Reverse T3 and T3 - not clear about them?

[tilly83]

Can some wonderful knowledgeable person out there tell me the difference in easy to understand language.... so when I see my endo I don't feel like the idiot at the back of the class? Thank you!

[Clutter]

Tilly, T4 converts to T3 and rT3. T3 is the active hormone and rT3 is inactive. rT3 levels fluctuate throughout the day and it is a mechanism to prevent conversion of excess T3 causing hyperthyroidism. rT3 rises as T3 falls and vice versa.

GirlScout2 posted this interesting article tiredthyroid.com/rt3.html

[tilly83 in reply to Clutter]

Thanks so much Clutter, still hard to get brain around but will look at link... I've been having T3 measured when I've had tests but not reverse T3 is this important to ask for? x

[Clutter in reply to tilly83]

Tilly, when I asked for rT3 endo told me it isn't tested on the NHS.

The link I provided suggests that drilling down to find the causes of low/high rT3 which are different issues may be more important than simply having them. The author disagrees with other bloggers views that T3 receptors are blocked by high levels of rT3 and can only be 'cleared' with high doses of T3 only.

I usually need to read detailed articles and research papers 3/4 times over a period to be able to make sense of them.

[tilly83 in reply to Clutter]

sorry Clutter... been in outer Hebrides..... thank you for reply x

[Heloise in reply to tilly83]

stopthethyroidmadness.com/r...

This website thinks reverse is an important number if it is compared to free T3.

High or low cortisol or low iron may be the cause of reverse T3....whether it blocks receptors or hinders the total conversion of t4 I don't know.

[tilly83 in reply to Clutter]

comprehensive link, rather feel I need to have science degree to grapple with concepts....!

[Schenks in reply to Clutter]

Hi, Clutter - thanks for re-posting this link: I'd never have seen it and it's fascinating. I'm trying to find out who is behind the site and blog - it seems whoever s/he is, s/he is intent on not being found. Do admin peeps know any more about this person? (Sorry to muscle in on your question, tilly, but I'm on a similar quest to you!)

[Clutter in reply to Schenks]

Schenks, Barbara S. Lougheed tiredthyroid.com/blog/about... author of

amazon.co.uk/Tired-Thyroid-...

[Schenks in reply to Clutter]

Thanks, Clutter - just bought it!

[helvella]

Levothyroxine (T4) contains four atoms of iodine in each molecule of T4.

When we convert the T4 into T3 one of those atoms of iodine is split off from the T4. But not all the atoms of iodine are in the same place - if you take one atom of iodine off the T4 you end up with T3; if you take a different atom of iodine off the T4 you end up with Reverse T3.

There is an OK diagram on the Wiki article:

en.wikipedia.org/wiki/Rever...

Both T3 and rT3 can lose another iodine atom to become T2.

Rod

[tilly83 in reply to helvella]

Thank you Rod, can feel what's left of brain crumpling......don't think will be opening mouth on that with endos as all too slippery for me.... !

[shaws]

Tilly, if someone gives your the answer you will know more than the Endocrinologist, I bet.

If you go to the date March 24, 1999 on this link for an explanation:-

web.archive.org/web/2010103...

[tilly83 in reply to shaws]

Thanks Shaws and apologies have been in wilds of Hebrides,,.... appreciate your help x

[jimh111]

reverse T3 is produced from T4 by a process called 'deiodinase'. rT3 is inactive and so when it binds to a receptor it blocks the receptor so T3 cannot bind. There are 3 types of deiodinase abbreviated as D1, D2, D3.

D1 produces equal amounts of rT3 and T3 from T4. D1 is up-regulated by increasing levels of T4. D1's main purpose is thought to be recycling of iodine. It is also thought to reduce hyperthyroidism by the fact it produces equal amounts of T3 and rT3 and leaves less T4 available to D2.

D2 converts T4 to T3 within the cells. Much of this T3 finds its way back into the bloodstream. D2 is thought to be up-regulated by TSH (and possibly down-regulated by T3, if I remember correctly).

D3 is up-regulated by T3. It converts T4 to rT3 and T3 to T2. So D3 basically reduces T3 and so prevents hyperthyroidism.

The 3 deiodinases work together to regulate cellular thyroid hormone activity. This is a very, very complicated subject and is not yet fully understood.

This is my current hobbyhorse:- Even if you get a rT3 assay done I don't think anyone really knows how to interpret the results, certainly not in a quantitative manner. There are a number of conditions that lead to elevated rT3 levels (e.g. depression, starvation, heart attack), but essentially if you have one of these you will know about it anyway. So personally I wouldn't bother askiing for a rT3 assay, it is expensive and doesn't really help with diagnosis or treatment. You might get a different result the next day. I'd devote my energy to explaining what symptoms I have and hope the endocrinologist takes these into account.

Jim.

[Girlscout2 in reply to jimh111]

Jim

Hurrah! A man after my own heart. Have you read this, her book has a much longer chapter explaining all this which I read for the third time last night. tiredthyroid.com/rt3.html

Also

tiredthyroid.com/blog/2013/...

I agree that RT3 occurs naturally and that it's a symptom not a cause and also that T3 affects the speed at which T4 converts to RT3. Indeed NDT contains RT3 (pigs make it) so the more NDT you take, the more RT3 you have also ...

In the article above she explains that RT3 does not block the receptor, in fact the issue is that neither T3 or RT3 can get in the cell.

It makes my head hurt but I think my instincts that all this ratio and clearing stuff is a red herring are correct. Seems you think similarly.

Rebecca

x

[jimh111 in reply to Girlscout2]

I haven't read the tiredthyroid link. I'm a bit unsure about the tiny bit I've skimmed so far, I prefer to work from research papers rather than interpreted information. The real point about rT3 is that so little is understood about it at the moment. What we do know is that it is produced by type-1 and type-3 deiodinase and both are up-regulated in states of high thyroid hormone. So it seems reasonable to assume rT3 has a role in reducing thyroid hormone activity.

rT3 does bind to thyroid hormone receptors with no effect. So in this sense it is occupying a receptor and blocking it. I believe rT3 has a very short half-life so I don't know where the '12 weeks to clear' stuff comes from. Clearly if a patient has a disorder that produces extra rT3 then taking a T3 containing medicine will overcome it to some extent.

[Girlscout2 in reply to jimh111]

I hear you, I'd recommend reading it even if you then move on, she has over 70 references for that part I think.

Thanks for your reply. I agree re 12 weeks also!

Rebecca

[sulamaye in reply to jimh111]

Putting all the various points of view to one side jimh111 do you think that solely using t3 for a limited period of time would reduce rt3 and if so what period of time aproximately?

[Clutter in reply to jimh111]

Jim, It took 10 weeks off T4 and a week off T3 before the symptoms I ascribed to T4 over replacement cleared. I honestly don't know whether this was rT3 as it wasn't measured, long term over replacement fixed by detoxing or just an inability to tolerate T4 only. Symptoms resumed within days when I reintroduced T4 but calmed when I added T3.

[jimh111 in reply to Clutter]

I haven't studied rT3 in detail but it's quite possible that it took quite some time for the T4 to clear out and as long as you have high T4 it will convert to rT3. So it's a bit pedantic but perhaps it's the T4 that is taking a long time to clear out rather than the rT3. Also if your TSH is suppressed for some time it will take quite a while for it to recover, if at all.

[Clutter in reply to jimh111]

Jim, Yes that makes sense

[sulamaye in reply to Clutter]

Clutter what specifically were the symptoms you ascribed to t4 overload, if you don't mind me asking?

[Clutter in reply to sulamaye]

Sulamaye, palpitations, parasthesia, internal tremors, shortness of breath, fibro symptoms, COPD symptoms, dizziness, fatigue, weightloss, muscle weakness, hair loss etc.

[sulamaye in reply to Clutter]

By internal tremors do you mean a kind of thrumming inside your body, invisible but a bit like a mini motorbike revving in your cells? Paras thesis? Does that relate to tingling?

What is copd?

[sulamaye in reply to sulamaye]

Clutter bar the weight loss it sounds very similar to my experience of m.e. That's why I keep wondering whether I shd go t3 only temporarily. How did you manage the transitions?

[Clutter in reply to sulamaye]

Sulamaye, I added 20mcg T3 to 100mcg T4 with slight improvement which tailed off after a few weeks. I was convinced T4 was the problem so stopped it and switched to 3 x 20mcg T3, the dose I was prescribed after thyroidectomy. I tried various doses of T3 up to 120mcg over a few weeks without improvement and settled back on 60mcg. 8 weeks after stopping T4 I also stopped T3 for 4 weeks and the symptoms which accrued since I started T4 stopped after 2 weeks. I may not have waited long enough for the T4 to clear my system. After 4 weeks off meds I started 100mcg T4 but palpitations and tremors started within 2/3 days so I added 20mcg T3 which seemed to calm down the adverse effects I had on T4 only. I've titrated T4 and T3 several times and endo prescribed 100mcg T4 and 40mcg T3 in May but I dropped T4 to 75mcg when it became hot in June as I felt a little overmedicated in the heat. I feel ok on this dose although my hands and feet are very cold again.

[Clutter in reply to sulamaye]

Internal tremors felt like I was shaking inside. Legs felt trembley and shaky as if they would collapse under me, particularly descending stairs. Parathesia was in hands, numbness, pins & needles, tingling and tremors. Chronic obstructive pulmonary disease (COPD) but 10/12 weeks off Levothyroxine my breathing was good and lung function test results were good and showed no disease.

[sulamaye in reply to Clutter]

Clutter very interesting. So it's not the thyroid gland that converts t3 to t4 it happens in the body? I am beginning to suspect that I've had to much t4 to t3 for too long. You haven't gone down the NDT route? It's so hard to find ones own balance with gps making all the decisions on bloods. I guess bloods are irrelevant after having a thyroid removed so they are more likely to take account of how u feel.

I have tingling mainly in face, arms legs and feet hands. Thrumming can be throughout. I just never realised how many of my m.e symptoms cd be thyroid related. I am praying it's what's at the root if the last three years of hell!

Thanks for all your help, everything everyone says is helping me put the puzzle together.

[Clutter in reply to sulamaye]

Sulamaye, Some T3 is produced in a working thyroid. I've read 20% but that may be over stated. Sadly, little notice was taken of my symptoms hence chest x-rays, ECGs, lung spirometry etc. cos it couldn't possibly be Levothyroxine making me ill

Is your B12 good? Numbness, tingling especially in feet and hands can be signs of B12 deficiency.

[sulamaye in reply to Clutter]

On that recent test no my B12 was near the end of the range, but I had tingling etc even when injecting b12 and level was 1100 range. I'm not sure if it's so low now in response to the stress to my body of having such a radical drop in meds as I know stress eats up b12. I hadn't had it as a symptom for about a year and even then no where near as it's been since my meds were cropped.

I am beginning to wonder if over medicated and that triggered by major operation no. 3 lead to me hitting the wall. That's why I keep toying with the idea of RT3 and whether i should try to clear it or whether if I get my ratio spot in it will gradually clear itself anyway. My problem with the cut out all t4 to starve rt3 approach is that unless thyroid gone or producing nada one will still be making some t4 that the body surely would still be turning to rt3 if on a high t3 dose alone? Also perhaps better overall to find right ratio and let body get it's balance back more clearly. Surely if t3 is minimal in dosage rt3 will be processed out of body to get a better balance of its own accord?

This is how my brain is working at the moment. I can't believe they still don't listen to you, no I can believe it actually, doctors seem to have such a lack of enquiry and wondering in their approach, they think they are so scientific but really they don't know what science is, they just think it's the application of what is known to justify a familiar treatment approach, lucky Estein didn't take that approach!

[mstp]

I'm using the answers to your question as a benchmark to how well I am. For the last four years my brain cuts out whenever I try to get to grips with the answer. I figure that one day I will look, read and inwardly digest. That will be the day I know I'm finally ok. x

[tilly83]

Thank you and sorry for late reply I have been in Outer Hebrides. Camping. Soaked, cold but very very beautiful place....x Oh and as for my brain there was one road on Harris island so only had to go left or right but still got lost!