Prolonged heat waves and the sweltering summer days that accompany climate change can be hazardous for human health, leading to conditions such as heat stroke and even causing permanent organ damage or death if not treated quickly.
Faculty at the University of Colorado School of Medicine and Colorado School of Public Health point to the kidneys as particularly vulnerable to a warming world.
“Climate change should be of special concern for the nephrologist, as the kidney has a critical role in protecting the host from dehydration, but it is also a favorite target of heat stress and dehydration,” CU researchers wrote in the January edition of Nephrology Dialysis Transplantation.
“We used to focus on concerns about infectious diseases as a result of climate change, but we’re now moving into a world in which we’re seeing a shift in the amount and severity of chronic illnesses that also include non-communicable diseases, including kidney disease,” says Lee Newman, MD, distinguished professor of medicine and environmental and occupational health, and director of the Center for Health, Work & Environment on the CU Anschutz Medical Campus.
While extreme heat can cause heat stroke, severe electrolyte disturbance, and acute and chronic kidney disease (CKD), lesser levels of heat stress may also affect the body.
Kidney health and heat
The kidneys are metabolically very active, explains Sarah Young, MD, associate professor of clinical practice in the Department of Medicine, Division of Renal Diseases and Hypertension.
“They actually require a quarter of your blood flow, and they’re also an organ that will sacrifice their own well-being in order to preserve blood flow to other places in the body, like the brain,” she says. “So if you get severely dehydrated, your kidneys are going to shut down and stop working in order to supply blood to the rest of the body.”
Damaged kidneys can lead to more adverse health effects across the body, too. CKD, a condition in which the kidneys are damaged and can’t properly filter blood, can lead to heart disease, stroke, and greater susceptibility to climate change-related illnesses.
“The kidneys are a smart organ, and they will compensate when able. However, extreme weather events test the kidneys compensation mechanisms,” Young says. “This is especially true in vulnerable populations, such as the elderly, whose ability to adapt may be compromised.”
Adaption in a warming world
As the climate continues to heat up — climate scientists say July was the hottest month on record — Newman and Young say more people will become vulnerable to kidney damage and the health issues that follow.
Newman has focused heavily on workers who experience extreme heat. In 2016, he began working with Grupo Pantaleon, a multinational agriculture company based in Guatemala, that reported relatively high rates of employees with kidney disease.
“In an ideal world, we wouldn’t have anybody developing chronic kidney disease as a result of exposure to heat. Heat and dehydration paired with exposures to kidney toxins is, quite frankly, causing an epidemic,” Newman says. “But, we're also making inroads. We now have several NIH-funded grants to continue our work in Latin America, and we’re starting to see results.”
Kidney disease rates at the company are now down to less than 2% of workers at the end of the season, Newman says. It used to be above 6%. Newman and his team have helped the company and its employees adapt to a hotter climate, changing policies and closely monitoring the workers’ health and safety.
In all places around the world, Young says vulnerability will increasingly be dependent on the ability to adapt, and factors, such as socio-economic status, can also play a role, just as age and health can.
“There's a whole population that doesn't have air conditioning and can't get to a cooling center or who live in urban area where it's going to be a lot hotter with no green spaces,” she says. “They are going to be more vulnerable than others.”
