SINGAPORE: A multi-disciplinary team of researchers from the Yong Loo Lin School of Medicine at the National University of Singapore (NUS Medicine), in collaboration with the University of Oxford, the London School of Hygiene & Tropical Medicine, and the William Harvey Research Institute (WHRI) at Queen Mary University of London, has called for urgent research into the effects of heat exposure on the endocrine system.
With climate change driving higher seasonal temperatures and more frequent heatwaves, understanding how extreme heat impacts the body’s functions has become a critical priority.
The team’s recent review highlights a significant gap in existing evidence, particularly concerning the long-term effects of sustained heat exposure on the endocrine system. The review draws attention to studies published as far back as the 1940s that focus on the impact of short-term heat exposure in pre-clinical models.
These studies have examined the influence of heat on hormones involved in essential processes such as the stress response, blood glucose regulation, fertility, and breast milk production. However, more comprehensive research is needed to fully understand these effects over prolonged periods of exposure.
Some data suggest that heat exposure may negatively affect foetal endocrine development, although the impact on children going through puberty remains unclear. Additionally, rising ambient temperatures have been linked to a decrease in ovarian follicles, which could result in reduced fertility.
Several areas of concern have been identified. Pregnant women exposed to high temperatures over extended periods may face an increased risk of maternal complications, such as gestational diabetes mellitus, as well as higher risks of preterm birth, stillbirth, and low birthweight.
During menopause, women experience neuronal and hormonal changes that impair thermoregulation, leading to hot flushes that could be exacerbated by rising temperatures.
The review also underscores the potential consequences for patients with thyroid disorders and diabetes mellitus. Thyroid disorders are linked to impaired thermoregulation, but the broader effects of heat exposure on populations with these conditions are still not well understood.
For patients with diabetes mellitus, there is a heightened susceptibility to water loss and dehydration, along with reduced skin blood flow and impaired heat dissipation. Heat extremes also pose an increased risk of cardiovascular events in this population due to the combination of these factors.
The review, published in *Nature Reviews Endocrinology*, emphasizes the need for further research to fill these critical gaps in knowledge, particularly as the world continues to grapple with the consequences of climate change.
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