T3 query

[Sailing14]

I never thought to ask on a recent post with help from TiggerMe who advised that the addition of T3 can drop levels of T4.

Could you advise why this would be?

Thank you to other forum members who may be able to advise also.

[DippyDame]

T3 also lowers TSH

The pituitary senses the increased level of hormone/T3 and sends a signal to the thyroid, via lower TSH, to produce less hormone... so both FT4 and TSH will be lower

[tattybogle in reply to DippyDame]

i have just been wondering about the mechanism for Liothyronine lowering fT4 .... if it was due to the lower TSH , then presumably it wouldn't happen in people who've had a thyroidectomy ?.... there are probably real life examples on here somewhere, meaning we could rule it in/ out , but no idea how we could find them , unless we come across them by chance ... it's something to look out for though ie. does this effect only happen in patients who still have some degree of working thyroid ? if you see what i mean .

[greygoose in reply to tattybogle]

Pretty sure it happens to everyone. I've never seen a set of blood test results where it didn't happen.

There have been several discussions on here about that since I've been here and no-one has been able to come up with a scientific reason. There are those that insist that it's because taking T3 increases conversion of T4 to T3, but I cannot see how or why that would work, nor how you could prove it. So I think the answer is: no-one knows.

[tattybogle in reply to greygoose]

Thanks for being the memory bank gg...., you're much more use than the search facility.

re conversion improving, see below from Tania, i haven't read it in enough detail to see where she got it from though . i have difficulty remembering which deiodinase does what/ where/ how , so i struggle to get my head round it .

[Sailing14 in reply to tattybogle]

Thank you. I have asked DippyDame the same question.

Out of interest, do you still have a thyroid?

[tattybogle in reply to Sailing14]

yes .

[DippyDame in reply to tattybogle]

I think it applies to everyone... but will work a bit differently for the individual!!

Maybe we're looking for a complex scientific reason when it's actually an overlooked straightforward reason!

But.... I'd best go and read Tania's piece now!

Like so much thyroid stuff there are probably more questions than answers!!

Best probably just to accept it happens and don't give the medics a reason to interfere with our T3!!

[Sailing14 in reply to DippyDame]

Thank you very much. I will read through this evening.

[Sailing14 in reply to DippyDame]

Thank you. I haven’t got a thyroid. Does the same mechanism apply?

[DippyDame in reply to Sailing14]

I assume it should....but no specific proof!!

[tattybogle]

maybe .... a bit of what DD suggests ie. lower TSH leading to lower T4 production from thyroid )

and also perhaps , a bit of this : thyroidpatients.ca/2021/02/...

"2. Low T3 will downregulate D1 enzyme, hindering T4-T3 conversion rate in D1-rich tissues like thyroid, liver and kidney, while higher T3 will do the opposite."

So when T3 is higher, more T4 is converted to T3, so there is less T4 left ?

[greygoose in reply to tattybogle]

That's the theory some people adhere to, yes. But, like most things thyroid, theories are just theories and more than likely fact varies from person to person. And I can't see how you could prove it in any one individual.

What's more, as a theory, I find it slightly dangerous because if it were general knowledge, some doctors would be using it to reduce the amount of T3 they're willing to prescribe. As with any theory, it will be more useful used against us than to help us!

[tattybogle in reply to greygoose]

it seems illogical doesn't it ... why would more T3 cause more conversion to T3 ... you'd think the body would protect itself from too much T3 by causing less conversion.

i'm going to read the papers she is referencing to see if it sheds any light ... but i doubt it will... if the answer was obvious , someone on here would have found it already .

at first glance they seem to be about hyperthyroidism, so the mechanism they are referring to might not apply in people without hyper levels ?

[DippyDame in reply to greygoose]

Good point....we need to protect ourselves from the anti T3 mob!

[radd in reply to tattybogle]

tats and Sailing14

Theres plenty of science available in addition to DD's suggestion of reduced TSH, such as adding T3 increases the conversion actions of enzymes D3 and D1. D3’s effect on T4 is to reduce levels by conversion to RT3, and D1’s effect on T4 is to reduce levels by conversion to T3.

These enzymes also congruently adjust each other, so up-regulating D1 & D3 will also up-regulate D2 to an extent meaning T4 lowers further through further conversion to T3.

FT4 doesn't always drop in people who introduce T3 meds. It depends upon your genetics and thyroid physiology. Good explanations can be found from Tania Smith and Antonio Bianco - King Of The Deiodinases 😁

[tattybogle in reply to radd]

thanks , i'll read that properly in a minute

[radd in reply to tattybogle]

Sailing14

Simple recap on the deidinases of which there are three thyroid hormone conversion enzymes, D1, D2 and D3, acting as control points making our thyroid hormones work well or de-activating them.

Each enzyme changes in response to differing physiological conditions as well as effecting each other. Eg FT3 concentration in different tissues varies according to the amounts of hormone transported AND the activity of the tissue deiodinases. This prevents over stimulation in one area whilst another might not be receiving enough.

[Sailing14 in reply to radd]

Thanks again. That makes more sense to me now

My endocrinologist always says stress and physical pain affects the TSH or ‘the thyroid’ is how he put it, but I don’t have a thyroid.

Are you able to simplify this?

I need to ask next time I see him but I don’t always get enough time to go through everything at the appointment with him.

[Sailing14 in reply to radd]

Thank you. It’s a lot to take in and understand.

I will read through the article to see if it makes a bit more sense and also your explanation. I haven’t got a clear brain at the moment but I’m sure after a cup of tea it might sink in more.

[radd in reply to Sailing14]

It's extremely complicated, and there's many further reasons why T3 reduces in the presences of T3 meds.

I've just remembered the binding proteins which have a much stronger affinity to T3 than T4. Therefore, when meds are raised, more T4 than T3 risks being lost in urinary excretion as the body tries to balance levels even if T4 didn't need to be lowered at that time.

I suggest you read tats link to Tania Smith. She is excellent in explaining and provides supporting references.

[Sailing14 in reply to tattybogle]

I think I understand but it is complicated and I don’t understand what happens if there is no longer a thyroid. I take my t4 but how does TSH mechanism play a role if I haven’t got a thyroid? Does the t4 convert without relying on the TSH?

[tattybogle in reply to Sailing14]

conversion of T4 to T3 , (orT3 to T2 , or T4 to reverse T3 etc) happens all over the place in the body ,,,in some places more specifically than others.

it happens thanks to the deiodinases ( enzymes) within cells ...

there are 3 sorts of deiodinases (Dio1 , Dio2 ,Dio3), and they each do different things. ( basically Dio1 and Dio2 can both make T3 out of T4, and Dio3 gets rid of T3... but it's more complicated than that )

so , different tissues/ organs have more of one kind than another . ... and different levels of T4/ T3 / TSH can change the amounts of each deiodinase within each cell.

so TSH and T4 and T3 levels can all have an effect on conversion, even once the thyroid is no longer present ..but i think the effect might be quite small.

...... and at that point i usually give up trying to get my head round it .lol

[Sailing14 in reply to tattybogle]

Thanks a lot. I will have a good read through this.

No wonder we are we are as it is a very very intricate balance to try to achieve with our replacement hormone/s.

[tattybogle in reply to Sailing14]

yes , it's no wonder.

Far from being 'simples' as many doctors / endo's have been taught to believe , the body's mechanism of regulating thyroid hormone action is fiendishly complex, highly intricate . highly individual , and highly dependent on whatever else is going on in the body at the time .

personally, i think this complexity is why most of em have little or no interest in treating hypothyroidism, or in learning more about it ... they start to realise that it's like knitting fog ....so it becomes much easier to blame the patient .

the only answer to 'individuals having problems' is individual experimentation on a 'suck it and see' basis ......which is very time consuming with no guarantee of success ..... take's a particular sort of person to want to get involved with that ... most of them can't be bothered with it .

[Sailing14 in reply to tattybogle]

This is very true and our hormones are so important to how well we function day to day.

We have a silent disease from the outside and that is our problem and also research into this condition. Medical people are heavily into diabetes research and treatment for which it should be, but why not this condition as when things go wrong through absorption issues later in life and developing food intolerances, to lactose intolerance, conversion problems when you were converting before. My endocrinology couldn’t answer that one. To T4 preparations, fillers, obtaining the same brand and then t3 and it being very rare to need this but why is this so? Then trying to obtain it from a private source in case the GP changes our t4 when it could be the last thing we need. Private blood tests. It goes on and on doesn’t it.

Always so much to learn and wider family can’t be expected to know but it is them that we need to fully understand what we go through.