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Thyroid UK
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Free T3 level - zero is normal?

I managed to persuade my GP to refer me to an endo, who did TF tests. The results, TSH 0.37 (range .3 to 5.5), Free T3 4.4(Range 0.0 to 7.0), Free T4 17.1 (range 11.5 to 22.7). My GP has called them all normal and is not intending to change my dose - 75 mls levo. I am really perplexed about the ranges for the free T3. How can zero be 'normal'. Does that mean if I have zero free T3, it is OK? I think my free T3 is low and intend to discuss this with the endo when I see him in Feb. Any comments would be appreciated.

5 Replies

Scazzoh, that is a peculiar range and it would appear that zero FT3 would be within normal range. :o 5.25 would be the 'ideal' 75% of range sites like STTM advocate but I don't think you'll find many NHS endos who'll agree with STTM. FT3 4.4, which is more than 50% of that peculiar range, will probably seen as acceptable, particularly if your endo insists on TSH being within range as an increase in dose will lower your TSH. It's certainly worth pushing for an increase if you are still symptomatic.

Have a look at this link where Dr. A. Toft discusses dose and levels thyroiduk.org.uk/tuk/about_... Email louise.warvill@thyroiduk.org.uk if you want a copy of the full article to show your GP or endo.

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Whenever I've had total cholesterol measured by the NHS the range started at zero. I thought that was barking mad. A zero Free T3 is barking mad too. I think you'd be comatose or dead with a zero Free T3.


I have commonly seen ranges of 3.9-7, but all labs differ. 0 is definitely wrong!


Think you ought to query that range - perhaps not with the doctor, because I doubt he'd be much help - but with the lab where they were done. Could be a mix up, somewhere.


Thanks for your comments. I shall contact the lab and talk to the end when I go back in February.


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