What are the benefits if any of taking T4 alongside T3??

[Quasarlis]

What are the benefits of taking T4 alongside T3? I see people stating that they do? I don’t understand how this can be of benefit. As we all know the T4 is inert until converted into T3, we also know that it can be converted into RT3 which isn’t good! I was loaded with RT3 along with high out of range T4 and High out of range TSH ... Since switching to T3 only I feel so much better, my TSH is minimal .. We have a defective mechanism which the T4 plays havoc with, why not just bypass it and take T3 only that will cause your TSH to drop to bare minimum and therefore not trying to activate our defective thyroid ... That’s makes sense to me? Am I talking rubbish? Are there benefits of T4 floating around in our blood?

[Baobabs]

Within weeks of adding T3 to my Levothyroxine my FT4 plummeted and I felt very unwell until I increased my Levo until my FT4 became high in the range. Some folk on this forum seem to do well on T3 only. I'm not sure why T3 meds seem to affect FT4 levels like this in some? I'm not sure if any of my T4 is converted to T3 any more. Although I desperately needed medication 2 years ago because my TSH was almost 7, I think meds have made my thyroid 'lazy'.

[SeasideSusie Remembering]

If T4 didn't have a role, why does our body produce mostly T4 and only a small amount of T3? Even when some of the T4 is converted to T3 (and not all of the T4 is converted into T3) we don't have 100% T3 and 0% T4.

I believe that we are all different - some people do well on T4 only replacement and the body will convert whatever amount it needs to into T3. Some people only do well on T3 replacement alone. Some people need a combination of T4 and T3. Some do well with a low FT4, some need a higher FT4.

With my combo Levo/T3, I have had both my FT4 and FT3 are various levels through the process of tweaking doses to find what suits me best.

I have had my FT4 as low as 8% through range and I felt very unwell. It was only when I got it back up to 75% through range that I felt well again, and I need my FT3 at around 75% too.

This article is interesting verywellhealth.com/the-thyr...

[Baobabs in reply to SeasideSusie]

Almost same profile for me!

[greygoose]

Actually, we don't all know that T4 is inert. Some people believe it has a role to play. Who are we to say it doesn't?

As for rT3, that is neither good nor bad. It doesn't do any harm - not that we know of, anyway - and some think it has an important role to play.

The point is, we have no definitive knowledge of anything to do with thyroid. New discoveries keep being made that contradicts the old beliefs, but the fact is, not enough research has yet been done.

And, what's more, we're all so very different. A little - or even a lot - of T4 is necessary for some people to feel well. Myself, T4 makes me ill, I'm very happy on T3 only. But that's not the case for everyone. So, rather than suggesting that T4 should be discarded, we ought to be fighting for more freedom to chose.

[helvella Administrator in reply to greygoose]

I have long wondered how on earth people can do well on T3-only!

It is all very well writing of T4 being the inactive storage hormone - which might have some truth to it. But maybe the fact that in health, most of the T3 in our brains comes from conversion within the brain is important? The fact that the brain does much conversion also means it is in control of that conversion and distribution within the brain. (Not meaning to relegate the brain to an amorphous lump but my ignorance doesn't allow me to provide detail.)

[greygoose in reply to helvella]

I know. But, taking T4 made me so ill. Don't know why because my conversion was very good, and my nutrients were a work in progress, but…

So, I've been on T3 only for getting on for ten years, now - don't remember exactly. And, last year, as an experiment, I added in 25 mcg T4, with an appropriate reduction in T3, to see what would happen. And nothing happened. Everything was fine. No better but no worse. So, I upped it to 50 mcg, but that was a step too far. I started feeling bad again - just generally ill, hypo symptoms. So, stopped it altogether and went back to T3 only. I don't have any explanations.

[mfinn in reply to greygoose]

Thanks Greygoose. I do well on T3 only so I was especially interested when you mentioned that you were going to try some T4 and I've often wondered how you got on. Life would be so much easier if I used T4 but after hearing your experience of it, I think I will stick with what I know best - and carry on arguing with doctors!

[greygoose in reply to mfinn]

It's a pain, isn't it. But my experiment gave no tangible conclusions, which is why I didn't follow it up with another post. It was a non event! lol I wish I could report some positives results, but now I've read what MaisieGray has said about hair, I might try it again, and watch out specifically for that.

[Quasarlis]

You misunderstand me, I’m not saying it should be discarded at all, I was actively asking what the benefits are of the combination as I had read articles that T4 is converted into T3 as and when it’s needed, follow some endos on YouTube etc that suggest bypassing the whole process by taking T3 only can be beneficial, but it’s obvious that some people benefit from a combination of the 2 . And yes you are right there is much unknown about our illness.

[NWA6 in reply to Quasarlis]

I don’t know 🤷‍♀️ I was on Levo for 10yrs. I did enough conversion to keep me alive but it was a half life not a full life. If I increased Levo too much I’d get Hyper symtoms and yet no real raise/change in t3. So 🤷‍♀️ Levi allows me to continue to covert amdvni ive added T3 it makes up the shortfall.

I think keeping the T4 allows my body to decide when/where and how much to covert for the regenerations, daily labours of the body and upkeep. In that way we can take an approximation if T4, with T3 we have to be more accurate with our dosing and that is where it could potentially go wrong. I’m totally guessing. Can you tell! 😂

[Baobabs in reply to NWA6]

When I had to increase my T4 meds because my FT4 was very low and I felt dreadful it made no difference to my FT3 level, didn't seem to impact at all. This makes me think as has been said by others, T4 does have a possible unknown role to play in influencing our well being.

[greygoose in reply to Quasarlis]

Well, that in itself has got to be an advantage, hasn't it, converting T4 to T3 as and when it's needed. That would be far more natural than taking exogenous T3 in a lump - even if we do multi-dose. But, not everyone can do that, so it doesn't always work, but if you can do it, that would be much better, I would have thought. Although, given that the thyroid does make some T3, it would be even more natural to take both. Perhaps. The problem is, of course, that we're rarely given the choice, and that's one of the main things that is very wrong with the way we're treated.

[MaisieGray]

A 2008 study by van Beek et al showed that "T4 up-regulates the proliferation of hair matrix keratinocytes, whereas their apoptosis is down-regulated by T3 and T4. T4 also prolongs the duration of the hair growth phase (anagen) in vitro, possibly due to the down-regulation of TGF-beta2, the key anagen-inhibitory growth factor. Because we show here that human hair follicles transcribe deiodinase genes (D2 and D3), they may be capable of converting T4 to T3. Intrafollicular immunoreactivity for the recognized thyroid hormone-responsive keratins cytokeratin (CK) 6 and CK14 is significantly modulated by T3 and T4 (CK6 is enhanced, CK14 down-regulated). Both T3 and T4 also significantly stimulate intrafollicular melanin synthesis. Thus, we present the first evidence that human human hair follicles are direct targets of thyroid hormones and demonstrate that T3 and/or T4 modulate multiple hair biology parameters, ranging from hair follicle cycling to pigmentation."

[Quasarlis in reply to MaisieGray]

Good gawd!!!! 👊🏻👊🏻

[greygoose in reply to MaisieGray]

Interesting. Thanks for that.

[Baobabs in reply to MaisieGray]

Must learn to speak Swahili!

[radd in reply to MaisieGray]

Interesting to know T4/T3 conversion may also takes place in our hair follicles.

Many of us know thyroid hormones affect hair growth through personal experience, & there are many more factors that influence hair growth such as iron/cortisol levels.

T3 must do more than just down regulate or all the people medicating T3-only would surely end up bald. 😂

[Baobabs in reply to radd]

Perhaps our hair follicle area is so busy converting T4 to T3 that it forgets to produce our hair?

[radd in reply to Baobabs]

😂😂😂😂

[MaisieGray in reply to radd]

radd Well, such mechanisms take place in a pattern of checks and balances I would have thought, so I imagine it isn't a process that takes place in isolation of other complementary or counteracting actions ad infinitum. But in fact it says that "their apoptosis is down-regulated by T3 and T4" which I take to mean that the hormones reduce the death of hair matrix keratinocytes, not increase it. I could be wrong.

[DippyDame in reply to MaisieGray]

Hmmmm! If my thyroid hormones are out of kilter that is reflected in the state of my hair.....took me a while to work that out.

I'm Dio2/homozygous, have thyroid hormone resistance and take T3-only - currently 75mcg in a single dose - and at 73 years of age have very few grey hairs!

My RH finger nails (what is left of them) have thinned, peeled away look awful...but are very slowly improving with T3-only

Keratin etc etc?

T3?

[MaisieGray]

This is the abstract of a 2011 paper by Davis P.J. et al "Plasma membrane integrin αvβ3 is a cell surface receptor for thyroid hormone at which nongenomic actions are initiated. L-thyroxine (T4) and 3,3′,5-triiodo-L-thyronine (T3) promote angiogenesis and tumor cell proliferation via the receptor. Tetraiodothyroacetic acid (tetrac), a deaminated T4 derivative, blocks the nongenomic proliferative and proangiogenic actions of T4 and T3. Acting at the integrin independently of T4 and T3, tetrac and a novel nanoparticulate formulation of tetrac that acts exclusively at the cell surface have oncologically desirable antiproliferative actions on multiple tumor cell survival pathway genes. These agents also block the angiogenic activity of vascular growth factors. Volume and vascular support of xenografts of human pancreatic, kidney, lung, and breast cancers are down-regulated by tetrac formulations. The integrin αvβ3 receptor site for thyroid hormone selectively regulates signal transduction pathways and distinguishes between unmodified tetrac and the nanoparticulate formulation. The receptor also mediates nongenomic thyroid hormone effects on plasma membrane ion transporters and on intracellular protein trafficking."

Which I think is saying that T4 can be deaminated (converted) to tetraiodothyroacetic acid (Tetrac), shown to inhibit tumor growth, while T3 and T4 stimulate it.

[HIFL]

The body has T4 receptors, and if you have no T4, some biological processes don't occur. They are obviously not essential to life, or T3-only people wouldn't be alive, but you are short-circuiting mother nature when you take only T3. Interesting reading: tiredthyroid.com/blog/2015/...

[Hidden in reply to HIFL]

I was short circuited on T4 only and ill on combination of T4&t3. So T3 only is what keeps me well and alive and that's what I have to go with. From 20 years of hypothyroidism I know my body and what works. I don't care what has been written. T3 is a godsend to me. Thank you

One other thing did y'all know that JFK was on T3- Liothyronine only for his hypothyroidism. He had poly endocrine disorders.

[Baobabs]

Whatever ..................... I do love all this stimulating discussion and to see the amazing will of folk to help one another.

[Marymary7]

But surely if we take only desiccated thyroid NDT we are getting all the parts needed including calcitonin and t2. I'm not an expert I think maybe we are getting more than that.

Why is it that NDT doesn't work for some?

I've been experimenting with NDT and one 25 mcg of T3. Still not right and still gaining weight ☹️

[Hidden in reply to Marymary7]

Yes, I was on ndt's for six years in all and I put 5 stone on barely eating. BUT!!!! What should I of expected , have you ever seen a skinny 🐖 pig 🙄

[SeasideSusie Remembering in reply to Hidden]

have you ever seen a skinny 🐖 pig 🙄

That made me

[MaisieGray in reply to Hidden]

In fact, as nature made them, the amount and type of fat in a pig carcass is quite similar to that in other red meat animals. Unfortunately since the 1950's they have suffered from being intensively artificially genetically modified by the farming industry (as a result of which, the incidence of sudden pig death, or Porcine Stress Syndrome, in the US for instance, acutely increased in bulked up animals as a result); and have continued to have their bodies deliberately modified by intensive and distorted feeding patterns.

[NatChap in reply to Hidden]

😂

[MaisieGray in reply to Marymary7]

Pigs' thyroid produce thyroid hormones in a different ratio than a human thyroid. Whether that suits or doesn't suit someone taking it seems to vary. When I took NDT I was no better or worse than taking a synthetic combo of T4/T3 and medically could have happily continued taking it, but as I was self-sourcing the NDT it seemed pointless to continue paying out if I was apparently getting no medical advantage over what I was being given by the NHS. Others don't do well on it at all, and there is a view held by some, that due to its similarity to human gland it is a target or prompt for further autoimmune attack in those with Hashimoto's. I don't know if that assumption has been definitively proven or disproven more recently. Whether other than T3 and T4 make it through the desiccation process, and if so, in what amounts, is an unknown, or more accurately, is unstated by the pharma manufacturers; but when you say that you think we get more than each of the five hormone products of the thyroid gland, what are you referring to?

[Marymary7]

Exactly that. Five hormones as apposed to just T3 and T4. I have Osteopenia so wonder if the calcitonin will help at all and what role do they all five play. I take your other points which are very valid.

I don't know what to do for the best with a limited budget to pay for tests and meds! 😀

[Yazz1]

I have been on levothyroxine for over 20years it's not helped at all I was diagnosed with hypothyroidism/graves disease when I was 19 put on levo didnt help then couple of years ago was diagnosed with Hashimoto's still on levo still feel crappy. Recently started taking T3 and straight away I'm starting to feel better not so tired anymore and less pain in joints. I started off taking half a tablet with 100mcg levo but now it's the opp half levo and full T3 I can go the whole day feeling good. It's a shame I have to monitor what dosage to take without the help of endocrinologist.