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Thyroid UK
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Low basal body temperature

I was diagnosed hypo due to high antibodies in January andam now on 50mg levo (recently increased from 25), I have always suffered from feeling cold but only the last few weeks started measuring my basal body temp first thing in morning (for ovulation tracking) and then got curious and have been checking it throughout the day.

I know low basal temp is a symptom of hypo but I was wondering if there are any points when it should become a concern. Mine if mostly 35 or 35.1, reguarly just going under at arounf 34.8 and never going over 36. I read that 35 is considered hypothermia on the NHS website, if I am reguarly (daily) going under 35 is this ok or is it something I should rasie with my doctor?

I am already being made to feel like I am raising every small concern (unfortunately as I gather many of us are!) so if there is no concern I will just carry on with layering up :)

Many thanks!

11 Replies

Yes that is low and yes you really should raise it with your gp. Get them to take your body temperature. What are your latest TSH T4 results? How are you feeling?


Hi Poppy, thanks for the reply. My last one 2 weeks ago (which is when the increased me to 50mg) was 2.9 (going down from 5.6 in Jan when they put me on 25mg). My antibodies rose from 260 to 1300 but from what I gather this isnt actually anything directly to do with hypo/cause symptoms, it is the high anytibodies that cause the hypo, hope I have understood this right! They have agreed they want to get TSH a little lower so at least are not going on the 'normal range' basis wich I am thankful for! I was feeling fine the last month or so but have been off work all this week (I love my job so don't take time off unless feel really have too!) feeling literally like someone has zapped all the energy out of me since Sunday morning), I slept from 10.30pm last night right through to 1pm today and still felt shattered! Feel cold but this is so normal for me!


Have you had any other tests? Vit D, Ferritin/iron, B12. It could be your adrenals feeling stressed, it could be that you are still under medicated, it could be as simple as you have a virus right now and feeling pants.


No other tests, I am due to have my TSH and antibodies done again on 16th May and at that point he said he will consider sending my to a private endo if not happy (as I have cover through work), no mention of an endo before I mentioned this! Maybe a virus, I will give it the rest of this week and if still not right try (being the key word at my surgery!) and get an appointment Monday. Will raise the low temps with him anyway as I am wondering about longer term issues if my body is constantly going into a level they would consider hypothermia, am guessing that cant be good on the old organs.

Thanks Poppy, think I was just looking for some re-assurances that I am not worrying about nothing so I dont raise something unecessarily! :)


The biggest thing would be to get other tests done. Vit D and iron are vital and typically seem to be low in those with thyroid problems. You need to consider taking some supplements like B12 and other B vitamins to support your adrenals which will have come under pressure with your thyroid being underactive. You say you are taking your temperature to track ovulation. Are you trying to get pregnant?


I have recently starting taking a few supplements which include vit B but I think I will look at getting a higher dose vit B only form. Yes, I have been for over a year now but only the last few weeks started looking at temps. Is adrenal fatigue something they can test for or do the results of the vitamin tests suggest there may be a problem?


They can do a cortisol test for the adrenals which is not overly helpful as it is very open to interpretation. I think on here there are some saliva tests that can tell you how your adrenals are performing but I haven't done one. I take T3 now and have been taking a dose just before bed to help with mine and that has been enough. I also take lots of supplements.

You may find that getting your thyroid stable will help with conception. Having said that I was an undiagnosed underactive thyroid and I did get pregnant (miscarried twice). I now have a very healthy 5 year old. Just be careful with certain vitamins like Vit A, look into it or ask on here.

Do you have a regular cycle? Thyroid suffers often do not along with a heavy period. Have you noticed any change in your temperatures? I did all the temperature stuff and mine was normal before, did the usual slight up and down for ovulation. It only plummeted to the early 35's once on T4. I did not make the connection at all at the time. You are probably still quite underdosed.

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I have just had a look at the home testing via the link on here, may look into this on payday! They have said it should help, when I said we had been trying a year they said to scrap it and start from now as TSH was probably causing infertility. They have said give it 6 months and then if nothing they will look into it more...just have to be patient I guess...hard when you want something so much!

I was regular when on pill, came off over a year ago, started off regular at 35 days for about 6 months but then went to 40, then 45 now I have missed a period and not had one since 1st Feb (although def not pregnant) so if anything since being on the levo they have got worse! My temps seem a bit all over the place really as in going from between 34.8 to 35.6 each morning so if I was to go by the you ovulate when it goes up a few .'s of a degree then I have ovulated a few times in the last 2 weeks since started it!

Hopefully in 6 weeks when I have my re-tests I can re-raise my concerns/ask for vitamin tests etc and they will do some further investigations! Thanks Poppy!


Tell me about it. My husband, we discovered, had a zero sperm count, long story. But after 2 paid for privately operations we got back enough of a count, with the help of some major vitamin therapy, for me to conceive. I miscarried twice and I think it was the second miscarriage that really triggered off the thyroid condition (although I can see in 1995 I had it but they ignored it). Needless to say our little girl is a miracle baby who brings us so much joy and comfort.

I would personally not wait the 6 weeks, I would call and ask them to do these blood tests now so you can see where you are at. In 6 weeks time you will have the tests and then wait for another appointment for the results before you could even consider treatment. Its a long time in the all consuming fertility.

Have you used the ovulation predictors?


Hi Poppy,

I wish that my GP would work with me to get temp up! the other day when I told her that my

temp was very low, she said that it is better that your body worked on lower temps you don't wear your body out so quick!! not everyone has a temp of 37. so it is hard to get through to them/they win.

Regards wakeham


That is rubbish and your GP is talking through their wotsits! I agree that not everyone has a temp of 37 we should all be somewhere around that and it should also be what is normal for you. I was always a dead on normal to the point of a degree, standing family joke I could test to see if a thermometer was accurate. Bad Endo wouldn't even take my temperature or acknowledge I even said anything about it.

Much lower temperatures put you into the hypothermia range and that is generally note considered good. So why is normal considered fine within the range of thyroid and not for temperatures? If your temp is up 2 degrees they would be concerned, why not 2 degrees lower then. Lazy doctoring.


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