Thyroid UK

Hormone requirements will change in relation to our energy output

Thought i would start a thread about thyroid hormones and what happens longer term in relation to energy and requirements.

I am pretty experienced with all the thyroid meds, but i take T4 only and a tiny bit of T3. I am generally well, but i do like to test things out and experiment a bit.

For a long time i was taking 125 T4 and doing well. Then i decided to up the T4 last year to 150. And i noticed an improvement. I had my annual blood test in December and my results were TSH 0.16 and FT4 19. All looks good, but the doc wasn't happy about the TSH. I had to go in and he wanted to take my pulse, but at 44 beats i am a million miles away from hyperT. So he agreed i could stay on 150 T4.

However, the issue with the TSH always niggles at the back of my head. It would be great to fit into that box. On 125 T4 my TSH was 0.4 and FT4 was 18.

So yesterday i wanted to see what 125 T4 felt like again. Would i feel different compared to 150 or would it be the same as 125 T4 that i was on for quite a few years.

Well the answer has hit me pretty squarely between the head at 11am this morning. I felt really tired. I have not felt like this for years. So i took more T4 at 1pm and i started to improve after 1 hour.

So what i think has happened here is that my body has gotten used to a higher level of energy input over time because the output has actually gone up over that time as well, all thanks to the new higher input of T4 at 150.

So even though my TSH is low my demand for T4 is just being matched by my 150 supply. Really it seems my body is running on quite a lowish level of fuel and without a top up it quickly runs out of fuel.

I am almost thinking i could easily use more T4 at 175.

My situation may be different to the classic hypoT patient as i am very active and play quite a bit of sport and work physically. So i am placing demands on my body and its energy supply. With improved health i am able to place more demands on the body and then i think i get into a state where i actually need more thyroid meds.

It just annoys me that the TSH is actually limiting my own treatment (and i am sort of telling the docs what i want to do).

I am thinking i am still quite far away from my optimum dose of T4. This is potentially good news. But would a GP manage to see round the TSH low level in the future ? I could imagine being on 200 T4 in the future and the FT4 is likely to be in the mid 20's, so actually in the range still, but TSH is likely to be even lower.

Food for thought i suppose.

Has anyone else experienced this sort of thing ?

ps, i take 3mcg T3 most days, Vitamin D, magnesium spray for the legs and a little progesterone (6mg).

10 Replies


>145mcg T4 is a suppressive dose. Why take any notice of TSH or require it to be at a certain level? Most people on Levothyroxine need TSH suppressed to deliver enough FT4 to deliver adequate FT3. My TSH is suppressed at 0.01 for almost 5 years. I've had several dose reductions and FT4 and FT3 drop after each dose reduction but TSH doesn't budge.


Do you get treatment on the nhs and are they ok with you having the suppressed TSH. How much of a battle do you have with the docs ?

Looks like my minimum requirement is 150, but could easily up it to 175 i imagine.



Yes, my treatment is on the NHS. Endo1 was okay about suppressed TSH but Endo 2 wanted to raise it to 0.05. I refused to agree to a third dose increase when TSH didn't budge because FT4 and FT3 are quite low already and I told Endo2 I would self medicate if she changed my prescription. Hopefully I'll be back on Endo1's list in April (they swap lists every 2 years) and won't have the same faff.


Marsaday, it's kind of a lottery whether you find a doctor who is strict on it or not. The most important blood test is freeT3, as it tells you how much active hormone you have. TSH doesn't tell you very much, and many people need it suppressed to feel well.


My Ft3 was always usually high - always in the 6's. I am going to have some blood tests done privately on monday so it will show FT3.

Very strange what has been happening to me. I seem to be needing more thyroid meds all of a sudden.


My TSH has been suppressed for years no matter what dose they faff around with to my detriment. I was also told I function on a higher dosage but they won't leave me alone. I really feel weary with it all and it's getting me down.

1 like

What dose do you take and are you ok ? Do you have an annual check then ? That is what i have and only recently have they asked me to reduce down.


Hi marsaday! I have two endo appointments a year, six monthly. I had my T4 reduced from 75mcg to 50 and take 40mcg T3. My TSH is less than 0.05, in other words undetectable, FT3 5.4 (3.6-6.4) FT4 8.9 (10-22). They wouldn't increase T4 back to 75 because of TSH. Awaiting vitD results and am requesting B12 off GP next week. I feel dreadful, totally exhausted but endo is convinced I'm vitD deficient. I was on 200mcg T4 only until I stopped converting efficiently and felt good on it but they were all concerned about my weight even though I told them I was careful with my diet and had a small appetite anyway. Chronic constipation proved I needed T3 and felt good on it to start with but with the reductions of T4 I've had since I do not feel well. Like you, I was told I function better and my body expects higher doses of T4 but they are all twitched when they see suppressed TSH and being so slim. I can't win and I can't keep awake! My best wishes to you.


You sound like a classic patient who really needs to work out your own levels in order to feel well. Leaving up to an end to guesstimate based on TSH will take years to work out.

Best to get some of your own T4 and see how you do on different T4/T3 mixes.

If you were good on 200 T4 then i would aim for around that level again and add in some T3 working upwards from a lowish level, not the 40.

VIt D is important and i have been using it most days now since autumn. I have thought whether the Vit D is making the thyroid usage go up, so leaving me depleted a bit with the T4.

I need to think about an increase to 175 T4 .


Increase was not the answer BUT a decrease was. Looks like i have been overmedicated and this has been causing a few issues. Pain in the chest has now gone and BP has come down.

Certainly looks like the Vitamin D has helped thyroid health meaning i don't need as much.

Taking 100 T4 now and no T3 at the moment. Doing very well so just holding and seeing how things work out.


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