I've been treated for 25ish yrs for hypothyroid & take T4 & T3 (self sourced.)
My TSH is suppressed, which makes perfect sense to my non medical slightly addled brain. Of course my previous GP didn't like it and because I refused to stop my T3, slowly took away my T4. I've been dealing with B12d for 8 months, and decided that I'd get on top of that so that whatever is left must be a hypothyroid symptom. In theory.
Anyway had bloods done recently that my new GP didn't like and I was called in for a f2f tomorrow.
The thing that I don't really understand about my condition is...... What does T4 do in addition to converting to T3? I understand that the T4 is converted to T3 when things go well, but does it do anything else? Why do I need it if I take T3?
For interest my results were......
Serum free T3 4.6 (3.50 - 6.50)
Serum free T4 5.0 (7.00 - 17.00)
Serum TSH <0.01 (0.38 - 5.33)
My dosage is 50mcg T4 & 30mcg T3 (split dose)
What was it Spike Milligan had on his headstone? " I told you that I was ill"
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debra_bill
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Good question! But I don't know if anybody knows the answer. There are all sorts of theories but I don't think there's much proof. For me, it just makes me ill.
Why do I need it if I take T3?
Well, not everybody does. It depends on the person. I don't need it and don't take it. But some people don't feel good unless their FT4 is quite high-ish. You just have to find out by trial and error if you need it or not.
But one thing I will say, your FT3 is still quite low, and increasing your levo might just bring that up a bit. It depends. That's all I can say.
I was started on T4, but still wasn't 'me.' I had a good endo who said 'let's try T3, I don't know if or why it works, but it might just help.' And it did!
I felt pretty good for years on the combination, so assume that I need both. It doesn't really make sense to me, so it's a hard case to argue.
I want my levo back up to 100mcg ideally with 20 to 30mcg T3, which is where I was when I felt good and could control my weight.
I think the B12d started to cause symptoms and the GP reduced my T4 at the same time, so it's difficult to know exactly where I should be, but I think that would be good place to start from.
Thank you for answering my question, it's good to know that I'm not the only one who doesn't know!
I had a good endo who said 'let's try T3, I don't know if or why it works, but it might just help.'
😂😂😂 He doesn't know why it works? Because it's the active thyroid hormone needed by every single cell in your body to function correctly. I always say that doctors haven't a clue what T3 is or what it does and people don't believe me. But, there is the proof!
so assume that I need both.
Why would you assume that if you've never tried T3 only?
One good thing about T4, if you can tolerate it, is that it gives you back-up. Imagine something happened - don't know what, but something - and you couldn't get your T3 for a while. The T4 would assure that you did have some T3 in your system even if it wasn't enough. So, if you can take it, I think you should. I'm not T3 mono-therapy from choice but necessity - T4 makes me ill.
It was 25 years ago, he's long gone now. I was on 200mcg levo at the time, but still not good. In his defence I think that he knew I needed T3, but not why I didn't make my own. At least he got that numbers on a page aren't the answer, he was interested in how I felt.
If they up my T4 and it helps then I may just stick with it. I have considered trialling T3 only if they won't up my T4, but need to get my B12d under control first, this summons by the doc has scuppered my plans tbh!.
Well, he may be long-gone, but thyroid knowledge hasn't improved in those 25 years. The average GP/endo still doesn't know what T3 is or what it does because they're not told in med school.
T3 only should be a last ressort anyway. It's rather a precarious way to live. If you're good with what you've got, stick to it, even if they won't increase the dose. You could always buy your own?
I'm not sure we have ever found a direct action for T4.
However, its conversion to T3 isn't quite as straightforward as might initially appear.
Yes, some conversion takes place in the liver and other organs - and gets released back into the bloodstream to be circulated.
But some organs do much of their own conversion - the brain, hair follicles, etc. The brain has a very complex system for managing conversion and T3 levels.
We also need to be aware that conversion of T4 to rT3 also occurs. Then both T3 and rT3 can be converted to T2.
And both T4 and T3 affect things like the amount of TSH the pituitary produces.
T4 appears to provide a way of keeping a significant amount of "thyroid hormone" available in a form that has little effect. And it also allows "thyroid hormone" to be carried round the body without necessarily having much (if any) direct impact.
That is, we end up with a somewhat confusing picture. And few definitive and clear answers.
When I first came across people on T3 only, I struggled to get my head round the idea. How could they do without T4? Yet quite a number of people - members here and others around the world - do appear to be pretty well on T3 only. And I give more credence to someone living on T3-only than the theoretical "must have T4 within reference interval" claim.
Your FT4 isn't high enough for T4 to convert to rT3
"rT3 is the inactive form of T3. When your T4 gets too high, it starts converting to more rT3 than T3 so that the FT3 doesn't go too high - it's a sort of safety brake to protect you. But, if you're a poor converter, having your FT4 too high can make your conversion even worse. But, don't worry about the rT3 itself, it's just a way of recycling the componants of thyroid hormone, because it is then converted to T2."
Thanks to greygoose for that explanation from some time ago.....no point in me rambling on when we have an excellent "greygoose-response"!
Of course my previous GP didn't like it and because I refused to stop my T3, slowly took away my T4
Since your Free T4 is now below range your doctor is just being sadistic (assuming that you need the T4 to feel well), and is treating your TSH only. There is no guarantee that your TSH would rise even if you stopped T4 altogether. And I don't think there is anything in the guidelines that insists the patient must be punished it they take T3, but that is what your doctor appears to be doing.
I spent years on T3 only, but never felt particularly good - but adding T4 made me feel even worse until about three or four years ago. I spent years trying to improve my iron (too low) and cortisol (too high), and having got quite close to achieving that I found I could tolerate T4 for the first time.
But tolerance of thyroid hormones varies from person to person.
What does T4 do in addition to converting to T3?
One of the main purposes of T4 is to act as a reservoir of the raw material needed to create T3. Suppose you ordered T3 but couldn't get hold of it for some reason. At least for a while your body would be able to create its own T3 from any T4 you had stored in your body, also from your tablets, and also from your thyroid assuming you still had a thyroid and it still worked to some extent. But depending on how well you convert T4 -> T3 and how much T4 you had available to you you might run out of thyroid hormones within a week or two. You would feel terrible though if both your T3 and T4 ran out and you had no way of topping either of them up.
P.S. If you need Levo and T3 to feel well then I would say your results and doses are much too low. As greygoose has said in the past, TSH doesn't make you feel anything. In someone who feels well and optimally dosed for them the TSH doesn't really have much (or any?) direct impact on symptoms. The most important thyroid hormone is T3. Every cell in the human body needs T3.
In a healthy person with a healthy thyroid i.e. with no need to supplement thyroid hormones at all, about 20% of the body's T3 comes from the thyroid and the remaining 80% comes from conversion of T4 to T3 in various organs in the body e.g. the liver, the skin, the kidneys, and probably elsewhere.
But don't forget that thyroid hormones in those with hypothyroidism are delivered to the body in big chunks (i.e. when they take their pills) rather than in tiny dribs and drabs throughout the day and night as they are in those without hypothyroidism. The desire of doctors to keep TSH in the same range as that of healthy people ends up under-dosing the patients.
It feels like punishment to me too, I'm hoping that my new GP will at least listen. Someone has clearly had a wobble when they saw my results, low T3 or not, or they wouldn't have called me in.
No one ever mentioned suppressed TSH until the price of T3 went up. My previous GP treated me like a fool when I asked why I would produce TSH if my body doesn't need it because I'm supplementing with the exact thing TSH calls for.
One thing I have found is that when I start to get palpitations and have a blood test, even though I am either over treated or under treated (if that is what it is), when I increase or decrease T4 (whatever the case may be), my palpitations cease straight away (although I get the odd ones but not the same as when the above happens).
Could it be that T4 and T3 etc work differently on our organs i.e heart in my case and what they require?
Although, I am still on the journey of trying to get well with this condition, and even though you can solve one issue it doesn’t mean you are as well as you should be by any means.
Some people are fine on just T3 …..in which case Ft3 will be high and Ft4 extremely low and dose T3 typically something between 40mcg to 60mcg daily….depending on the person
But others find they need both Ft4 and Ft3 at least 60-70% through range
You might try experimenting with 25mcg more Levo to see if this would improve symptoms
It would increase Ft4 and Ft3
Recommended that all thyroid blood tests early morning, ideally just before 9am, only drink water between waking and test and last dose levothyroxine 24 hours before test
This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)
T3 ….day before test split T3 as 2 or 3 smaller doses spread through the day, with last dose approximately 8-12 hours before test
is this how you do your tests
Important to test vitamin D, folate, ferritin and B12 at least annually
Testing last time was strictly by the rules, except 9.05 was the earliest I could get.
I'm going to ask (again) for VitD, Ferritin & Folate testing, though I've been supplementing anyway for a few months to support my B12 injections. My B12 was 80 (range 200 - 900) and I was getting nowhere fast with the NHS, so self treating with GP knowledge.
I don't think there is a definitive answer but I guess if it isn't optimally converting to T3 then it's purpose is diminished
Briefly....T4 to T3 conversion provides a longer smoother supply of T3 than taking synthetic, but biologically identical, T3....it's the body's way of providing what is a vital hormone.
Why do I need it/T4 if I take T3?
The T4 that you are taking may still be producing some useful natural T3
If the conversion process is impaired then the resulting low T3 has to be replaced by exogenous T3...the amount will depend on the conversion status.
For good health every cell in the body must be flooded with T3 by way of a constant and adequate supply
Low cellular T3 = poor health!
I need high dose T3-only to function but that decision was the last resort.....and involves another thyroid condition not relevant here.
After nearly 20 years ,T4-only left me very unwell and barely able to function....it had to go.
I self medicate out of necessity....not choice
It's essential that you optimise vit D, vit B12, folate and ferritin to support thyroid function conversion
Everyone is different and requires a different solution which doesn't always make for easy solutions or answers ...as we all know
I suspect your dose needs tweaking and symptoms as well as lab results will help do that.
But, if you feel well stick with your current dose....if not something needs to be changed.
TSH is not a reliable marker, it adds nothing , so do not allow your GP to dose you according to your TSH level...it won't work!
I don't pay much attention to my bloods, because I'm more interested in how I feel, but every now and then the results match the symptoms. Et voila! A GP appointment, and a f2f one at that!
My last GP sent me a nasty ex communication letter when I tried to advocate for myself, my new GP has yet to show that they are much better. They wrote to an endo, who consulted by reading some random notes (nothing beyond the name & dob related to my history) and sending a letter back. Didn't speak to me at all. His response was ....suppressed TSH, no extra T4 required and tell her 'to stop her self medicating habit.'
I had a rant at the wall and started injecting B12 to get to a point where I can be bothered even discussing my thyroid.
How much T4 are you currently taking, sorry I read your GP had reduced/ taken away your Levo. I'd be very tempted to tell them that if the NHS treated thyroid disorders with the respect they deserve, we wouldn't be buying meds from the internet.
Sorry I've come in to add a post GP apppointment update, and that comment looks a bit abrupt! In my head it was purely an admission of defeat. I had excommunication threats from my ex GP, from making a joke with a receptionist who had no sense of humour. I'm afraid that I'm nervous of making too many waves with my new GP, who I assume has seen the letter on my records..
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