Heat Exposure and Hormones
LRF OCEHL Director, Professor Fadil Hannan, has led the publication of a collaborative article in Nature Reviews Endocrinology highlighting the urgent necessity for expanded research into the impact of heat exposure on the endocrine system.
This groundbreaking publication, produced by endocrinologists and researchers from the LRF OCEHL, the London School of Hygiene & Tropical Medicine, the William Harvey Research Institute at Queen Mary University London, and the National University of Singapore, emphasises the critical need for further research into the effects of heat exposure on the endocrine system.
THE ROLE OF HORMONES IN ENVIRONMENTAL ADAPTATION
Hormones play a role in nearly all biological functions, yet the influence of environmental factors on hormone release and action is not well characterised. With climate change increasing seasonal temperatures and causing more frequent heatwaves, understanding these effects has become more crucial than ever.
Hormones influence how we adapt to changes in environmental temperature by controlling processes such as conservation of body water, sweating, and heat generation from cell metabolism. A review of studies published from the 1940s onwards indicates that heat exposure affects hormones involved in processes ranging from the stress response, blood glucose control, fertility, and breast milk production. However, many of these studies involved short-term heat exposure in non-human animal models or in healthy human volunteers such as military recruits.
THE KNOWLEDGE GAP: LONG-TERM HEAT EXPOSURE AND ENDOCRINE CONDITIONS
Our review highlights the gap in evidence regarding the impact of sustained heat exposure on the endocrine system, which is particularly relevant to the increasing numbers of people living with endocrine conditions such as diabetes mellitus or thyroid disorders, who may have limited tolerance to higher temperatures. Heatwaves increase the risk of hospitalisation for these patients, which also increases the burden of heat on the health system.
Lead author, Professor Fadil Hannan, LRF OCEHL Director, stated, “We know very little about whether increased heat exposure due to climate change could affect endocrine health. We require research involving both the endocrine and global health research communities to assess the impact of rising temperatures and heatwaves on endocrine patients. This is particularly important for patients living in hot climates, who may have inadequate access to cooled environments. A better understanding of these effects will enable interventions to be developed for endocrine patients most at risk from heat extremes.”
HORMONAL DISORDERS AND TEMPERATURE REGULATION CHALLENGES
Certain hormonal disorders can disrupt the body's ability to regulate temperature, making it harder to cool down and increasing the risk of heat-related illnesses. Co-author, Professor Jason Lee, at the National University of Singapore, adds, “As the world grapples with the escalating threats of climate change, unravelling the intricate relationships between heat exposure, endocrine function, and human health is not only a scientific imperative but a moral obligation to protect the vulnerable and ensure the well-being of generations to come.”
The management of heat risks is becoming increasingly important and this review highlights the need to educate health professionals about environmental hazards. Co-author, Associate Professor Sari Kovats at the NIHR Health Protection Research Unit in Environmental Change and Health at LSHTM, adds, “We need to do better to manage heat risks in patients with diabetes and other endocrine disorders”.
Fig. 1: Possible involvement of hormones in thermoregulatory adaptation to heat.
CLIMATE CHANGE, HEATWAVES, AND HEALTH: THE URGENT NEED FOR RESEARCH
Heatwaves are increasing in frequency and severity with major impacts on health. Co-author, Professor Rajesh Thakker from the University of Oxford and Queen Mary’s William Harvey Research Institute states “Climate change with increasing heat exposure are major global challenges confronting us, yet we know little about their effects on health, and identifying these gaps in our knowledge is important for planning strategies and future research for the benefit of humankind”.
TO READ THE ARTICLE IN FULL
Endocrine effects of heat exposure and relevance to climate change
by Fadil Hannan, Melvin Leow, Jason Lee, Sari Kovats, Taha Elajnaf, Stephen Kennedy, and Rajesh Thakker