Thyroid UK
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T4 & T3 levels and whether I am not converting to T3

Hello Everyone.

I am looking for a bit of advice. I have been on T4 Levothyroxine for around 5 years now. My current dose is 125mcg. I have really bad symptoms of hair loss, memory loss, cold hands, dry skin, restless legs.

I recently had blood tests taken and the results were: TSH 4.25 ( 0.55-4.78) T4 18 (10-25) T3 4.9 (4-7).

I have seen a lot of posts regarding problems with converting T4 to T3 and whether the level I am at would be giving any of these symptoms and whether I would require to take T3 at all, and if so, what dose and how much to reduce T4 by?

I have been to my GP in Scotland and they are not willing to listen to anything even though I bring a huge bag of hair with me to the appointment.

Looking for any advice from people with a similar story.

Thanks in advance for any help!

5 Replies

lynnie0123 For thyroid hormone to be able to work properly we need optimal levels of vitamins and minerals, and it's best to check those before going down the T3 route.

Have you had the following tested, if so post the results with reference ranges for comment:

Vit D




Your results show that you appear to be undermedicated, with TSH far too high in it's range, FT4 just half way and FT3 very low. The aim of a treated hypo patient generally is for TSH to be 1 or below or wherever it is needed for FT4 and FT3 to be in the upper part of their respective reference ranges.

From ThyroidUK's main website > About the Thyroid > Hypothyroidism - Treatment Options


According to the BMA's booklet, "Understanding Thyroid Disorders", many people do not feel well unless their levels are at the bottom of the TSH range or below and at the top of the FT4 range or a little above.

Dr Toft states 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)."


Dr Toft is past president of The British Thyroid Association and leading endocrinologist.

If you would like a copy of the article then email and you can print it off to discuss with your GP, this is question 6 (I think).

1 like

Thank you for your reply! I will try and get levels checked for vitamins etc. Lynne


You also need to know if you have high Thyroid antibodies. There are two sorts TPO & TG - BOTH need checking. NHS rarely tests for both

If one or both are high this means the cause of thyroid issue is Hashimotos (most common reason in U.K. for bejng hypo)

If you have Hashimotos then very many of us find huge benefits from going on strictly gluten free diet

Vitamin levels as seasidesusie says are also extremely important

Private tests available via Thyroid Uk if GP won't - Blue Horizon or Medichecks- £99

See also websites

The Thyroid Pharmacist

Amy Myers

Chris Kresser


Thank you for your reply! Most appreciated!


Hi Lynnie, yes, your conversion could be better but you could also increase your dose to 150 and see what happens. If you can acquire some T3, you could just add to your 125 dose. A partial dose of one half of a 25 ug as Uni-Pharma supplies might give you some relief.


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