Reverse T3 and what to do about it: Ok, so having... - Thyroid UK

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Reverse T3 and what to do about it

JonnyA profile image

Ok, so having done some Googling I am conscious that there is some skepticism on here as to the relevance of Reverse T3, however I've also read several accounts which suggest it CAN be a very real problem (or at least an indicator of one), so I'd appreciate some open discussion on the matter. Some links supporting the concept of RT3 being problematic:

I'm not your typical thyroid patient. For a start I'm male, and secondly I was relatively young and fit, 32, when I began exhibiting symptoms of hypothyroidism in 2017. These symptoms have become increasingly agonising and debilitating, to the point that I've been driven to the brink of suicide despite increasing (self-earned) wealth and a beautiful wife and two young kids. It's been absolutely gruelling.

I've spent thousands of pounds seeing private specialists of various specialisms and slowly buy surely, virtually EVERYTHING has been ruled out. Eventually, I found an endocrinologist who was willing to attempt treating what was diagnosed as sub-clinical hypothyroidism (TSH was just over 5, FT4 good, FT3 a little bit low).

That treatment has ultimately done nothing for my symptoms, almost a year in now, despite my levels being almost text book. No change whatsoever. And then recently I came across some old medical notes which shows my TSH was over 4 years before these symptoms even started, and then back down again a couple of years later, which has really made me begin to doubt whether my issue is one of typical hypothyroidism.

So here's the thing. Between February 2016 and the summer of 2017, I lost around 6.5 stone having been advised to lose weight by my doctor (from 17 stone to 10.5). I went from a body fat of around 30% to around 10% through a combination of intermittent fasting, improved diet and rigorous exercise.

That said, eventually I did find keeping in shape increasingly difficult. And then I'd cut the calories a bit more. And then a bit more. And then some more again. To the point that I'd be training twice a day, six days a week on little more than a 1,000 calories a day - largely protein. With hindsight, I got suckered into incrementally reducing my calorie intake by changes in my metabolism that I was not fully aware of in the moment, and I hold my hands up and say that I messed up, but I'm paying the price and ultimately I am where I am.

Pretty much every source I've read on RT3 quotes 'starvation / severe calorie restriction' - that's definitely where I was at one point, as mad as that was, looking back. With that in mind, I recently took a Reverse T3 blood test, and the result came back on Friday showing me to be way, way above range. My result was 70 ng/dL, with a quoted range of 8 - 31, however reading up it seems that anything north of 10 - 15 is considered problematic.

For me, this was a bit of a lightbulb moment. For any RT3 skeptics out there, please consider for a second:

- My symptoms began a few months after introducing a significant daily calorie deficit in order to lose weight, and doing so accordingly

- My symptoms are absolutely crippling, and absolutely consistent with severe hypothyroidism despite having, at worst, 'sub-clinical' bloods

- Getting my bloods to completely normal levels has had no effect on my health whatsoever, if anything I'm worse than ever now

- I've already ruled out virtually everything - some kind of thyroid issue was my last roll of the dice

- My RT3 is exceptionally high

All things considered, I can't walk away from such a hypothesis with little more than a "RT3 is a myth that's been debunked" quote on a forum as the reason - I'm quite literally losing the will to live here and I owe it to my family and myself to dig deeper. At the very least, I'd want to see my RT3 in optimal range to at least rule it out as I continue to search for answers.

So with that in mind, does anyone know where I might be able to find specialist support for this particular issues? Many endocrinologists I've spoken to in the past seem dismissive, but then I don't think my unique circumstances are typical of your average thyroid patient.

The consensus seems to be that the answer, in addition to addressing the original cause, is to dose with T3 only medication in order to suppress TSH and T4, in turn preventing the production of excess RT3 (as it requires T4 to exist in the first place). However, I can't find much online in terms of dosing guidance .

Any advice genuinely greatly appreciated!

Thanks! :)

90 Replies

JonnyA In the Stop the Thyroid Madness item in the link above it states:"..... Free T3 is extremely low–the result of excess RT3 blocking the cell receptors from getting T3. Very common." This is incorrect. RT3 does not block T3 receptor cells.

JonnyA profile image
JonnyA in reply to Lalatoot

A couple of things here. Firstly, I had read this article previously and this is why I referenced that RT3 may be an 'indicator' of a problem in my opening paragraph; it may not be the problem itself, but indicative of something else that is. The article you quoted is a little technical for me as a laymen, but I inferred from it that RT3 are at least interrelated (I could be wrong on this of course).

Secondly, this is rather indicative of the problem I have. There's so much contradictory information out there on RT3. You have started, as if a fact, that it is simply incorrect that RT3 blocks receptor cells, and quoted a link accordingly. There are others which would back up your claim, but also many others that would contradict.

I have to try and piece the reality together from all of this information and my own personal experience, and it's both difficult and exhausting.

Lalatoot profile image
Lalatoot in reply to JonnyA

Johnny It used to be thought that RT3 blocked T3 receptor cells but more up-to-date research has altered that thinking. However not all sites are up-to-date.

Again this article discusses how chronic illnesss or strict dieting causes changes in deiodinases which in turn causes high RT3:"Altered intracellular thyroid hormone metabolism results from metabolic changes caused by the condition itself, and it is these changes in expression of the deiodinases that induce the rise in rT3.:

Low T3 syndrome (with elevated rT3) is a consequence of starvation, a defence mechanism for times of famine. Have you resumed a normal diet now, with adequate calories?

JonnyA profile image
JonnyA in reply to jimh111

Yes, for at least 18 months now. Symptoms frustratingly remain.

Are you able to explain this to me in laymen's terms, please? The articles playing down the negative role of RT3 all reference deiodinases but I'm unsure as to their connection.

greygoose profile image
greygoose in reply to JonnyA

Not sure who you are replying to, here, but I'll try and explain...

One molecule of the thyroid hormone T4 contains 4 atoms of iodine - hence the name.

T4 is basically a storage hormone that doesn't do much until it is converted to T3.

Conversion is acheived through a deiodinase (de-iodin-ase) removing one atom of iodine.

If that atom of iodine is removed from one position on the molecule, it becomes T3. If from another position, it becomes rT3. There are three differenct deiodineases, I think, that do different things according to the situation.

There are many, many reasons for the body converting T4 to T3, but they are all done for the benefit of the body - as jimh111 explained above referring to starvation.

Also, if your FT4 is too high, more of it is converted to rT3 than T3 - normally, it would be 50/50. This is to prevent you from having too much T3 in your system and becoming hyper/over-medicted.

Always look at the dates of the articles you read. The discovery that rT3 has it's own receptors, and therefore does not block T3 receptors, is a recent one. But, also, you should know that rT3 is inert - i.e. doesn't do anything - and only stays in the body for about two hours before being converted to T2, as part of the recycling system of iodine.

People often think that their rT3 is causing their symptoms, when in reality it is the low FT3 that is causing them - if you are a poor converter, your FT4 goes too high, with the resulting high rT3 levels, but low FT3. You haven't given us any actual numbers for your hormone levels - results and ranges - so it's impossible to know if this is what's happening to you. Or, you could just be under-medicated - which is more frequant than one could possibly believe! Doctors prefer to under-medicated their patients because they are terrified of hormones!

So, rT3 apart, if you post some blood test results, we might be better able to help you. :)

Also, on the subject of starvation, most anorexics end up hypo, and the hypothyroidism doesn't tend to go away when they start eating normally again. Calories are necessary for correct conversion of T4 to T3, but extreme circumstances can alter the bodies set points irreversably.

On the other hand, it could be nothing to do with that, and you might have become hypo, anyway, and hypothyroidism was the reason you put on weight in the first place, so don't go beating yourself up about what happened. :)

Do you know if you have Hashi's, BTW? Have your antibodies been tested?

You won't want to hear this, but consider that rT3 might just be a red herring!!

But first...

TSH was just over 5, FT4 good, FT3 a little bit low).

This suggests hypothyroidism/ undermedication, these levels are far from textbook!

When medicated TSH should be 1 or less, without medication, close to 2.

Many GPs won't initiate medication below TSH 10 by which time patients are struggling badly

Weight gain is a hypo symptom

We need actual results with reference ranges to evaluate your condition

Vit D, vit B12, folate and ferritin need to be optimal to support thyroid function

We need to test antibodies for signs of Hashimoto's disease

it may be that your T4 to T3 conversion is poor.....high FT4 with low FT3

How much of this did your medics investigate our?

My symptoms are absolutely crippling, and absolutely consistent with severe hypothyroidism

I think you have self diagnosed!!

Your extreme exercise and severe dieting most likely contributed to your problem and when you stop this routine your weight will probably increase again. If the weight gain is caused by hypothyroidism correct medication a huge part of the solution.

Getting my bloods to completely normal levels has had no effect on my health whatsoever, if anything I'm worse than ever now

If by completely normal levels you mean that your labs are in range then that is not the answer. You need your levels to sit on a point within the range where you feel well. I suspect this is at the root of your problem. Medics knowledge of thyroid disease is sadly very limited....either NHS or private, that is why well over 120,000 people have arrived here desperately seeking help. Several years ago that was me too, here with support and much reading I then found the answers medics failed to discover.

T3 is the active thyroid hormone and is required by every cell in the body in an adequate and constant supply. It must be transported, via T3 receptors, from the blood to the nuclei of the cells where it becomes active.

Low cellular T3 results in poor health.

FT3 is the important lab not TSH as medics claim.

Your rT3 is possibly high because T4 has not been cconverting effectively to T3 so that the T4 level has become raised and eventually converted to rT3.

I quote from excellent advice from on this forum, It's just that when FT4 is too high, more is converted to rT3 and less to T3 as a safety valve to stop you becoming over-medicated.

There is no 'optimal' number for rT3, it's not something you need. It is inert and doesn't stay in the body for more than two hours, when it is converted to T2. It doesn't cause symptoms.

There are many, many causes of high/over-range rT3, and only one of them has anything to do with thyroid. And, that is when FT4 is too high.

Time to make changes!

Just a few thoughts, hope they help.

jgelliss profile image
jgelliss in reply to DippyDame

DD may I say your a young 76 year young. Your contributions are very sound and valuable.

DippyDame profile image
DippyDame in reply to jgelliss

Don't be deceived.....but thank you!!

jgelliss profile image
jgelliss in reply to DippyDame

All I can honestly say your your responses on the forum are very vigorous and very spirited. That's more youth than some of the youths I know. Keep going strong. Your very inspirational.

It used to be thought rT3 blocked T3 binding to receptors by binding to the receptors itself but it was found rT3 doesn't bind to receptors. rT3 does seem to inhibit type-2 deiodinase which converts T4 to T3. This would be reflected in low serum T3 levels.

It might be more profitable to look at the things that can elevate rT3 such as starvation, depression and severe chronic illness. If all that is excluded the other option would be to trial a little liothyronine. I'd try to avoid suppressing your TSH if possible.

JonnyA, I don't have an answer, but I'm pretty much in the same boat as you. I broke myself dieting. I did really well for around a year on a paleo diet but then stopped loosing weight. So I reduced more carbs and more carbs until I was on a very low carb diet. We need carbs to run our metabolisms. When I went very low carb I felt awful but people said you had to power through it and it should all be miraculous after 2 weeks. Well it wasn't and I've never recovered. I lost all my energy and my fitness and regained all the weight and then doubled it. I've been like this for 8 years now. It's soul destroying, I know how you feel.

I am looking into how the diodinase enzymes affect things. I know I have a genetic fault with the Dio2 enzyme, so that means I have a disadvantage converting T4 into T3, so I started adding T3. Apart from the first day I've felt mostly worse on T3. Each time I increase my dose I feel good for the day and then back to where I was or worse. The only explanation I could find is that my FT4 was too high and facilitating this conversion to rT3 so I reduced it from 125 down to 75 Levo a day. But so far I just feel worse. I'm waiting for the latest blood results to come through. I think rT3 is stealing my T3.

Have you read Paul Robinson's blog posts? He's also written 3 books on recovery that are worth buying and reading. A long-term sick thyroid patient he had to solve the problem for himself and has been well for a long time now. He talks about rT3, not in that vein that it blocks any receptors but that it just steals our T3.

The web site has quite a lot about rT3 and the diodinase enzymes.

You are not alone. But we are the unusual cases so not many can understand how we feel. It's horrible.

I think rT3 is stealing my T3.

What exactly do you mean by that? It sounds very strange. How can anything 'steal' your T3?

By converting it to rT3. I'm taking T3 and T4 but not getting benefit so I think too much is being converted to rT3.

One of the diodinases converts T3 to rT3 (I think, or did I get that wrong and it converts T3 to something else?). Either way, my T3 is not available so I think of it as being stolen.

I'm sorry, but you did get that wrong. Only T4 converts to rT3. Both T3 and rT3 are converted to T2.

If you are taking T3 it has to be available. Or else, you're either not taking enough or you're not absorbing it well - either at gut level or cellular level. But, neither have anything to do with rT3. If you 'think of it' as being 'stolen', you might know what you mean, but I doubt anyone else does. :)

Just had a thought... It's not that T3 converts to rT3, but if your FT3 is too high, even more T4 will be converted to rT3 to attempt to lower the amount of T3 in your system. Maybe you were getting confused with that?

SlowDragon profile image

Looking at previous post you’re only taking 5mcg T3 at moment….or are you taking two or three 5mcg doses of T3 per day?

How long have you been adding T3

What are your most recent test results

Bloods should be retested 6-8 weeks after each dose change

Are you gluten and dairy free? Need optimal levels of b12, vit B12 d, ferritin and folate. Also need to supplement zinc and selenium. All this should help conversion of T4 to T3

Hi Jonny, I can see why you’re looking at rT3 but just wondered what exactly are your latest blood results?

shaws profile image

The following is by a scientist/researcher/doctor and who would never prescribe levothyroxine. Dr Lowe who was an Adviser to TUK (deceased through an accident).

The following may also be of interest:-

He stated Levo became the No.1 due to payments being made to the medical professionals (in USA I believe).

He prescribed the very original replacement which is NDT = natural dessicated thyroid hormones made from animals' thyroid glands from 1892 onwards which saved lives from then on.

If you are on levo only, and have high rT3, that means that your body is turning more T4 to rT3 than to free T3. If you are on mostly levo and a little T3, there is also plenty of T4 which much be converted to either free T3 or rT3. So, as a result, your metabolism decreases and hypo symptoms appear. As you point out yourself, it´s likely that severe calorie restriction caused this. The body is trying to preserve energy to prevent starvation. When the body needs to preserve more energy - be it because of illness, calorie restriction, inflammation just to mention a few - it will turn more T4 to rT3 to decrease metabolism. The ensuing hypothyroidism is caused by low FT3 levels since less T4 is converted to free T3. So, high rT3 is the result of the body´s instinct to preserve energy in some cases, not the cause of it. Westin Childs is a former doctor of osteopathy who is also selling his own very pricey supplements, including supplements to treat high rT3. In my opinion, he has not kept up to date with new research. The same goes for the STTM. The theory used to be that rT3 and free T3 are antagonists and compete for the same cell receptors. Newer research has debunked that myth.

Nobody questions the existence of rT3. The controversy is: does it block free T3 or not? The skeptics say no.

You are of course free to believe what you want. In case you believe that your high rT3 is making you hypothyroid, why not go off levo for a while and take T3 only? That is the method suggested by practitioners treating rT3 dominance.

JonnyA profile image
JonnyA in reply to

“The role of rT3 is to decrease metabolism when the body needs to preserve energy, for one reason or another.”

Is this still generally accepted? That RT3 doesn’t necessarily block FT3, but that it acts to slow down metabolism regardless?

In that case, would that render FR3:RT3 ratio a relevant diagnostic. According to what I read, the optimal ratio should be 20 or higher. Mine is currently 5.5.

in reply to JonnyA

I recently read that hibernating bears have very high rT3 levels. That is logical as they don´t need as much energy while they are sleeping. But, when they wake up in spring, their rT3 levels decrease as their free T3 levels rise. If the rT3 dominance theory was right, bears would need to be on T3 only to correct that...! There are many cases when rT3 rises - in case of serious sickness, calorie deprivation, inflammation, untreated diabetes 2...just to mention a few.

Dr. Childs is right when he says that very low calorie diets and yo-yo dieting can cause high rT3 as the body perceives those as starvation and rT3 is a survival mechanism.

Also, the rT3 dominance theory - that you flush out high rT3 using T3 only during 8-12 weeks and then try to add levo again - has one flaw: if you don´t identify and correct the underlying cause, the problem is going to come back once you add back levo.

So yes, rT3 acts as a break on the metabolism when the body needs to lower it. I don´t think anyone questions that. But, taking levo is not the cause of high rT3. If you have high rT3 after dieting, more rT3 will be made from the levo you take, but it´s the calorie deprivation that is the cause of your high rT3, not levo as such.

JonnyA profile image
JonnyA in reply to

Thanks for that. In the short-term at least, are you of the opinion that medicating with T3 only (at the right level) will reduce RT3 and help remove that brake on the metabolism? Clearly there needs to be a good ‘exit plan’ in place, but at this moment in time I am just desperate for symptom relief.

FancyPants54 profile image
FancyPants54 in reply to JonnyA

What do you mean by "exit plan"? Quite a few people have to treat their hypothyroidism with T3 only. All the time.

in reply to JonnyA

Well, of course, if you remove the T4, the body does not have any raw material to create rT3 from. But, as I said, you need to address the underlying issue(s) in order for it not to rise too high again. If diets and too much exercise caused you to have high rT3, you would need to avoid diets in the future and exercise more moderately. I especially think that low calorie diets and overexercising is very bad for hypos...if the body is not getting enough energy with all that exercise it will only lower your metabolism further.

JonnyA profile image
JonnyA in reply to

Presumably this would only apply after you ceased T3-only medication?

Does T4 need to be surpressed entirely in order to completely eliminate RT3? I haven’t been able to find much by way of dosing guidelines for such an eventuality.

in reply to JonnyA

Dr. Childs recommends either going off T4 completely or taking a much lower dose (25-50 mcg daily). He says that is usually enough to lower rT3 levels.

Yes, the problem that made rT3 rise in the first place would come back if, after some time on T3 only, the underlying issue is not corrected.

humanbean profile image
humanbean in reply to JonnyA

To create rT3 your body needs T4. If you don't take T4 and your thyroid is very damaged you might have extremely low or zero levels of T4. If you have zero, or nearly zero T4 then your body simply cannot make reverse T3 because T4 is the raw ingredient for creating rT3 (and ordinary T3).

T3 cannot be converted to rT3, and nor can rT3 be converted to T3. The thyroid does create about 20% of the body's T3 directly [Edit: when it is healthy enough to do so] rather than from conversion from T4.

Note that greygoose is on T3 only and has T4 levels of zero all the time. But quite clearly her brain still works extremely well! :)

Note that one cause of high rT3 which I don't think anyone has mentioned is having high cortisol. And high cortisol will lower TSH.

DippyDame profile image
DippyDame in reply to JonnyA

JonnyA It sounds as if you can only focus on rT3 right now...and that will get you nowhere!I'm high dose T3- only and never in all the years (20+) since I was diagnosed with thyroid disease have I paid any attention to rT3. Any rise is transient then it is eliminated as has been explained to you.

Until you start focusing on your lifestyle, the nutrients essential to thyroid function and critically, the active thyroid hormone T3, then you will be stuck up a creek without a paddle.

I'm sorry I don't mean to be rude but I'm ancient and often outspoken and right now you need to change your mindset

I suggest you start by reading what greygoose wrote to you at the top of this post....her experience and knowledge is vast.

This disease can be a huge challenge, not least because most medics are poorly educated in the subject and most endos are diabetic, not thyroid, specialists.

To help further we really need full thyroid labs -

TSH, FT4, FT3, vit D, vit B12, folate, ferritin and antibodies TPO and Tg

You are very possibly undermedicated, possibly wrongly medicated and most likely exhausted by the whole thing, which makes everything seem very much worse than it is.

You are entirely correct to aim to educate yourself - I would most likely be dead now if I hadn't done just that - but take a deep breath, focus on what is important and learn from reliable sources.

Take care and good luck!

in reply to DippyDame

I agree with everything you say! It´s unfortunate that many websites have not updated their info about rT3, but still maintain that rT3 dominance is a problem that should be solved using T3 only. They make it sound like a much bigger problem than it is, and people sometimes get the wrong focus because of that.

JonnyA profile image
JonnyA in reply to DippyDame

I suspect I, myself, will be dead soon if I don’t get some relief shortly. If you sense desperation in my words, that’s because I’m absolutely desperate.

My focus is where it is right now because I’ve tried practically everything else, and no questions have been answered and no relief secured. At the very least, I’d want to eliminate RT3 as a potential issue. If I can get to healthy T3 levels and low RT3 and things are still rubbish, then it’s not that. Fair enough, move on, if I can.

But given the confusion which seems to prevail on this matter I can’t afford to walk away from this hypothesis without confirming 100% first-hand.

If that mindset’s wrong then so be it; it’s the only one I’ve got. I have to trust my own gut as I’m running out of time.

DippyDame profile image
DippyDame in reply to JonnyA

We are no strangers to desperation here....often real, raw, desperation! So we can empathise...

Those of us who have been there and found answers now try to use our experiences to help others who find themselves in similar circumstances.

I’ve tried practically everything else,

Are you absolutely sure?

There is the last resort- T3-only

Have you considered this?

I've clearly said more than enough and I'm sorry if I've upset you so I hope now that you find the answers you seek but bear in mind as you continue your journey that an open mind is a vital part of any research.

JonnyA profile image
JonnyA in reply to DippyDame

First, off, no - you haven’t upset me so no need to apologise. I appreciate that you’re trying to help. I’m just trying to give you some more context to my situation and how I arrived here.

T3-only is exactly my next step (in fact I’ve already started). Either way, that’s going to get me to a place where my T3 is good and RT3 is low, so it at least removes other variables.

All I can do beyond that is hope and pray. If that’s not the answer, I don’t really know where to go next. Still, one step at a time eh?

DippyDame profile image
DippyDame in reply to JonnyA

Good luckI've been T3-only for a few works for me.

rT3 when dosing with T3-only will naturally fall off....for high levels of rT3 to exist there needs to be high T4

On T3-only both TSH and FT4 will fall

It takes time so be patient.

in reply to DippyDame

Are high T4 really required in order for there to be rT3? A healthy thyroid makes mostly T4 which is converted to FT3 and rT3 (some sites say in a 60-40% ratio, others in a 50-50% ratio), so there is always some rT3 around as long as there is some T4 in the system. rT3 is not a problem in itself, it´s normal to have some rT3 - even if your T4 levels are not particularly high.

DippyDame profile image
DippyDame in reply to

Ooooops, yes, I explained that badly!

Should have said ...for raised levels of rT3 to exist

Thanks for picking me up on that.....dippy moment!!

greygoose profile image
greygoose in reply to JonnyA

I think it absolutely crucial to but in here and say that it will be the increased levels of T3 that will restart the metabolism, NOT the reduced rT3. rT3 is inert.

Is this still generally accepted? That RT3 doesn’t necessarily block FT3, but that it acts to slow down metabolism regardless?

NO! That's not what she meant. rT3 does not act to slow down metabolism. It is the reduction in T3 that slows down metabolism. And T3 drops because more T4 is being converted to rT3 - for whatever reason - and therefore less to T3.

Hi Jonny,

I can relate so much to what you've said. I started with my thyroid issues in 1979. I had high reverse T3 issues which were found out through testing in 2003. God only knows how long I'd been like that, like you, I've always been a high achiever and not one to let anything hold me down for long. It was a homeopathic endocrinologist in Bocan Raton Florida that was the main Dr that helped me on my road to recovery. I too work better on high protein low cabs and regular workouts. It took about a couple of years to get my reverse T3 down as it took time to change my lifestyle.

The second article you posted, was how it was explained to me. Unless you've had reverse T3 issues, you have no idea how sick it can make you feel. Even though, I did the gym 3 to 4 times a week I had chronic inflammation and high cortisol.

The doctors both were of the opinion that my stressful work contributed to this as well as me being a poor converter from T4 to T3. Amour thyroid was the medication that has helped me the most.

I ended up selling my business and got into a slightly different type of business that was easier and far less stressful.

Endocrinologists can contribute to the problem as the current trend in relying on the TSH for an accurate picture of what's going on with your thyroid is nuts to say the least and in the UK my experiences with endocrinologists private or NHS have been disappointing to say the least. In the states most endos specialize in diabetes as that's where the money is. I've come to the conclusion that what is know about the thyroid and reverse T3 can be written on a postcard.

I do my own diet based on what works for me. Meat, fish, chicken, eggs, veggies, fruit, greek yogurt, gluten free oats and whey protein smoothies. All food and drinks have to be clean - meaning, if it has anything in it that I can pronounce, then I don't drink or eat it. Be careful of bottled flavoured waters, they often have hidden ingredients that I don't do well with. Wishing you all the best on your journey and if I can be of help, you can always send me a PM.

JonnyA profile image
JonnyA in reply to Me1157

Thank you for taking the time to share this. May I ask what kind of T3 dosage you required to get you feeling better, and what your RT3 levels were like when you first tested for them?

Thanks! :)

Me1157 profile image
Me1157 in reply to JonnyA

Sorry, I don't remember the numbers as this was back in 2003. I may have the old blood work back in Florida, but I'm in the UK until my hubby's health improves. All I remember is was it was very high and one of the highest that the Dr had seen and it was the same with my antiboides. The Levo with T3 combo didn't work for me. The amour thyroid (NDT) has both T4 and T3 in and has worked best for me since 2003.

BrynGlas profile image
BrynGlas in reply to JonnyA

I think that you would be best introducing T3 to your Levo, on a really low dose and increase slowly.

If you go up in dosage too quickly you could feel much worse very quickly. I tried going too high too fast. I didn't do it again!

What an interesting post and replies.

As other have said, we have not seen your latest results and ranges. How are your vitamins?

Also I think 4 years is a short time to sort out a obviously difficult thyroid problem. You say your TSH was high for a long time and expect you have since had many changes of dose. There is a lot of damage that needs repairing. It can take a long time.

What do you take now and for how long?

I just edited one of my previous posts but wanted to point out one thing to avoid misunderstandings. What I saw now is: "When the body needs to preserve more energy - be it because of illness, calorie restriction, inflammation just to mention a few - it will turn more T4 to rT3 to decrease metabolism. The ensuing hypothyroidism is caused by low FT3 levels since less T4 is converted to free T3. So, high rT3 is the result of the body´s instinct to preserve energy in some cases, not the cause of it".I thought this was an important distinction to make, as I fear my previous post was ambiguous. What is important to stress is that low FT3 levels cause hypothyroid symptoms, and not rT3 in itself since it is inactive and doesn´t stay very long in the body.

JonnyA profile image
JonnyA in reply to

Thanks for the clarification. Reading up on more sources which align with the general consensus on here; ergo that RT3 cannot block receptors but rather that it is D2 or D3 (I've done so much reading that I've consumed myself) that do the blocking; D2 / D3 being the enzyme which converts T4 into RT3.

If that's the case, does the suppression of T4 also suppress D2 / D3. Presumably, if there is no T4 those enzymes have no role to play or reason to exist, but I appreciate that may be an oversimplification.

in reply to JonnyA

I am sorry, I cannot answer your last question, but I do think that Tania Smith´s articles on the Canadian site are a bit complicated for laypeople...with some time and effort you can manage to decipher what she is saying, but you don´t always have that time or energy...a shame, as she raises a lot of important subjects of great interest to many thyroid patients.

tattybogle profile image
tattybogle in reply to JonnyA

"If that's the case, does the suppression of T4 also suppress D2 / D3. Presumably, if there is no T4 those enzymes have no role to play or reason to exist, but I appreciate that may be an oversimplification"

Interesting question JonnyA . must admit , i have the same difficulty with keeping a clear picture in my head re. which deiodinase is doing what /when. There are two pictures on replies to this post which help me remember which does what

Have you tried asking Tania S. Smith (author , blog) a direct Question ?

.... either via comments at end of her blog posts , where she does seem to answer Q's , or i think there is also a facebook group where she answers questions.

Two of Tania's best blogs on subject are ;

Hi JonnyA

I was in a mess when I found this forum. I’m lucky - I seem to have been able to get well with the easiest option, just Levothyroxine. But the folk further up the string have given you an insight to how you may get yourself back on track.

Best thing I did was take the advice here and realise my GP and every other GP I have come into contact with since knew little to nothing and were dangerous. The old adage a little knowledge is a very dangerous was never so true.

Looks like you’ve had some superb advice here, but come back with your results (with ranges) and take advice. Re vitamin levels and such everything works together and you will need vitamins to be optimal not just in range or that awful word ‘normal ‘ (which is meaningless).

I’ve gone gluten-free, that has helped me. Read my profile to see how I got to a full replacement dose of Levothyroxine even though I was ‘in range’ at every juncture. I know your path will not be the same if going down the T3 route, but you will come upon similar ignorance and resistance and it will give context.

Stay with us and let the forum help you. I was suicidal when I joined the forum- I’m angry with the medical profession for the ‘crock’ they fed me (still am) but now empowered and well as a result of finding this forum.


Elevated RT3 is problematic as can stop thyroid meds from working effectively. The trouble is in evaluating exactly what has caused the elevated RT3 because if it isn’t through over-medication, changing meds/doses won’t help.

I remember telling you I was surprised when you introduced T3 before FT4 was fully optimised. This is a reason for elevated RT3 if your body didn’t need it as it will not tolerate levels of thyroid hormone it can't use so converts it to an inactive metabolite.

T4 is converted to RT3, and T3 is congruently converted to inactive T2. You can not force your body to utilise higher amounts of any thyroid hormone than it can tolerate, and because you have done this you do not know if you are a T3-only person or someone who requires both hormones.

You seem to have reset how your body utilises thyroid hormone through extreme dieting. I can only suggest you medicate thyroid hormones that suit and consume adequate calories that are required for cellular T3 uptake. Also as hb mentions above your cortisol levels could be sky-high and putting a big spoke in the works, ie another reason for elevated RT3.


You mentioned the deiodinases. This link may help explain how T4 & T3 become inactive 😊.

greygoose profile image
greygoose in reply to radd

Elevated RT3 is problematic as can stop thyroid meds from working effectively.

How does it do that?

radd profile image
radd in reply to greygoose


Deiodinase type 3 is the enzyme that rises to dominate in states of severe illness and /or excess T4 and/or excess T3.

Having elevated RT3 by default means D3 is up-regulated and it is D3 enzymes that block T3 from entering the cell’s nucleus. So it is actually an up-regulation of D3 that causes our meds not to work but I used elevated RT3 which is the well known byproduct that members more easily recognise.

Then when T3 becomes low, D1 becomes down-regulated and cannot efficiently clear RT3 from blood. It also loses some efficiency in conversion of RT3-T2 conversion and T4-T3 , so reducing T3 levels further.

D3 can still dominate in the presence of low RT3 when there is not enough T4 to turn into excess RT3, and so still create low T3 levels through the conversion to inactive T2.

Most is explained in the link I posted above and a little bit more here.

in reply to radd

So, to sum up, taking T3 only is not a cure for high rT3, as claimed by some alternative health practitioners as well as the STTM? I believe that is what the OP asked.

JonnyA profile image
JonnyA in reply to

Yep, exactly that. If my raised RT3 is merely a marker for elevated D3, which is the real problem, then how do I solve that problem?

Thank you! :)

in reply to JonnyA

I have no idea, I am no expert on rT3. Hopeful, others with more knowledge will chime in.

radd profile image
radd in reply to


in reply to radd

Good to have that confirmed, as that myth is still very much alive on many blogs and thyroid forums.

PPower profile image
PPower in reply to

PurpleCat71, that is NOT what STTM says. They say that you can lower your rt3 by using only T3 but you MUST find your root cause of how you got that high rt3, otherwise, you've accomplished nothing by just getting the rt3 number down.

greygoose profile image
greygoose in reply to radd

So it is actually an up-regulation of D3 that causes our meds not to work but I used elevated RT3 which is the well known byproduct that members more easily recognise.

And thereby perpetuating the myth that it's the rT3 itself that is causing all the problems, which others have spent hours posting on here trying to explain isn't the case.

JonnyA profile image
JonnyA in reply to greygoose

Even more frustratingly for me is that there is plenty of, presumably misguided, information about how to deal with RT3, and then a few more recent articles (as outlined by many of you on here) pointing out that RT3 is not the active threat, but potentially a mere calling card.

What I can’t find anywhere, even on the excellent if slightly bamboozling website, is how you’d go about treating excessive D3 levels. I just can’t find anything.

greygoose profile image
greygoose in reply to JonnyA

Probably because nobody knows. There is still such an awful lot to be learnt even by the genuine thyroid experts. Medical science is far from knowing everything about thyroid.

Has someone on here - I confess I'm totally lost in this thread, now - given you a check list of possible causes of rT3? Just in case they haven't, here's one:

* Chronic fatigue

* Acute illness and injury

* Chronic disease

* Increased cortisol (stress)

* Low cortisol (adrenal fatigue)

* Low iron

* Lyme disease

* Chronic inflammation

* Selenium deficiency

* Excess physical, mental and environmental stresses

* Beta-blocker long-term use such as propranolol, metoprolol, etc.

* Physical injury is a common cause of increased RT3

* Viruses, such as flu

* Starvation/severe calorie restriction

* Mistreated diabetes

* Cirrhosis of the liver

* Fatty liver disease

* Renal Failure.

* Fever of unknown cause

* Detoxing high heavy metals levels

That's not a complete list, but do any of those ring any bells - apart from 'severe calorie restriction', of course?

But, I don't think you've given us your FT4 reading yet, have you? Is it high?

JonnyA profile image
JonnyA in reply to greygoose

Calorie restriction is the obvious one; none of the others apply to my knowledge.

My most recent FT4 reading was 10.6, but this was 2 or 3 weeks after dropping T4 and going T3 only (T3 was 5.03). The highest my T4 has been, and this was on levo, is 19.5.

greygoose profile image
greygoose in reply to JonnyA

Sorry but those numbers mean nothing without the ranges. But, 19.5 does sound high - high enough to raise rT3.

And, do you know what it was when you first found out you had high rT3?

JonnyA profile image
JonnyA in reply to greygoose

My FT4 was 10.6 [12-22] the day after that RT3 test was taken (as in sample drawn). Presumably RT3 will have been much higher before.

I can’t stress enough, I feel profoundly ill.

greygoose profile image
greygoose in reply to JonnyA

OK, so it was probably not excess T4 that was causing it.

But, what was your FT3 level? I don't think you've mentioned that.

JonnyA profile image
JonnyA in reply to greygoose

It’s a couple of posts up, but it was 5.03 [3.1 to 6.8].

greygoose profile image
greygoose in reply to JonnyA

But, was that on levo only? Or T3 only?

JonnyA profile image
JonnyA in reply to greygoose

At that point, it would have been about 3-4 weeks worth of T3 only.

greygoose profile image
greygoose in reply to JonnyA

OK, so that doesn't tell us how well you were converting. Never mind. The important thing now is that you are on T3 only, presumably sorting out your nutritional deficiencies? Eating more and exercising less. So, now, it's a question of having patience. Nothing happens rapidly with hormones. It's going to take a while for your body to fully trust you again, you have to regain its confidence that you're not going to starve it again.

in reply to JonnyA

I would assume that the solution is the same: identify the cause of your high rT3. In your case, it seems likely that was strict dieting and too much exercise which puts the body in starvation mode. So, if you want to solve the problem, you need to fix whatever went wrong in the first place. You need to eat enough calories, enough good fats, enough protein, enough low glycemic carbs. And you should exercise but don´t overdo it. If you find a way to eat a balanced diet and add some exercise to that, your D3 should logically be down-regulated and that should in turn lower your rT3 over time. Remember, it´s not a quick fix. The problem is that many blogs, websites and forums have not been updated to take account of newer research.

radd profile image
radd in reply to greygoose


The two go together. You can have elevated D3 without elevated RT3 but you can't have elevated RT3 without elevated D3 😊.

JonnyA profile image
JonnyA in reply to radd

But can you have D3 without RT3? In my case, I could presumably eliminate RT3 through T3 only meds, therefore suppressing T4 which is needed for RT3 to exist.

But then I’d still be left with high levels of D3 and symptoms of hypothyroidism, wouldn’t I? Eliminating the product won’t be effective if it’s the source that is the problem.

But how do you eliminate the source, i.e. D3? Or does D3 disappear if there is no T4?

in reply to JonnyA

If you look at radd ´s earlier comment, it says:Deiodinase type 3 is the enzyme that rises to dominate in states of severe illness and /or excess T4 and/or excess T3.

I interpret this to mean that D3 will not disappear without T4 as both T3 and T4 affect D3.

Just to give you some friendly advice: I think you should stop obsessing about rT3 and D3. As far as I know, D3 cannot be measured, at least not outside research facilities, so you will have no way of knowing what happens to it. My suggestion would be to focus on a healthy diet, enough exercise, and getting your thyroid hormone medication right. That would be the first step.

radd profile image
radd in reply to JonnyA


D3 stands for deidinase type 3 enzyme(D3). There is also type 1 (D1) & type 2 (D2) and these are control points that determine cellular activity or the deactivation of thyroid hormone.

Every one has them and each enzyme has its own job but is influenced differently by different physiologic conditions so dictating different tissue levels of both hormones, meaning there are an infinite amount of variables.

You mean can you have up-regulated D3 without elevated RT3, and the answer is yes if there is inadequate T4 to convert. As already explained to gg, the role of D3 is two-fold converting T4 to RT3 but also T3 to an inactive form of T2 called 3,3′-T2.

Yes, you need to find the root cause(s) which can be impossible so we concentrate on the optimising everything and clean living, and things hopefully sort themselves out.

greygoose profile image
greygoose in reply to radd

That's irrelevant to what I was saying.

radd profile image
radd in reply to greygoose


Then I don't understand what you are saying🤣

in reply to radd

I remember telling you I was surprised when you introduced T3 before FT4 was fully optimised. This is a reason for elevated RT3 if your body didn’t need it as it will not tolerate levels of thyroid hormone it can't use so converts it to an inactive metabolite.But, if the OP started on T3 before his FT4 was fully optimised, how could this be the reason his rT3 is elevated, given that rT3 is made from T4? It´s only T4 that gets converted to an inactive metabolite, not T3.

radd profile image
radd in reply to


Because it is not directly about the RT3 but the deiodinase enzyme type 3 (D3) that drives it and that will also convert T3 to an inactive T2 by default.

(I just used 'RT3' because the O/P was relating to it and intimated he wasn't familiar with the deiodinases.)

In fact Tanya Smith says D3 even favours converting T3 to inactive T2 and so this will occur even in the presence of low or non existent T4. Hence why some people's T3-only meds sometimes don't work.

Read the links I have supplied above that detail how D3 influences both T4 & T3 hormones and in what circumstances. Really interesting 😊

JonnyA profile image
JonnyA in reply to radd

Interesting post, thank you. So if D3 is the issue, and presumably suppressing RT3 won’t suppress D3, then how does one deal with D3? Can it even be tested?

radd profile image
radd in reply to JonnyA


Finding the root cause is the whole issue sadly, and it can originate from multiple sources so impossible to eliminate all unknown possibilities. That's why the general consensus is to optimise iron, nutrients, reduce inflammation, live cleanly and hope a lot 😊

FancyPants54 profile image
FancyPants54 in reply to radd

This is what I was trying to describe above when I said I felt as if my T3 was being stolen but I was told that couldn't happen. But I knew I had seen somewhere that it was possible for the body to take T3 and convert it to something inactive and this was it. So I wasn't wrong. Just worded it badly and didn't remember the detail.

Well, it can't happen. Not if you use the word 'stolen'. Nothing can 'steal' your T3. Using the right words is so very important. :)

I am trying to do this right now. It's hard. I've reduced my T4 by 50mcg a day now, currently on 75. And increased my T3 but I'm still not feeling benefit. It really feels as if my T3 is not getting into my cells. Just done bloods and my T3 is still less than 50% through the range! FT3 is not out of the bottom of the range. I could really do with seeing some improvement soon. I'm so tired and fed up.

So what dose daily are you on now, Levo and T3?

I really didn't feel that I was on the right medication until I had building up my T3 very slowly since 2020, but then last summer I noticed that my hair was regrowing.

Are you seeing an Endo? Or did you buy your own T3? If you wanted to increase your T3, can you get more T3, or are you at the mercy of a medic?

I reduced my Levo finally to 50mcg daily. When I was feeling much better I just thought one day that I would stop Levo entirely. I was prepared to go back to Levo, if I had to, but nothing changed and I stayed on T3 alone.

I’m currently on 75 Levo and 50 Lio. I see a private endo so I have a script for Thybon Henning Lio. I have plenty.

My hair and skin are terrible. I’ve lost so much hair, and what I have left is so fine it’s like cobweb. It’s also lifeless. Inert. My skin is terribly dry and itchy.

My FT4 is -22% of range on my last test, which was taken when dosing 45 Lio. But I suspect it needs to go even lower to get the T3 into my cells.

Thanks for sharing your story, I appreciate it. It’s heartening to hear you’ve overcome those demons and you’re feeling much better now.

May I ask what your ‘high dose’ is, out of interest?

I take 4 x 25mcg Tiromel daily. What dosage are you on? I only assume it is a high dose because most people who disclose their dose of T3 on the Forum take a lot less! I do tend to not mention it! LoL

I feel great, temperature and pulse are fine as is BP. My hair started growing back last summer and I am now losing weight, which has always been my goal. I appreciate your problems with weight, because going up from size 12 for my whole adult life, I went up to size 22 after diagnosis and I just wanted to hide myself away. I am not so large now, thank the Lord.

Your problems sound a lot worse than mine, but since 1999 I have had the feeling that I wouldn't ever get to be 'right' again. I think we can all empathise with you..

In 1999 was just told Levo or nothing, I had no option.

When asked to help me with a trial of T3, my GP told me I was not to say those words again because T3 was an illegal drug. That is the sort of knowledge that the majority of GP's and some Endocrinologists have. So sad.

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