Thyroid UK
87,631 members102,328 posts

Do I need supplementing with T3?

Just in case this post gets missed, I've started a new thread.

I had a blood test last week - I'm pushing my GP to potentially treat me in addition to my 100mg levithyroxine with some T3 as I still have a lot of symptoms - particularly lethargy, brain fuzz, low moods, inability to lose weight and constipation.

Here are the results:

Serum TSH level - 1.27 (0.38 - 5.5)

Serum Free T4 level - 14.0 (10.0 - 18.7)

Serum Free Triiodothytonine Level 4.1 (3.5 - 6.5)

Can anyone help me decipher these? On first look everything seems in range which leaves me at a loss. I'm starting to wonder whether it is all in my head :( But then I don't understand why I still have hypo symptoms.

Can anyone advise on next steps? I don't think my GP will do anything as my results are 'in range'

3 Replies


Your GP will probably be pleased with the results but the fact that you don't feel well shows you need an increase. Many of us feel better with a TSH 1 or below or even suppressed which some GP's would immediately reduce your dose.

You could ask your GP to reduce your dose of levo by 50mcg and add 10mcg of T3. If you need proof of this, email for a copy of the Pulse Online article by Dr Toft. Highlight question 6 for your GP to consider and you may be lucky and it may work to make you feel well.


Laura, it may be easier to persuade your GP to increase your Levothyroxine dose than prescribe T3. TSH around 1.0 is usually comfortable for people on meds but some need it lower 0.2-0.5 or even suppressed <0.04 to feel well. FT4 and FT3 should be in the top 75% of range ie your FT4 >16.52 and FT3 >5.75.

Dr A Toft, consultant physician and endocrinologist at the Royal Infirmary of Edinburgh, has recently written in Pulse Magazine, "The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.

In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l. Most patients will feel well in that circumstance.

But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.

This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."


Laura, just being 'in range' isn't good enough. The numbers need to be in the place that is best for you, and obviously they aren't at the moment.

I wouldn't say you have a problem converting but your T4 is too low at the moment to really be able to tell. If you don't have enough to convert then your T3 is obviously going to be low. Both your T4 and your T3 are Under mid-range at the moment, whereas most people need them to be up the top of the range to feel well. (Mid-range for T4 is 14.35 and for T3 is 5.00).

Try asking for an increase in your levo first, to get those levels up, and see how it goes. You might find you feel better just by doing that.

Hugs, Grey


You may also like...