Thyroid UK
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Thyroid Results - What do they Mean?

First time on site. Have had an under active thyroid for many years and although I'm on 125mg of levothyroxine per day I never feel well. I'm overweight although I'm continually on a diet, I'm always tired and I'm prone to infections. Recently I asked for a print out of my results (which I've never had before) and was told that I was normal. I just want to check if this is so. Here are my results:

Serum free T4 Level 17.5 pmol/L (12-22)

Serum TSH Level 2.14 mU/L (0.27-4.2)

Serum free T3 Level 4.1 pmol/L (3.1-6,8)

Could someone please explain these to me.

Thanks Jennifer

4 Replies

Your slightly under medicated

The aim of thyroid replacement hormone (Levothyroxine) is to bring TSH down to around one and FT4 towards top of range and FT3 at least half way in range

Your FT3 is low - either because dose is not high enough or you are a poor converter of T4 to T3. Very common if vitamins are low or if you have Hashimoto's

All thyroid tests should be done as early as possible in morning and fasting and don't take Levo in the 24 hours prior to test, delay and take straight after. This gives highest TSH, lowest FT4 and most consistent results

Is this how you did the test?

Link about antibodies

Link about thyroid blood tests

Print this list of symptoms off, tick all that apply and take to GP

It's very common to have low vitamin levels when hypo, especially if you have Hashimoto's

Ask GP to test vitamin D, folate, ferritin and B12

Post results and ranges when you get them on new post

Hashimoto's is diagnosed by high thyroid antibodies. Have you ever had antibodies tested? If not ask that they are

See if you can get thyroid antibodies and vitamin testing from GP.

Private tests are available - £28 postal kit

Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.

See Box 1. Towards end of article

Some possible causes of persistent symptoms in euthyroid patients on L-T4

You will see low vitamin D, folate, ferritin and B12 listed

1 like

Thank you. Will follow your advice.


Stop dieting! It won't make you lose weight while your FT3 is below mid-range, but will affect your conversion so that your FT3 stays below mid-range. You need calories to convert. You also need optimal nutrients, and it's unlikely you'll have them if you're always on a diet. Low-calorie diets are not recommended - especially not for hypos.

1 like

Thanks for the advice.


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