Thyroid UK

The usefulness or otherwise of blood tests and timing and medication variation?

Dear All,

I see a lot of posts about the timing of tests and when to take your meds. Thought I'd post up my last 3 blood tests. I read in one of the posts that another member didn't find much variation in their T3 over the day, but mine is very different 24 hours after the meds compared with just 5 hours after. I figure my average FT3 during the day must be somewhere in between but I don't really know how it decreases(??). I don't notice any sudden tail off except feeling very tired by the evening.

I take all my meds in one go. I was taking them at 3am but it was too sleep disrupting so now I take them at 6am. I'm generally really starting to feel better now I've included T3. My motivation for life and personality is slowly starting to return which is amazing as I felt like a shell of a person a year ago. It just feels precarious self-medicating and I wish the NHS would listen to our experiences and medicate us properly. Like others on here, for ages I was offered anti-depressants and told I was stressed, burned out etc but my thyroid was 'normal'. I knew that wasn't frustrating! And when you're ill you can least defend yourself against the system.

I intend to stick with my current med levels for 6 months or so and then review.

2017 04 18: 75mcg T4, test taken 24 hours after last meds: (feeling quite unwell)

TSH 0.57 (0.27-4.2) FT4 11.6 (12-22) FT3 3.8 (3.1-6.8)

2017 06 30: 75mcg T4 & 25mcg T3 (built up over 2 months), test taken 5 hours after last meds: (feeling much better though tire easily)

TSH 0.03 (0.27-4.2) FT4 11.4 (12-22) FT3 8.4 (3.1-6.8)

2017 07 19: 75mcg T4 & 25mcg T3, test taken 24 hours after last meds: (continuing to improve and less exhausted by evening)

TSH 0.02 (0.27-4.2) FT4 9.0 (12-22) FT3 3.9 (3.1-6.8)

Best wishes and thanks to everyone for contributing into this invaluable forum.

8 Replies

Great news richar03 it inspires us all 😊

You may know there is a petition started by Kitti1 who also has benefitted from T3.

If you've not seen the petition the link is below. We need to sign, shout and share, so we are heard. Heading towards 3500 signatures but we need more.


Signed, thank you for sharing the link.


😊 keep on sharing 👏

1 like


Interesting thanks.

Have this info.

The half life of T3 (cytomel) is about one day. I have read other sources that say 12 hours, but I think that one day is more accurate.

What this means is that if you take your cytomel in the morning, then half of it is still in your blood the next morning.

The reason that we notice a difference after 6-8 hours after taking our T3 meds is that during that time, our FREE T3 is artificially high. After that time, the Free T3 has stabilized as proteins have attached themselves to the T3 so it is not as readily usable.

Splitting the dose allows us to do two things. 1. by taking a smaller dose, the artificial peak in levels is not as pronouced, and 2. by spreading the dose, the peak is spread over a longer time.

Ignore the FT4 as T3 will suppress. Keep an eye on T3 levels you ideally want to be nearer the top end of range.

Glad you're feeling better!



T3 peaks in the blood for upto 6 hours after ingestion but is out of the blood in around 8 hours but then moves into the cells. The short half life means it will be out of the cells 3 to 3.5 days from last dose.


wow....lucky you to be getting your energetic personality back..I am soon envious..not least because you mention the magic word: T3 ! wish we could get it. I would love to try it to see what difference it makes..but that's just a dream for us in the UK....

I couldn't agree more either with your comment relating to an inability (lack of energy) to fight the issues with the GP simply because of the disease.....very very frustrating! Have you signed the ITT petition for us brits??? hope so. Many thanks:) Shon


Hi - yes I've signed the petition! I'm in the UK too - I bought my T3 (Tiromel) over the counter in the chemist while on holiday in Turkey. I plan to go there on holiday every year from now on to stock up. I fear something going wrong with the supply, but it's worth it for feeling human again now. Cheers, Louise


Good stuff :)


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