Thyroid UK
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T3 peak level raise first hours after taking NDT?

I was experimenting with thyroid-s last half year. All blood tests have been done after about 12 hours.

Taking 1 grain (half grain in morning, half grain at night) puts me into:

TSH 0.01 mE/L (ref 0.35-4.94)

T3 4.53 pmol/L (ref. 2.6-5.7)

T4 12.6 pmol/L (ref 9-19)

Taking 1 grain and quarter puts me into:

T3 5.5 pmol/L (ref. 2.6-5.7)

Somebody may think that 1,25 is my best dosage, but my sleep and mood is better on 1 grain than 1,25. Also libido is better on 1 grain, probably because 1,25 raises SHBG even more.

Without NDT my T3 is about the same as with 1 grain (after TSH falls down), but I think I feel a bit better on NDT even with the same level as I had it without. I am wondering is T3 4.53 when on NDT the same as T3 4.53 natural level? What is actual level first hours after taking NDT, is any higher than after 12 hours? Taking ONLY half grain every 12 hours, do you think that my levels may be at first hours 5.5 comparing to 4.53 after 12 hours?

4 Replies

I just found one great study: which shows peak levels of t3. In page 10 table 4 shows that t3 is more than doubled 3-5 hours comparing to 18-24 hours! That is a huge difference. So I guess that only half grain each 12 hours will put my T3 not just above 5 but also above 6 at least half time of the day which is more than my normal level. Anyway any thoughts from anyone is still appreciated.


The best way to know if you are on an optimum of hormones is 'how you feel' and blood test results are only a guide.

I have always taken a full range of horomone replacements and only one daily dose. I am well now, thankfully.

Testing bloods is recommended 24 hours after ingesting hormones as results can be skewed if we do it shortly after taking them.

T3 is absorbed quickly into our receptor cells (where all the work takes place) and this cannot be tested. When in our cells the effect of T3 lasts between one to three days.

This doctor was also a scientist:-


So this would mean 4.5 measured 12 hours after half grain is not the same as natural level of 4.5 measured without taking tablets but it is higher than that, probably equal to 5+. Correct?


Sorry for the delay in responding but I have been offline

I cannot answer your question correctly as I'm not medically trained.

You could put up a new post, with your question and someone who is more knowledgeable will respond. :)


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