Thyroid UK
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Could this be reverse T3 clearance?


To cut a long story short, I was originally prescribed T3 many years ago and was well. A few years ago I was switched to levo and was not well. I have tried NDT and also NDT/T3 combo, eventually settling for T3 only and now feel much better.

I gradually increased my T3 dose and reached 125mcg at which point I was feeling pretty good - not 100% but so much better than on T4 of any kind. Last night, about 3 hours after my bedtime dose of 25mcg, I woke with sweats and a racing heart. Both are not something I typically experience. I have been on 125mcg for a while so I wasn't expecting this.

I was wondering if the reverse T3 had finally cleared and I was finally getting a shed-load of T3 into my cells all of a sudden. I did feel like I was hyper, from the descriptions I've heard of hyperthyroidism (from over-replacement). I slept only about 2 hours and while I was lying there I felt like I had just sprinted round the block several times.

Does anyone have any personal experience of this? I have read that this whole 'rT3 blocking the receptors' is a bit of a myth so I'm not quite sure what to believe.

As a result, because my body is clearly trying to tell me something, I have reduced my dose to 12.5mcg four times a day. I feel tired today but I am sure that is at least partly due to lack of sleep and a crazy day at work. I am going to stick with 50mcg for a few days and get some rest and see how I feel after that. My heart rate is much better today and much more regular again. My temperature was also nearly normal this morning, possibly from the clearance of that rT3. Even on 125mcg my temperature rarely reached more than 36.5 on a good day, unless I was ill. Today it was 36.8 :)

Anyway, I would appreciate hearing from anyone who has been through this rT3 clearance, mythical or not. I do feel there is something in it even if it isn't the whole story.

I know I'm not well known for my brevity, but this isn't nearly as long as it could have been :D

Carolyn x

19 Replies

All I can tell you is that I started T3 only on 18th Feb this year and prepared myself for many weeks of clearing T4. By 19th March I noted in my record book that I felt very light and airy and did not need as much T3. I lowered my dose for a few days . Two days later I was due for a blood test and interestingly my T4 was down to 1.1. In other words I had virtually cleared it in about 4 weeks. I then looked back in my records and found I had a night of sweats and palpitations just before I began to feel better, so I think mine was a modified version of what you have just been through. Hope you now feel much better. xx


Thanks. I am calmer today. Hopefully, once I get some sleep, I shall be feeling much better :)


Hi Carolyn,

So sorry you are having difficulties and are feeling unwell. I think that this sort of thing is one of the most frustrating of this illness - you are sailing along nicely (well sailing along anyway) for weeks, months and sometimes even years on the same medication and dose and all of a sudden, for no apparent reason, it all goes haywire again and you are left wondering what has happened and why. This illness is so very unpredictable and sometimes I think if we, the sufferers, cant understand it 100% with all out research and talking amongst each other is it any wonder that anyone but the most dedicated of doctors dont understand it fully either.

Cant help with the RT3 thing as I have never experienced it but wish you well in finding your answers.

Moggie x


Thanks Moggie. I'm really hoping this is just because the reverse T3 has cleared and now my body is actually using ALL that T3, lol. I think it made me rather hyper but then I think 125mcg would for most people. I was very surprised I needed that much so perhaps this is a good thing. Maybe when I have had some sleep I will feel much better on only 50mcg. It will save me a small fortune! According to some literature I have read, it appears that this clearance of the receptors should happen round about now. Fingers crossed this is the first step to getting properly sorted out! I may even be able to add back some T4 eventually too :)

I'll let you know how I get on.

Carolyn x


Do you feel you need to add T4? I ask because Naamisue was always saying how she felt that she would benefit from adding T4 to her T3 but never could as her body rejected it. I was always puzzled at her saying this and could never quite understand it and all she would say was how she felt her body actually needed the T4.

I really hope your theory of the RT3 clearing out of your system is right and I totally agree that 125mgs of T3 in quite a lot for a person to be able to handle, pocket wise and health wise.

Moggie x


I don't think I need the T4 yet. I really don't get on with it at all. It makes me quite ill but perhaps once I have sorted everything out and have been well for a while, I may be able to add it without problems. I do think we need it normally because otherwise why would we produce it? Then again, we're not exactly normal on the thyroid front are we? Lol.


Hi Carolyn, I was just wondering what you meant by 'clearance of rT3 from receptors should happen about now'. How long does it normally take? I have just posted a question and think I may have been through something similar to you. Would be really grateful for your reply. Thanks! :-) xx


I feel totally ignorant on the reverse T3 front. There appears to me to be far too much "that seems to make sense" and far too little hard evidence. That is not saying it is irrelevant or unimportant - possibly very far from it.

The abstract below (full paper by following link at end) may have zero relevance to your question/situation but it does suggest that rT3 has some reason to exist other than as a bypass on the T4 -> T3 conversion mechanism. (Which seems so often to be claimed.)

Rapid Responses to Reverse T3 Hormone in Immature Rat Sertoli Cells: Calcium Uptake and Exocytosis Mediated by Integrin


There is increasing experimental evidence of the nongenomic action of thyroid hormones mediated by receptors located in the plasma membrane or inside cells. The aim of this work was to characterize the reverse T3 (rT3) action on calcium uptake and its involvement in immature rat Sertoli cell secretion. The results presented herein show that very low concentrations of rT3 are able to increase calcium uptake after 1 min of exposure. The implication of T-type voltage-dependent calcium channels and chloride channels in the effect of rT3 was evidenced using flunarizine and 9-anthracene, respectively. Also, the rT3-induced calcium uptake was blocked in the presence of the RGD peptide (an inhibitor of integrin-ligand interactions). Therefore, our findings suggest that calcium uptake stimulated by rT3 may be mediated by integrin αvβ3. In addition, it was demonstrated that calcium uptake stimulated by rT3 is PKC and ERK-dependent. Furthermore, the outcomes indicate that rT3 also stimulates cellular secretion since the cells manifested a loss of fluorescence after 4 min incubation, indicating an exocytic quinacrine release that seems to be mediated by the integrin receptor. These findings indicate that rT3 modulates the calcium entry and cellular secretion, which might play a role in the regulation of a plethora of intracellular processes involved in male reproductive physiology.

Citation: Zanatta AP, Zanatta L, Gonçalves R, Zamoner A, Silva FRMB (2013) Rapid Responses to Reverse T3 Hormone in Immature Rat Sertoli Cells: Calcium Uptake and Exocytosis Mediated by Integrin. PLoS ONE 8(10): e77176. doi:10.1371/journal.pone.0077176



This is interesting. I need to do some reading around to fully understand it but it is interesting that rT3 has other functions, nonetheless. I know that rT3 is important but didn't know about other functions. All I knew was that it helps to regulate metabolism, which is an important function. I also understood (perhaps mistakenly?) that too much can 'block' receptors from receiving active T3 and causing a kind of tissue resistance.

I do think this is what happened to me. Unfortunately I cannot tell if my newly reduced dose of 50mcg is enough as I haven't had much sleep yet again due to a very poorly little girl. She has a very high temperature and 'everything hurts'. I'm hoping it's not 'flu again!

I think my dose must be adequate though as my temperature 3 hours after my morning dose of 12.5mcg (instead of 50!) was rather warmer than usual at 36.7. Even on 125mcg I wasn't getting temperatures this high, until yesterday of course :D This does suggest, to me at least, that there was some sort of tissue resistance that has now resolved. Whether it was caused by a build up of rT3 or a build up of T4 that took rather longer than expected to clear, I don't know.

It would make sense that rT3 has some other function, just like I believe T4 has some function other than to just 'store' thyroid hormone for when is necessary. Quite a significant amount of rT3 is produced from T4 which makes me think. I do think there is some misunderstanding among some. rT3 isn't bad in itself. It's a higher-than-normal rT3:T3 ratio that seems to cause problems (or maybe not?) but it can also be an indicator of other underlying problems such as low iron or adrenal insufficiency.

I am hoping that one day I will be able to add some T4 back but for now T3 only seems to be the best thing for me. Perhaps when my body has properly recovered, T4 won't cause me so much grief!

Thanks for posting the paper. It just goes to show how little we, and doctors, know about the functions of thyroid hormones, and very possibly hormones in general!

Carolyn x


Hello Carolyn, I am so glad that I came on this site again today because I have just experience exactly what you have gone through. This is my story. I was on Levo for 18 years and never felt well on in, been tweaked by doctors and Endos from 100mcgs to 150mcgs and down again. Never felt well, the usual TSH low T4 17 T3 5.6 (can't be bothered to type it all out again.). So I took the bull by the horns and purchased T3 Cynomel Mexican 25mcgs and was doing fine. Started on a very low dose and built it up to 50mcgs after 8 weeks (that is upto this week). Then I decided to take the same dosage but 1 tablet in the morning 25mcgs and 1 in the evening 25mcgs. I awoke the next day with a pounding heart and irregular beats, as I tried to sleep it felt as if I was missing beats and felt uncomfortable, though I stayed calm. I had researched all this and thought wow maybe it was due to the fact I was clearing T4, reverse T3 and I had got that sudden rush. It can be quite scary and daunting, and I have stopped my T3 for a few days and I think I will restart tomorrow on very small dose again ie 25mcgs divided by 4. I like yourself do not want to go back onto T4. I was wanting to trial this so that when I see my Endo again in January she would see I have supported it better than T4. I am very wary now but don't want to stop it. Any advise would be appreciated. I know that I have spoken to you before Carolyn and would be grateful for any feedback. That was very high though I thought the amout of 125mcgs was high, I know some people do this, but it is 4 times more powerful than T4. Hope to hear from you soon and that you are feeling better. Dianex


Hi Diane.

I think I am feeling better today on 12.5mcg four times a day but it is difficult to tell because I didn't get much sleep because my daughter is poorly. I don't think I am feeling hypo, just very tired and sleepy.

If you think you have had a clearance of reverse T3 than you might find that you only need 25mcg of T3 now. It might also be because you took 25mcg at night instead of 12.5mcg. Some people get on better with smaller doses spread throughout the day so perhaps that is what works best for you.

I will let you know how I am feeling once I have had some sleep :D

Carolyn x

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Hi Carolyn yes I am sure that it is because I took the lazy way out and took the two 25mcgs tablets I was fine while doing the split doses 4 to 5 times a day. Just it can get tedious especially when you forget. So tomorrow I shall split my 25mcgs into four quarters back to the drawing board and 4 times a day. I will put just the four tablets in my little pot then I can keep checking that I have taken them all. Many thanks for getting back to me. Hope you get your sleep. Can I just ask did it frighten you when you had those high heart palpitations? Having been a nurse, I kept calm and just waited for the pulse and heart beats to come down. Took me two days and two restless night sleeps. Good luck. Dianex


It did frighten me a bit but I noticed it was about 3 hours after my last dose so I knew my T3 level was at its highest, more or less, so it would only get better. It frightened me because I wasn't anxious and it shouldn't have been happening. I stayed calm but it was frustrating not being able to sleep or get comfortable, especially as I had work the next day. The racing heart and hot feeling were much better by morning. I just felt very tired.

I also have a little pill box and do the same as you so I know if I have taken each dose :)


Who knows what the precise mechanism is Carolyn. (but that surely holds for most medical treatments ?)

I'm guessing that what you describe is the scenario that docs worry about when the possibility of dosing more than physiologically required amounts of hormone gets mentioned.

It's not a risk free situation (especially in those with e.g. heart issues), which means that there's debate possible (and necessary) as to what is/is not wise in this regard (the answer is likely not going to be a one size fits all deal, will entail some uncertainty, and will depend on how the patient sees it too) - but it's great to see the matter handled in so practical and courageous a manner.

It's a beautiful demo of how patient responsibility and the acknowledgement by our culture and legal systems that medicine is not remotely a complete science surely holds the potential to completely change medical culture and hence the practice of medicine.

Authoritarian bureaucracy by placing the doc on a pedestal that demands that he be all knowing and 100% responsible, and the patient clueless and irresponsible positively encourages blaming the doctor and kicking up a politically correct fuss in the event of anything unforeseen happening.

When with a co-operative approach that shares risk and responsibility it could be so different.

Is it any wonder that in the current way of delivering metabolic medicine so many docs opt for bureaucratically inspired, failsafe and one size fits all treatments that deliver little or no improvement for the patient?



Sorry Caroline but how long have you been on T3 only? I'm nearly four months and I hAd a terrible night sweat myself this week. Only slight and very quick racing heart tho.....


About 3 months, I think. I was on NDT before that but unfortunately that contained too much T4 for me at that time. Maybe you experienced something similar?


Oh I've been more like four months C. I'm doing ct3m as well tho and find that's the one thing that helps me. But yes, night sweat, headache and a little pounding heart last week. I'm up to 80 a day, although I've dropped 10mg since that night sweat....


Ah, you might find it's at least partly your adrenals picking up :)


Yeah could be but if I slip off my strict regime one bit and I'm affected ! Bad nights sleep or too much sugar/carbs and I'm affected. I had a week of 8/10's tho :0) never had that before! Lol always slip back tho. You're never free of ill healths grip! Lol


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