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Thyroid UK
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Where has the T4 gone?

I took advice from the forum late last year and ordered medicheck tests which I posted in December. After reading lots of very helpful advice and links in response, I went to see my GP to ask if he thought I may have a conversion problem. He was not convinced but ordered a repeat Thyroid test, this time to include T3 (hurrah!). I will now post some historic test results to give you context for my question:

date TSH T4 T3

2012 0.1 18.1 not tested

2013 0.08 18 "

2016 0.1 18.3 "

08/17 0.08 18.5 "

12/17 0.159 22.1 4.36 private test

01/18 0.13 13.7 4.7

The private test found TPO antibodies too, but that was not retested.

Even if I ignore the private test, that seems quite a drop between August and January, and looks out of place on the trend, doesn't it? What could cause this? And should I still pursue the conversion question?

I can think of a couple of changes since August: my ferritin level increased from 33 to 63, plus on advice from the forum I started taking vit D daily (although my GP thought this unnecessary as many people 'do well enough on that level' (35))

I have not gone back to him to follow up this latest result as I need to be well-prepared!!

Many thanks in anticipation.

9 Replies

Sorry for the layout of the results: I had them all nicely spaced and aligned, but it all went to pot when I hit POST!


I'm sorry, but not only is it very difficult to read your results, you haven't put any ranges, so they are meaningless.

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I feared as such! Thank you Grey Goose, will try again.



Best format on here is :

Date ---

TSH --- (range)

FT4 --- (range)

FT3 --- (range)

Date --- etc.

That will stay readable. :)


I have reposted the test results, Grey Goose. :)


OK here goes:

July 2016

TSH 0.10 mu/L [0.3-5.0]

FT4 18.3 pmol/L [7.0-20.0]

Aug 2017

TSH 0.08 mu/L [0.3-5.0]

FT4 18.5 pmol/L [7.0-20.0]

Dec 2017 (private test)

TSH 0.159 mIu/L [0,27-4.2]

FT4 22.1 pmol/L [12.0-22.0]

FT3 4.36 pmol/L [3.1-6.8]

Jan 2018

TSH 0.13 mu/L [0.3-5.0]

FT4 13.7 pmol/L [7.0-20.0]

FT3 4.7 pmo/L [3.5-5.8]

The previous years I have left off were all about the same as the July 2016 values.

Hope that is easier to read! Thank you.


Assuming you did all tests under same conditions and time of day?

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

Because you have improved your vitamin levels you are able to utilise your thyroid hormones better

You are ready for dose increase.

But GP probably won't agree as a TSH is low


The last 3 tests at least were all done as you say, Slow Dragon. :)


I did wonder if the iron and D3 I have been taking would have made a difference, but had only been taking them for 3 weeks when the test was done. However, I still feel hypo with lack of energy, heavy limbs, foggy brain, terrible memory and have put on half a stone since October! :/


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