Sunburn and sunstroke are often what people fear when a heat wave is coming. But when the temperatures soar, so does the risk for your kidneys. Recurrent heat exposure and inadequate hydration strains the kidneys, especially if there’s a pre-existing kidney condition. And frequent dehydration, even if it’s mild, may lead to kidney damage.
Research published in the Clinical Journal of the American Society of Nephrology suggests that the increase in heat waves due to climate change may be associated with the rise in kidney diseases detected in outdoor workers subjected to longer hours and days of heat and dehydration.
Here’s what you need to know to give your kidneys the extra care they need as summer arrives.
The Dangers of DehydrationThe kidneys cleanse our blood and maintain the normal balance of salt and water. The kidneys conserve water during dehydration, and excrete excess water when sufficiently hydrated. During dehydration, blood flow declines and is only restored when the body has consumed plentiful amounts of water. However, kidney damage, sometimes permanent, may result from prolonged dehydration.
Heat stress nephropathy is now recognized as a cause of the chronic kidney disease that is seen globally among manual workers in sweltering climates associated with repeated episodes of dehydration. Additionally, summer weather is associated with an increased risk of developing kidney stones, which can cause severe pain and urinary obstruction. Adequate hydration prevents kidney stones.
Recognizing the SymptomsThe first symptom of dehydration is thirst, which should never be ignored. The brain activates the sensation of thirst and signals the kidneys to retain water upon the slightest detection of dehydration. Urine becomes concentrated and appears dark yellow or amber in color. Decreased urination throughout the day is also a sign of dehydration. Proper hydration quenches thirst and triggers the kidney to remove excess water, making urine appear clear to pale yellow. However, sugar-sweetened beverages for hydration should be avoided, as they may increase the risk for developing kidney damage, and regular consumption of these drinks is a risk factor for developing chronic kidney disease.
Tea colored urine may be indicative of kidney damage from profound dehydration. Other signs and symptoms of dehydration include increased heart rate or light-headedness upon standing from a seated position. Loss of consciousness may occur if symptoms are not recognized and dehydration is not treated promptly.
Facts About Chronic Kidney DiseaseChronic kidney disease, a long-term complication of recurrent dehydration, is usually diagnosed with a blood and/or urine test, since it’s symptoms are not readily distinguished from the symptoms of simple dehydration. Among those at greatest risk are people who work outside and have limited access to water for extended periods of time. And those living with diabetes are at even higher risk.
Alcohol must be avoided to quench thirst, as it blocks the kidneys from retaining water. Over-the-counter NSAIDs such as ibuprofen and naproxen are also prohibited during dehydration, as they can cause further kidney injury. Certain blood pressure medications, such as diuretics, angiotensin converting enzyme inhibitors (ACE inhibitors) and angiotensin II receptor blockers increase the risk of kidney injury in the setting of dehydration. In some cases, use of these medications may need to be adjusted during the summer, as directed by a nephrologist (kidney specialist).
Treatment of chronic kidney disease includes dietary and lifestyle modification, vitamins, minerals, and medications, which may stabilize kidney function or slow down the progressive decline in kidney function over time.
Keeping Your Kidneys HealthyThirst indicates dehydration, so prolonged thirst should be avoided. Water is the best choice for hydration and it is vital to consume enough until thirst is quenched. Increasing daily fluid intake above what the thirst sensation tells you does not offer any additional benefits. Most dehydration can be treated with increased oral fluid intake, but severe cases, especially those associated with strenuous exercise, raise the risk of kidney failure and require intravenous fluids in an emergency room.
So this summer, while you slather on the sunscreen, also try to keep your kidney health in mind. Of course, if you think you may have a problem, nephrologists, trained to diagnose and treat kidney disease, blood pressure, and electrolyte disorders, are here to help you.
Joshua Rein, DO, is an instructor of medicine (nephrology) at The Mount Sinai Hospital.