Thursday 5 December 2019

Heatwave linked to higher risk of stroke

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Lynne Kelleher

The incidence of a condition which can increase rates of stroke and heart attack more than doubled among older people during a recent heatwave.

Hypernatraemia, the term for high levels of sodium in the blood, is usually brought on by severe dehydration.

A new study has shown for the first time that the rate of the potentially fatal blood abnormality can rise by 250pc during a heatwave in a temperate climate.

Blood tests taken from Irish people aged over 65 during the 10-day heatwave from June 24 to July 3, 2018, when temperatures hit an average 27C, were compared to tests from the same period the previous year when it was around 10C cooler.

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Prof Eamon Mulkerrin, senior author of the paper published in QJM: An International Journal of Medicine, said the findings have particular relevance as the likelihood of heatwaves is greatly enhanced by climate change.

Hypernatraemia occurs when salt concentration of the blood rises usually due to dehydration because of water depletion.

"Blood is concentrated, more prone to clotting and therefore at-risk people can develop clots, strokes," explained the professor, from the Department of Geriatric Medicine at University Hospital Galway. It can develop in as little as one to two days in people with low fluid intake or excessive fluid loss through sweating.

The study examined nearly 3,500 blood samples from community and hospital patients; natraemia was present in 3.6pc of samples collected during the heatwave, compared with 1.4pc in the control period the previous year.

The study, carried out in University Hospital Galway and NUI Galway, was co-authored by Prof Mulkerrin, Dr Michelle Brennan, Dr Paula O'Shea and Orla Murray. Prof Mulkerrin said it shows that the abnormality increases greatly during hot weather, even in a mild temperate climate in the west of Ireland.

"There are reports of up to 60pc increased mortality with hypernatraemia, especially in older people who are vulnerable and have reduced reserves compared with a younger population," he added.

Sunday Independent

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