Global warming expected to increase health burden of hyponatremia

Global warming is likely to increase the number of people requiring hospitalization due to extremely low blood sodium levels, a condition known as hyponatremia. A new study from the Karolinska Institutet in Sweden predicts that a temperature increase of 2 degrees Celsius would increase the burden of hyponatremia on hospitals by almost 14%. The findings are published in the Journal of Clinical Endocrinology and Metabolism.

“Our study is the first to provide precise estimates of how temperature influences the risk of hyponatremia, findings that could be used to inform health care planning to adapt to climate change,” says Buster Mannheimer. , Assistant Lecturer in the Department of Clinical Sciences and Education. , Södersjukhuset, Karolinska Institutet and the first author of the study.

Climate change is expected to trigger an increase in average global temperatures over the coming decades, leading to myriad heat-related consequences for human health. One of these is hyponatremia, which can result from various diseases such as heart, kidney, and liver failure, as well as excessive sweating or fluid intake that dilutes the sodium concentration in the blood. .

Our bodies need sodium to maintain normal blood pressure, support nerve and muscle function, and regulate water balance in and around our cells. If blood sodium levels drop, it can lead to nausea, dizziness, muscle cramps, seizures, and even coma.

It is well known that cases of hyponatremia increase during the summer months. Yet data on temperature thresholds above which risks amplify are lacking, complicating clinical planning and predictions of health burden in future climate scenarios.

Women and the elderly at risk

In the current study, the researchers linked data on Sweden’s entire adult population to information on average 24-hour temperatures over a nine-year period. During this period, more than 11,000 people were hospitalized with a primary diagnosis of hyponatremia, most of whom were women with a median age of 76 years. Average daily temperatures ranged from -10 to 26 degrees Celsius.

The researchers found an almost tenfold higher risk of hospitalization due to hyponatremia on the hottest days compared to the cooler times. Women and the elderly were at greatest risk, with people aged 80 or older 15 times more likely to be hospitalized for hyponatremia during heat waves. The incidence of hyponatremia was largely stable at -10 to 10 degrees Celsius, but increased rapidly at temperatures above 15.

When the researchers applied the data to a prognostic model predicting global warming of 1 or 2 degrees Celsius, consistent with IPCC climate projections for 2050, they found that hospital admissions due to hyponatremia could increase by 6 .3% and 13.9%, respectively. .

Increased health burden

“We think these estimates are quite conservative because we didn’t take into account secondary diagnoses of hyponatremia, extreme weather events, or an aging population,” says Jonatan Lindh, associate professor in the Department of Laboratory Medicine. , Karolinska Institutet, and co-last author of the study. “Without adaptation measures, this suggests that over the coming decades, rising global temperatures alone will increase the burden of hyponatremia on health systems.”

It should be noted that Sweden is in the continental climatic zone, with buildings suitable mainly for cold temperatures. Therefore, the thresholds observed in this study may be representative only of cold temperate regions.

The study was partially funded by Cebix Incorporated. Two authors report previous consultancy fees from Otsuka Pharma Scandinavia AB, outside of the submitted work.

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Materials provided by Karolinska Institute. Note: Content may be edited for style and length.

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