The long lazy days of summer are ending: The warm evenings, the iced tea, the sounds of kids playing at the pool being overshadowed by the loud moans of the patient with kidney stones ….
Kidney stones (nephrolithiasis) are collections of crystals that coalesce into a hard ball and can lodge in any location of the urinary collecting systems. More than half a million patients seen in US emergency departments each year will receive a diagnosis of nephrolithiasis.1
But the problem is much more common in the summer, thanks to the double whammy of heat and humidity.2-4 Research indicates that it is not geographic area but instead the effects of climate that impact stone incidence.5 As climate change occurs, it is expected that the incidence of kidney stones will rise.
There is a “stone belt” that covers the southern portion of the United States (see Figure). As reported in Kidney International, this area is growing due to climate change and is expected to reach as far north as Nebraska, Illinois, Pennsylvania, and Oregon by 2095. Thus, the incidence of stone formation will increase throughout the 21st century in many parts of the US.6
Kidney stones are more common in men than in women and in white than in nonwhite persons (by three to four times). Peak incidence occurs between ages 20 and 50.1 Heat plays a greater role in the increased incidence of stone formation in men for unknown reasons.6
Stones that lodge in the ureter or the calyces of the kidney will often cause obstruction. When the flow of urine is obstructed, infection, loss of kidney function, and chronic permanent damage can result. Thus, decreasing the incidence of stones is vital at any time of the year—but most significant during the summer.
All patients with a history of stones require fluid hydration, up to 2.5 L/d, with extra intake during the heat of summer.7 Patients who travel to hot, humid regions must be encouraged to increase fluid consumption. Often, foreign travel can be problematic due to a decrease in access to clean drinking water and/or lavatory facilities. It is incumbent upon the practitioner to review risk for kidney stones with patients who plan to travel to warm areas.
As the summer season closes and school starts, this is a perfect time to review the causes, treatment, and most importantly, the methods to decrease recurrent kidney stone formation with patients. Each incident of stone formation for our patients can translate to an increased incidence of chronic kidney disease and a 50% risk for another stone during their lifetime.1
REFERENCES
1. National Kidney Foundation. Kidney stones. www.kidney.org/atoz/content/kidneystones.cfm. Accessed September 10, 2014.
2.Schade GR, Faerber GJ. Urinary tract stones. Prim Care. 2010;37(3):565-581, ix.
3. Pearle MS, Calhoun E, Curhan GC. Urolithiasis. In: Litwin MS, Saigal CS, eds. Urologic Diseases in America. National Institute of Diabetes and Digestive and Kidney Diseases. 2007:281-320. http://kidney.niddk.nih.gov/statistics/uda/Urologic_Diseases_in_America.pdf. Accessed September 10, 2014.
4. Romero V, Akpinar H, Assimos DG. Kidney stones: a global picture of prevalence, incidence and associated risk factors. Rev Urol. 2010;12(2-3):e86-e96.
5. Eisner BH, Sheth S, Herrick B, et al. The effects of ambient temperature, humidity and season of year on urine composition in patients with nephrolithiasis. BJU Int. 2012;110(11c):E1014–E1017.
6. Fakheri RJ, Goldfarb DS. Ambient temperature as a contributor to kidney stone formation: Implications of global warming. Kidney Int. 2011;79:1178–1185.
7. Lipkin ME, Preminger GM. Demystifying the medical management of nephrolithiasis. Rev Urol. 2011;13(1):34-38.