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Published on: November 21, 2017
Physiology of hot flashes
1Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, Michigan 48201, USA. aa2613@wayne.edu
Summary
Hot flashes in menopause are linked to a narrowed thermoneutral zone, not core body temperature changes. This reduced zone, along with increased sympathetic activity, triggers these common menopausal symptoms.
Area of Science:
- Reproductive Endocrinology
- Thermoregulation Physiology
Background:
- Hot flashes are a prevalent symptom of menopause, characterized by heat-dissipation responses like sweating and vasodilation.
- While associated with estrogen withdrawal, estrogen levels alone do not differentiate between symptomatic and asymptomatic women.
Purpose of the Study:
- To investigate the thermoregulatory mechanisms underlying hot flashes.
- To explore the role of the thermoneutral zone and sympathetic activation in triggering menopausal hot flashes.
Main Methods:
- Utilized a telemetry pill to measure core body temperature changes.
- Assessed the thermoneutral zone in symptomatic and asymptomatic women.
- Examined central sympathetic activation levels.
Main Results:
- Symptomatic women exhibited a virtually nonexistent thermoneutral zone, unlike asymptomatic women with a normal zone (approx. 0.4°C).
- Elevated central sympathetic activation was observed in symptomatic women.
- Small temperature increases within a reduced thermoneutral zone appear to trigger hot flashes.
Conclusions:
- Hot flashes are triggered by minor temperature fluctuations within a significantly narrowed thermoneutral zone in symptomatic women.
- Reduced thermoneutral zone and increased sympathetic activity are key factors in hot flash generation.
- Clonidine may alleviate hot flashes by reducing sympathetic activation and widening the thermoneutral zone.
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