Thyroid UK
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Advice re T3 please


FREE THYROXINE 17.6 pmol/L 12.00 - 22.00

TOTAL THYROXINE(T4) 96.6 nmol/L 59.00 - 154.00

FREE T3 *2.54 pmol/L 3.10 - 6.80



I posted this last week and got a couple of replies that I am under medicated. I am going to my GP this afternoon and want to be 'armed' with information. She will no doubt just suggest I 'up' my Levothyroxine? If I ask her for T3, what would be the dose I need to take please?

I'm anxious about self medicating, but if I suggest I will buy T3 online and my GP advises the dose, what do you think she will say to know GPs don't like being questioned! Im thinking instead of going up 25 Levo, add 10 T3???

2 Replies

You really just need to increase your Levothyroxine at this stage by 25mcg and retest in 6 weeks. Further 25mcg dose increases until TSH is around one and FT4 towards top of range and FT3 at least half way in range

But you do also need to know if you have high thyroid antibodies. Have they been tested?

Also likely you have low vitamin D, folate, ferritin and B12

Request these are tested too

If you already know you have high antibodies then request coeliac blood test

If your vitamins are low then you won't make improvements on T3 or T4

Just seen your results from 7 days ago

There's no vitamin D test

Folate and B12 are on low side

You could try adding a good vitamin B complex and possibly daily sublingual B12 too

If you are taking vitamin B complex, or any supplements containing biotin, remember to stop these 3-5 days before any blood tests, as biotin can falsely affect test results

1 like


You are undermedicated to have TSH 3.94 and FT3 so far below range. Increasing Levothyroxine dose will raise FT4 and FT3 but probably won't raise FT3 sufficiently.

The goal of Levothyroxine is to restore the patient to euthyroid status. For most patients that will be when TSH is 0.2 - 1.0 with FT4 in the upper range. FT4 needs to be in the upper range in order that sufficient T3 is converted. Read Treatment Options in Email if you would like a copy of the Pulse article to show your GP.

Your GP may not be able to prescribe T3 without recommendation from a NHS endo. It may be worth asking for a referral because I think it is unlikely FT3 will respond sufficiently to 25-50mcg Levothyroxine dose increases.

Dose adjustments are usually in 25mcg increments for Levothyroxine or 6.25mcg - 10mcg T3.


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