Biological limit on how much T3 you can get out... - Thyroid UK

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Biological limit on how much T3 you can get out of treatment with T4 thyroid hormone alone (Canadian article)

TaraJR profile image

I read this on Canadian Thyroid Patients Campaign, and would like to hear people's opinions on it.

It makes sense when I read it, as it sounds like my experience, but I don't understand the science well enough!

I wonder if diogenes could comment at all?

18 Replies

Thank you for posting this. It is simple to follow and makes absolutely perfect sense. The idea that people will feel completely the same by throwing down a chunk of synthetic T4 every day is ridiculous and criminal in the suffering it causes. Our bodies fine tune all the time - does anyone really believe the thyroid just works first thing in the morning (with a glass of water -lol), by squirting out a load of T4 and then resting for the rest of the day? Of course not! So how can anyone suggest that T4 monotherapy is able to restore health? The treatment is inadequate and if you look at it really simply - stupidly so! 🤸🏿‍♀️

I sort of got it, however the thing about medical advice is that it's a thing that happens whether you understand it or not! So you don't have to worry about words, you just have to ensure that you are getting what you need out of your therapy. That's your job. If you feel you aren't being treated adequately because your medical consultant doesn't understand then print the article and ask them to read it, then advise on the strength of it. If they think it's tosh then you have two options. First you can believe them (they may quote more research etc, don't let them bs you, ask for references and quotes and bring them here for us to see). Secondly you could change consultant. This is the only bit you need to understand :)

Sorry that this is probably not what you wanted to here, it's not helpful as it could be, but if you are struggling with overwhelming info (and who doesn't from time to time, even experts disagree) then maybe you need to sit back and see things from another angle, sorry again.

PS I added 'sorry' twice because you are Canadian ;) and we spent a month there last year honing our politeness skills and learning our manners....

m7-cola profile image
m7-cola in reply to cazlooks

You make a very clear and helpful point: our task, as patients, is to tell our doctors what we feel, need and require of them. It’s a bonus (for them) if we also understand the science behind our condition.

MissGrace profile image
MissGrace in reply to m7-cola

And a bonus for us if they take any notice of what we say or just point robotically at a TSH result.

This has been known for some long while now and has been subject of many respecable peer reviewed published papers AND YET still the endocrindogist clique and the NHS so called advisory bodies deny the biology and the epidemiology (all of us complaining we still feel unwell on T4 monotherapy ) . This issue together with the doctrinaire reliance on TSH testing and possibly the gut /oral absorption of Levothyroxine issue together probably account for the most significant lack of wellness in so called 'treated' hypothyroid individuals.

The link between this and gut absorption in terms of the basic biology and available research data is that single large doses of T4 are not what the healthy thyroid gland delivers and for hours after Levothyroxine dosing free T4 peaks to unphysiological levels - it's simple logic to connect this with with the T4 mediated DIO2 enzyme inhibition mechanism,isn't it?!

And so, perhaps simply dividing T4 doses into 4 split equally over 24hrs can go some way to reducing the risk of iatrogenic (caused by the medication) DIO2 ubiquination / downshift. The addition of small physiologically normal amounts of T3 to replacement therapy is also logical and probably optimal for most people but especially those with a conversion handicap like a DIO2 polymorphism which in euthyroid individuals is quite likely compensated for by Slight increases in T3 production from the healthy thyroid. . .

Patients need a better coordinated voice to be heard by the clinician groups and advisory bodies!.. And we should rebut the NHS position on liothyronine T3 therapy based on cherry picked, non-prospective research that didn't include any significant data on poor conversion, individual setpoint variation or intracellular Vs plasma levels of free thyroid hormone! Not to mention an over-reliance on TSH to assert whether subjects were satisfactorily treated.....

Apart from stubborn ignorance and an insidious us V them clinician attitude bordering on the antoginstic is there also a low level conspiracy to Steamroller a one drug only replacement regime?

Diogenes is listed in the fourth reference.

Ubiquitin is a protein that can bind to several other proteins and affect their biological activity. D2 deiodinase is one of them. It is quite true that excess T4 actually inhibits T4-T3 body conversion. What happens instead is that the body mechanisms see the excess T4 as a kind of "poison" or "toxin" and in putting a ceiling on T4-T3 conversion, diverts the extra T4 to reverse T3 to get rid of it as soon as possible. The rT3 is quickly cleared out, compared with either T4 or T3, as it has a very short lifetime in the body. The control of D2 deiodinase is a very important feature of thyroid action control for the body generally. It stands as a last ditch in preventing the body's thyroid, when making too much T4, from converting the excess into too much FT3.

thyr01d profile image
thyr01d in reply to diogenes

Thanks diogenes for an interesting and informative comment. Can you explain about T3 in this regard? If one is on T3 only and were taking too much regularly (I'm not as far as I know btw!), would that lead to the same reaction in the body, in other words a negative effect? Apologies if I'm assuming you know more than can reasonably be expected, for some reason I have assumed you are medically qualified.

humanbean profile image
humanbean in reply to thyr01d

thyr01d You can read about diogenes and his career on this link :

He is Dr John Midgley and is one of Thyroid UK's advisors.

thyr01d profile image
thyr01d in reply to humanbean

Thank-you humanbean

diogenes profile image
diogenes in reply to thyr01d

If you are on T3 only, then there is by definition no conversion going on. All that is happening is that you are by taking T3 only, bypassing the whole system and simply taking in and using T3 direct . That's a simple matter then of choosing the appropriate amount.

thyr01d profile image
thyr01d in reply to diogenes

Thank-you, I did understand about no conversion but wondered what a body did if it was receiving too much T3 not via conversion.

diogenes profile image
diogenes in reply to thyr01d

Overtreatment - to be avoided owing to heart and bone dangers. On T3 only the body has no other option but to deal with what is swallowed.

thyr01d profile image
thyr01d in reply to diogenes

Thanks, that's interesting.

Missmina profile image
Missmina in reply to diogenes

Hi there

May I ask what is the effect of overtreatment and the heart and bone danger please? I also don't quite understand about the subject of calcium and cholesterol level. If you don't mind could you explain to me please? Thank you so much

This site is great and very helpful

Thank you so much.

Best regards

diogenes profile image
diogenes in reply to Missmina

Overtreatment on therapy will give you similar but not as severe, dangers of OP and heart problems as hyperthyroidism. Cholesterol is raised when hypothyroid or underdosed. Correct dosing should reduce it. Overdosing shouldn't be confused with suppressed TSH. You can have suppressed TSH with correct dosing or overdosing. Correct dosing with suppressed TSH has only the smallest effects on bone and heart and trials where they show anything at all, show only minimal problems.

Thank-you very much TaraJR for posting this, it's the simplest explanation I have read.

Hidden profile image

Interesting article, thanks for posting! I agree with a lot that's being said, but see a potential problem with NDT (being on NDT myself) as it contains a fixed ratio of T3:T4. If you need to increase your FT3 levels, and raise NDT, you will also raise your FT4 levels and excess T4 will be converted to reverse T3. So you may be better off taking pure T3 in addition to NDT if you only need to raise your FT3 levels...

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