Thyroid UK

Just had some tests back. I don't understand why free T4 is low end is it to do with T3 maybe?

Hello just had results back can any thoughts please.

FT4 11.1 (10.5-26 pmol/l)

TSH 0.21 (0.35-4.5 miu/l)

free triodothyronine level 4 (3.9-6.8 pmol/l)

I have lost weight since Jan almost a stone but this was through a slimming class so trying to.

Usual tiredness etc but feeling anxious and BP a bit high hence trying to lose weight to help.

I was wondering about changing med dosage . I take 75mcg thyroxine am, and 20 mcg triodothyronine split half am half at 5pm ish. Did blood early am without taking meds in the morning. I take HRT and try to take it apart from thyroid meds

Thanks all

4 Replies

TSH and FT4 will always be lower when taking T3.


Everything looks low. You'd expect low TSH and T4 if taking T3, but not T3 at the bottom of the range - perhaps you need an increase - anxiety etc are hypo symptoms.


Thank you for your comment. Yes I have been thinking of upping T3 to 30 mcg. I was just wondering if it would make T4 and TSH even lower. I find this all confusing and not had such low figures after taking T3. Still I can try it for a while and see how I feel.


If you take T3, T4 and TSH will be low as they aren't needed so much. TSH is really irrelevant (unless you are not on meds and it is really high or really low) as it changes throughout the day and seasonally as well (and when you eat). Although there is probably a use for T4 itself, most of it goes to make T3, so if you are taking T3, you don't need as much T4.


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