Thyroid UK
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Baffled by new bloods following higher dose of levo


I need some help interpreting new set of blood test results. Doctor increased my dose from 150mg to 175mg levothyroxine as I was experiencing hypo symptoms. Just had my blood results back and I am baffled by the T3, unless the GP receptionist read it out wrong on the phone?!

Last three tests below to give history (total thyroidectomy due to follicular cancer)

April TSH 4.5 (0.4-5.5)

Oct TSH 4.7

Dec TSH 0.43

April T4 16.7 (11.5-22.7)

Oct T4 18.1

Dec T4 22.1

Oct T3 2.9 (3.5-6.5)

Dec T3 -3.3

I am pretty sure she said minus, I checked twice! Can anyone help to explain results and if I am finally on the right course?

Many thanks

3 Replies


I would ask for a printout of your Dec FT3 result to be sure but I think -3.3 must be an error. 3.3 would be an improvement on October's 2.9 but it is still below range.

December TSH and FT4 show you are adequately dosed but you are not converting sufficient T4 to T3. It is low FT3 which causes hypothyroid symptoms. Most people will need FT3 over halfway through range to feel well ie >5.0.

I am also thyroidless after thyCa and need Liothyronine (T3) in addition to Levothyroxine to deliver decent FT3 levels.


I think it must be an error, but yes as you say it is still under range. Looks like it's back to GP, even though he commented on results that they were satisfactory 🙄


Unfortunately, that's the usual responses from doctors. We have to read and learn for ourselves in order to resolve clinical symptoms.

My personal view is that sometone who has no thyroid gland whatsoever should have some T3 added to T4 (liothyronine (T3) - levothyroxine (T4). I had a thyroid gland but experienced difficulties when first prescribed levothyroxine.

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