A new study from Karolinska Institutet shows that global warming, combined with an aging population, could lead to a significant increase in people with severe electrolyte imbalances in the blood. The results are presented in the Journal of the American Society of Nephrology.
Researchers have discovered that the risk of severe hyponatremia, a dangerous electrolyte imbalance, increases significantly during the hottest days compared to the coldest periods. The study shows that women and the elderly are particularly vulnerable. For example, the risk of severe hyponatremia increased more than tenfold during heatwaves in people aged 80 years or older.
"Our results show that the risk of severe hyponatremia is stable between -10 and +15 degrees, but increases sharply at temperatures above 20 degrees," says the study's first author Issa Issa, PhD Student at the Department of Clinical Science and Education, Södersjukhuset , Karolinska Institutet and physician at Södersjukhuset.
By applying the results to a prognostic model that includes an aging population and the assumption of an increase in average temperature by one or two degrees by 2050, the researchers found that hospital admissions due to hyponatremia are expected to increase by 66% and 73%, respectively.
Hyponatremia occurs when sodium levels in the blood drop, which can lead to nausea, dizziness, muscle cramps, or even coma. Our bodies need sodium to maintain normal blood pressure, support nerve and muscle function, and regulate fluid balance in and around our cells.
"Knowledge about the risks of high temperatures may in the future motivate adequate information to the general population, but especially to the institutions that care for our elderly and frail patients; primary care, geriatrics, and perhaps most importantly, our nursing homes," says the study's last author Buster Mannheimer, senior lecturer at the Department of Clinical Science and Education, Södersjukhuset , Karolinska Institutet and senior physician at Södersjukhuset.
The study was conducted by linking millions of sodium measurements and data on the entire adult population of Stockholm to information on daily average temperatures over 14 years. During the period, more than 50,000 episodes of severe hyponatremia were noted.
As the next step in the research, the team plans to investigate how other environmental factors, such as air pollution, may affect the risk of electrolyte imbalances and fluid balance in humans.
This research has been funded by Department of Internal Medicine, Södersjukhuset, the Region Stockholm Drug and Therapeutics Committee and the Swedish Medical Association. No potential conflicts of interest have been reported.
Publication
"The Association of Outdoor Temperature with Severe Hyponatremia" , Issa Issa, Jakob Skov, Henrik Falhammar, Jonatan D Lindh, Buster Mannheimer, Journal of the American Society of Nephrology, online October 14, 2024, doi: 10.1681/ASN.0000000519
