue in which solid crystals form from dissolved minerals in urine. Both environmental and metabolic issues cause kidney stones. The lower the volume of urine, the higher the kidney stone risk due to the concentration of stone-forming salts. Therefore, kidney stones can from either too little fluid intake or too much fluid loss.

The researchers used models of global warming from the Intergovernmental Panel on Climate Change's 2007 Fourth Assessment Report that predict temperature increases based on anticipated future greenhouse gases. It is the belief of most climate researchers that carbon dioxide and other greenhouse gases being emitted are raising global average temperatures with the expectation that North America will see an increase of at least 2 degrees Fahrenheit within the twenty-first century.

By using two studies that reported kidney stone rates in different geographic regions and comparing regional rates with annual averages of local temperatures, the researchers obtained two mathematical models associating temperature with kidney stone risk. Both models predict that the current kidney-stone belt will expand with one model predicting the increase in the southern half of the country and the other forecasting an increase in the upper Midwest. Either way, the costs of treatment will increase astronomically. According to co-author Dr. Yair Lotan, assistant professor of urology at UT Southwestern, "Nationwide, the cost of treating these new kidney-stone cases could rise as high as $1 billion."

Federal estimates show that over 5 percent of the U.S. population has kidney stones that account for approximately half a million emergency room visits annually. Current treatment costs range from around $8,000 for noninvasive techniques to over $50,000 when surgery is necessary. Kidney stones are rarely fatal, but are considered one of the most painful medical conditions. The most common treatments of the ailment include utilizing shock waves produced by pulses of sound to blast the stone or destroying it with a small laser.

The federal Centers for Disease Control and Prevention (CDC) have warned that global warming could lead to lethal heat waves and more blooms of algae that infect our fish with toxins as well as widespread insect-borne illnesses such as Lymes disease and Rocky Mountain spotted fever. These are dangerously serious issues to consider. In comparison, a simple and effective way to counteract the effects of temperature on kidney stones is to stop adding salt to food and to drink two extra glasses of water each day.