Thyroid UK
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Different dose levo summer/winter

Hi all,

I read a lot about the thyroid and I have read a couple of times that the dose of levothyroxine in the summer is often different than in the winter. I can't figure out why this is? It has to do with the temperature I guess but what makes the body ask for more/less hormone just because it's warmer or colder?

And could you tell me your experience in this, do you wait till you feel bad and get a blood test or do you just adjust the dose?


4 Replies

If we are hypo, our body works artificially on thyroid hormones. This is an excerpt:

'You probably already know that a variety of factors influence your metabolism, including what you eat, how frequently you eat, how often and what types of exercises you do, and how well you sleep. In addition to these well-known factors, temperature also plays a role in your metabolism.

Metabolism is the chemical process your body goes through to convert the food you eat into energy for every part of your body to function. The more energy your body needs to maintain basic bodily functions, the higher your metabolism; conversely, the less energy your body needs, the lower your metabolism. Essentially, your metabolic rate is the amount of energy (calories) your body burns to maintain itself – think about the energy your body needs to breathe, think, talk, walk, sit, digest food, keep your heart beating, circulate your blood, and maintain your normal body temperature.

Your body is constantly regulating its core temperature to around 98.6 degrees Fahrenheit (37 degrees Celsius). When your climate heavily differs from this temperature, due to cold or heat, your body extends more energy by shivering to heat up or sweating to cool down – all in an effort to maintain its preferred temperature.'

So, because our body doesn't function normally re metabolism if hypo, sometimes we have to adjust dose slightly if the weather is too hot or too cold'.

You don't particularly feel bad but you may feel too cold or too hot. That's why it's good to take your temp as sometimes we do feel quite hot but temp might be normal/or slightly below.


Thanks Shaws, that makes sense! I'm just a bit worried now, I'm still in the process of finding the right dose for me and scared that if I will finally find it that I will have to change it again because of the weather.

But as it understand it correct it isn't as serious as going hyper/hypo but it's just a little bit off?


Flower, TSH is higher in autumn/winter than spring/summer and some people can feel slightly overstimulated during the warmer weather and find a small dose reduction helpful. If you feel too hot, too sweaty and perhaps a bit jittery/anxious then a reduction of 12.5mcg to 25mcg may be helpful. Not everyone notices any difference between winter/summer so it may not affect you. It isn't something to worry about, just to bear it in mind if you do feel overstimulated and reduce dose accordingly and raise it again if you feel a bit hypo when the weather cools.

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Personally I think its all about sunshine levels, less in winter.


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