Thyroid UK
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Help needed with understanding RT3 ratio

Hi guys, big thanks to all who contribute to this site for all helpful info over the years. Had some medichecks done recently and trying to understand the role of RT3 and the 'RT3 ratio' figure. Results:

TSH .696 (0.27-4.2)

FT4 20.1 (12.00-22.00)

Total T4 98.4 (59.00-154.00)

FT3 3.44 (3.10-6.80)

RT3 19 (10.0-24.00)

RT3 Ratio 11.79 (15.01-75)

As I understand it I am not converting but does the ratio figure support this? Can anyone explain without getting too technical? I have been trying to understand facts given on National Academy of Hypothyroidism website about hormone transport as I think my problems relate to "inadequate cellular energy". I'm not auto immune but had partial thyroidectomy. Many thanks in advance

3 Replies

I don't go in for ratios, personally, but your rT3 is high-ish, because you have too much unconverted T4 in your system. If it's not converted into normal T3, the T4 has got to go somewhere, so the body converts it into rT3, which is subsequently converted into T2, and is therefore not wasted.

What supports the fact that you don't convert well, is comparing your low FT3 to your high FT4. There shouldn't be that huge gap between them.


Thank you for replying. It's good that my assessment is confirmed.


You're welcome. :)


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