Why do menopausal women get hot flushes?

It’s still not completely clear why women suffer from hot flushes with the menopausal transition and afterwards. However, researchers are gaining a better understanding of why these symptoms occur.

It seems we all have an internal “thermostat”. Our bodies like to stay within a certain core body temperature. When our core body temperature rises or falls above or below this range (0.4C in women who aren’t having hot flushes) our bodies activate mechanisms to correct this. If our core body temperatures rise too much, for example, the tiny capillaries in our face, chest and arms will suddenly dilate, causing a rush of blood to the surface and, consequently, heat dissipation. This is part of the reason we get a red face and sweat during aerobic exercise – we’re trying to cool down.

Researchers think that something about the menopausal transition causes a resetting of this internal thermostat. It seems to be related to the drop in oestrogen, a key female hormone, and subsequently, a drop in serotonin and rise in noradrenaline. Serotonin is a “happy hormone” – a neurotransmitter, or chemical messenger, that makes us feel happy and also plays a part in pain transmission. Noradrenaline is a hormone that is released when we feel anxious or under stress – it raises our blood pressure and causes the “fight or flight” syndrome. Researchers now know that these two chemical messengers are involved in the resetting of our internal thermostat after a drop in oestrogen with the menopause. The threshold for sweating decreases, so that a tiny rise in core body temperature causes the sweating and flushing mechanism in an attempt to “cool down”. Why this doesn’t happen in all women is still a bit of a mystery, but much work is being done in understanding risk factors for experiencing hot flushes.

Half of the time, hot flushes are triggered by something external such as drinking a hot beverage, having caffeine or alcohol, exercise, feeling stressed, a hot day etc. The other half of the time, hot flushes appear spontaneously, for no apparent reason.

So the next time you start fanning yourself during a meeting and wiping the sweat off, just explain to your colleagues that your “thermostat is busted” and hopefully will be fixed in due course!

Photo: By Kilom691 (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons