Thyroid UK
82,813 members97,839 posts

low body temperature


I am taking my basal temp before getting out of bed in the morning and my readings are between 35.8 and 36.2. How low is this in terms of thyroid function? I am monitoring it to see what happens as i have just had my levo increased again for the 2nd time this year. My last TSH was 3.46. I was trying to tag this onto the back of a previous post but couldn't find how to do it- can anyone tell me how? thanks everyone :-)

8 Replies

I'd be interested in answers to this..I'm not on any medication for thyroid and my TSH is low but I'm always cold. I have taken basal body temperature sometimes and have had readings as low as yours (I think). I would need to check.


Yes, its funny isn't it, don't know how it works, I can be having a hot flush and my temp is still 36 or thereabouts. It would be interesting to hear what your temps are.


Hi Sue - I have periods where I take y basal temps. I'm not very good with Celcius readings but I remember some being 35 but usually over 36. I sweat a lot but I feel cold not hot, it is bizarre!

1 like

Sue_b, you can update your previous thread by adding a reply to it but it's better to post a new question because its visible to everyone whereas updates only get seen on Newsfeed.

Temperature may rise when increasing dose and can be a sign of overmedication if it goes too high but if it has been low a long time it doesn't always recover even when optimally dosed.

TSH 3.46 is too high for someone on medication and means you were undermedicated. The goal of Levothyroxine is to restore the patient to euthyroid status and for most people this will be when TSH is around 1.0 and FT4 is in, or towards, the top quadrant of range.

1 like

I hope you don't mind me asking a question on the back of the main one, but I've never understood why euthyroid status for those on medication is different from those who aren't on medication but have the same results.

In my case, (I'm considered to have values within the 'normal' range so considered euthyroid), TSH is usually over 3 (0.35-6) and FT4 and FT3 in the lowest quadrant.

If euthryoid is 1.0 for those on medication, why isn't it for those not on medication? A well-known medical practitioner who treats ME patients asks the same question as the majority of her patients have the same profile as me (who, incidentally, was diagnosed with ME thirty years ago) and she is convinced that the thyroid is implicated in ME/CFS, as well as mitochondrial malfunction.

Are there any peer-reviewed articles dealing with this anomaly (if it considered to be so)?

Thanks, Ann


Ann, I would hazard that you aren't feeling well with TSH 3.0 and FT4 and FT3 in the lower quadrant.

TSH rises in response to low T4 and T3 and stimulates the thyroid to produce more hormone. People diagnosed aren't able to produce sufficient hormone so have Levothyroxine to replace low hormone.

TSH 1.0 of people on Levothyroxine will usually ensure sufficient T4 for conversion to T3. There are rather a lot of GPs and some endos who think mid-range TSH is adequate. The ranges are statistical norms based on population levels so aren't individual anyway. I don't think that people with thyroid dysfunction are even screened out from the samples used to determine the ranges.

There was a US Navy study which showed TSH 0.5-1.7 seems to be the euthyroid range for healthy people. The study found certain ethnic groups are prone to hyperthyroidism rather than hypothyroidism.

TSH >2 is an indication thyroid is struggling and some practitioners think >1.5 is a better indication. The ATA lowered the top of range to 3.0 in 2006 but 5.0 is still widely used across the USA. I think UK is the only country which doesn't diagnose overt hypothyroidism until TSH >10 and considers >5 <10 to be subclinical. TSH alone isn't a good guide, it's a pituititary hormone, and when thyroid hormone, FT4 and FT3, aren't tested diagnoses of secondary and tertiary hypothyroidism will always be missed.

I think the ME practitioner is right. Prior to the mid 70s hypothyroid diagnosis was made on clinical symptoms. Since the advent of TSH, FT4 and FT3 and the 'normal' ranges diagnoses of ME/CFS/Fibromyalgia have appeared.

I'm still reading through this article which discusses medical and environmental effects on psychiatric illness. Thyroid and cortisol are discussed. The author isn't in favour of reliance on blood tests only to excluded a diagnosis.


Yes it's an anomaly - GPs are advised not to treat Hypo from just signs/symptoms but from the TSH (an unreliable pituitary test anyway).

Once you have hormone replacement it tends to be a lifelong treatment, not temporary.

I too was 'sub-clinical' for years (even after a partialT op) with a TSH over 5 - they won't generally diagnose 'til it goes above 10. So many folk continue to suffer symptoms (which are ignored or misdiagnosed as something else, CFS in my case).

Even when diagnosed some GPs think that merely being in range is fine - despite continuing symptoms. They are very worried about 'overdosing' so most folk remain underdosed. J :D

a previous post with link to RCP advice


Thanks Clutter :-)


You may also like...