I was told it's not recommended to take T3 with T4 following treatment for thyroid cancer due to the fluctuations in hormone with T3 which means that suppression may not be maintained throughout the day. Is this another NHS red herring to prevent patients from requesting T3 or is it a valid concern? How much does T3 actually fluctuate and would it really affect TSH suppression adversely?
Is TSH suppression adversely affected by T3? - Thyroid UK
Is TSH suppression adversely affected by T3?
Written by
Nanaedake
To view profiles and participate in discussions please or .
Read more about...
36 Replies
•
Nanaedake,
It's nonsense. I've been taking T4+T3 since 2014 and TSH has always remained suppressed <0.01 to my endo's annoyance.
Thank you for your reply Clutter. Very helpful personally for me to know that.
I might have guessed it was Endo nonsense. It would be helpful to be able to refute it knowledgeably. I recall the NHS update on T3 said something to the effect that people on TSH suppression for cancer should not take T3 due to variability so if possible it would be useful to have some research that refuted that assertion - if there is any.
Nanaedake,
I was prescribed T3 only in 2012 for 3 months between thyroidectomy and RAI then switched to Levothyroxine. Prescribed T4+T3 in 2014 by NHS consultant endo who agreed my health was improved after I'd been selfmedicating.
Like Clutter I was prescribed T3-only for the whole of my cancer treatment. For me it was ten months!
I've heard this line somewhere before. It sounds like such convoluted nonsense it would be hard to disprove it specifically.
For one thing the imaginary patient would have to be exactly on the borderline between suppressed and not suppressed, so that they danced over the line during the day. So for one thing you'd have the define exactly what that line was! I feel like we could go on all night with reasons it doesn't make sense!
Good, I want to hear all the reasons it doesn't make sense, the more amunition the better.
I think the clearest argument against it is to take measurements when T3 is in a trough rather than a peak. So after at least the longest time gap you'll ever take the T3 tablets. Then you'll know the TSH is the highest it's ever going to get.
I don't think that the NHS guidelines ever get this detailed about how to dose or how to measure.
shawsAdministrator
Two past posts i.e. In the first, diogenes has responded:-
shawsAdministrator
If lies are told long enough, does it become the truth? It would seem so by the comments made by the Professionals.
NDT has also had similar comments and untrue statements made - despite being used safely for over 100 years. Now no longer prescribed by NHS and members having to source their own. T3 has had the same treatment recently - withdrawn from patients instantly - without warning but insisting that T4 is suitable for everyone. I, for one, know that is definitely not the truth. The 'perfect' excuse was, of course, the cost which was permitted to rise and no overseer protecting the NHS.
Recently Diogenes has mentioned a couple of times that the thyroid itself has an impact on conversion levels in the body, particularly in increasing conversion if the level of T4 production is low, to compensate and keep T3 as high as possible while the thyroid fails. This suggests that if you have no thyroid, then conversion will be poor overall, so a supplement in the form of T3 replacement is helpful.
I don't know if this has been published yet, though. It may be in the brand new paper, as that discusses thyroid cancer patients.
In patient groups there is a lot of talk about people with no thyroid having a special requirement for T3. This directly contradicts the fairly flimsy idea it would impact TSH suppression. But I'm not sure how much its present in respected sources.
I can't get over how flimsy the overall argument is, though. So many thyroid cancer patients are not treated with a suppressed TSH! I do wonder if the same guideline document actually specifies that the TSH should be suppressed when it discusses post-op treatment for cancer patients (if it discusses it at all!).
A lot of thyroid cancer patients have hemi or subtotal thyroidectomy these days and it seems as though the NHS is making up another reason for not prescribing T3 by saying that as a patient still has some thyroid left it's not advisable. However, if TSH is suppressed then the reliance on LT4 is total so it seems the same would apply to someone with partial thyroid as to someone without a thyroid. Both may have low FT3 and need T3 supplement. Doesn't seem to be any definitive answers and NHS seems not to have a clue but are still whipping people's thyroids out without any long term strategy for hypothyroid treatment and symptom control. Moreover, they are not testing FT3 to find out the reasons for symptoms.
Yes, that's true. I mean the larger problem is that the guidance is very brief and simplistic for everything. They don't care what anyone's freeT3 actually is, no matter why they are hypo.
I suppose this particular story comes from the fact they don't care about anything except TSH. So they're extrapolating from that. Someone got into their head that T3 has a short half-life, and therefore they just thought: that doesn't quite fit with our very simplistic model of how we want the TSH to work. And conveniently it's something we were planning to denounce anyway.
The findings are in a paper we've just submitted. The body furiously tries to keep FT3 as normal as possible in the face of a failing thyroid. It does this by boosting body T4-T3 conversion of what T4 is being produced. Ultimately, so much thyroid is lost that the system collapses and enters a radically new state. In both case you might need T4 as a supplement, but if there is active thyroid left, it will do the heavy lifting as regards making T3, so that therapy needn't be as drastic and some control is still present. If there's no thyroid then the body has to do it all, and this is basically a different situation, because there is no thyroid helping out. Indeed this is when some people cannot make enough T3 from T4 alone.
What happens with hemithyroidectomy when TSH is deliberately suppressed for treatment of thyroid cancer? Does the thyroid still produce T3 or is it basically the same situation as someone with no thyroid? Does the body have to do it all in this case?
If there is any working thyroid left it will produce some T4 and T3. If TSH is deliberately suppressed in the presence of working thyroid, all that happens is that enough extra T3 in therapy is used in suppression.
I'm glad it was clear to everyone else, but sorry to say it is not remotely clear to me.
Did you say that if there is any working thyroid tissue left it will still produce T4 and T3 even if TSH is suppressed?
The other way I can read it is that if TSH is being deliberately suppressed it is best to accomplish suppression with enough T3 to make up for the thyroid tissue producing none because of TSH suppression?
Sorry, maybe there is even a third choice if neither of these is right, lol...
No, in hypothyroidism TSH is raised and this partly comes about because the remnant thyroid tissue produces less T4 than when whole, and this + a positive effect of T3 on TSH production forces more T4-T3 conversion by the body from the smaller amount of T4 present.
Okay, but I thought the original question was whether in the case of deliberate TSH suppression, does the remaining thyroid tissue produce T4 & T3? Or is it like having no thyroid tissue and relying on the rest of the body for conversion?
Sorry if you've answered this and I just cannot see it.
Yes it will and adding T3 simply augments what the gland is producing and together suppresses TSH.
Thanks! Does anyone know to what extent T4 & T3 are still produced during TSH suppression?
It will be less than when no T3 was given, but not negligible. TSH suppression is the joint result of enough hormone produced by the gland + the T3 given.
Can you push it to the point where the exogenous administration of T4 or T3 completely eliminates the production of the working thyroid tissue?
Thank you for taking the time to reply 
I've been curious what the mechanism is for the thyroid to boost the body T4-T3 conversion? Or is it not yet known?
Good question. How is conversion process upregulated?
We are getting a bit complicated here. There exists in the body a positive mechanism among several others whereby T3 actually can stimulate TSH production in appropriate circumstances. A failing thyroid is one where the body is stimulated to produce as much T3 as it can to in turn stimulate the the thyroid to put out as much T4 as it can through a T3 positive effect on TSH. So the TSH is raised to stimulate the production of T3 from T4 in the failing gland. Normally this mechanism in health is merely a secondary control to ensure the balance between thyroid output and conversion is finely balanced.
Thank you Diogenes! So it's not as simple as the thyroid producing a chemical to signal the body tissues, as I had hoped 
WOW ! This was a GREAT discussion . THANK YOU !!!
Hi Nanaedake,
I was born with only a partial non working gland and my TSH level has always been suppressed (waiting on latest results) but my last level was 0.54, the one before 0.09. I take 200 mcg of T4 and 20 mcg of T3. I think the increase in the level was before I was on too much T4 - 250 mcg so it was suppressed even more.
Regarding the T3 (hopefully it will continue, but waiting on a phone call to say that I am not getting it anymore) My T3 level last time was 3.5 I feel good on the combination I have now.
I think all the lies about T3 are simply that. The more the Endo's/GP's tell them, doesn't make it true, just convinces themselves. T3 is good for all of us, if used at the correct dose, I am living proof of that and have been on the combination for over 12 years or more. But because they do not understand, they hand them out like sweeties, one pill to fit all and we are all different.
The simple fact, I may not have needed T3, if they had not messed me around in the first place. I was always on 200 mcg on T4 up until I was 32, never had any problems with weight, fertility etc - got tired but no more than anyone else. Then they dropped it to 75mcg literally and my life changed for ever. I now also have anaemia, B12 deficiency and vitamin D deficiency. The anaemia and B12 deficiency do run in the family which I found out later in life, but do walk hand in hand with thyroid conditions. So now despite all the crap I had about how bad too much T4 and T3 were for my heart, I have proved them wrong. Back on my original dose of T4 but added T3.
Always ask for your ranges too when you get the results as most professionals or receptionists are only reading from a script.
At the end of the day, we can live without our thyroids BUT we can not live without the hormones as simple as.
I get so angry at the so called professionals. Remember their theories are simply an opinion and we are justified in questioning that when it comes to our own bodies.
Take care and keep us posted.
Wow, your story is almost identical to a close friend of mine! Born with a partial thyroid, did fine on T4-only all his life. Then in his early 30s a doctor just reduced it. I think the figures may even be the same as yours, was on 200mcg, altho I think his drop was just 25 or 50mcg.
He was very ill for 4 or 5 years, carried on working, got diagnosed with depression and an operation for a sleep apneoa related condition. Has just started self medicating with a little T3.
So sorry for these miserably unhappy experiences caused by lack of knowledge of thyroid hormone by professionals. It can take years to recover from hormone mishandling. I know only too well.
Thank you too for everyone's comments on this thread. The fog is slowly lifting.
Yes it does seem similar SilverAvocado to your friend.
Ironically I kept saying to my GP at the time, "are you sure about the dose, I could understand 25 mcg drop but not 125! She kept saying yes, "She knew what she was doing" ha ha!
The sleep apnoea was diagnosed 3.5 years ago and they think I had always had it but gone undetected all my life.
The T3 was prescribed by a Endo in the private sector only after I was referred by my gyne.
I am now 56 and had 24 years off up and down. Just found out literally this morning that my latest results are back and my TSH is shot from 0.54 to 4.87! So waiting on a call from my GP - seems I might need an increase of T4. Just hoping they leave the T3 alone as they did not check my T3 hormones. Watch this space!
Yes you are all absolutely right in my opinion.
I am possibly the longest living survivor of thyroid cancer, over 50 years.
The use of T3 was commonplace during my many treatments that went on for over 30 years, it was an effective treatment which allowed me to grow up, have a family and live a normal life. I'm female by the way.
To withdraw it from patients is totally irresponsible. We all deserve to feel healthy.
You all need to keep fighting and highlighting this issue.
As far as I knowi t's rubbish and many cancer patients are given T3. I think the endo is making things up.
T3 only is the usual treatment after a total thyroidectomy (TT) . One is given T3 (e.g. Cytomel) for at least three months after the TT and then you get put on Levo - and then problems start for many, but not everyone.
Regarding the fluctuations of T3: externally taken T3 does not fluctuate it decays exponentially reaching half of it potency after about 8 hours (it's half life). You can probably tell when it has hit its half life because you will begin to feel tired. If a doc or endocrinologist is "worried" about a T3 fluctuation they should take hourly blood tests and measure it. This will give a base line for that patient, a very useful piece of info. If, for example, the patient runs out of gas by 2:00pm but has to stay at work 'till 5:00pm it would be a good idea to look at the baseline graph and give a small boost dose of T3 at a critical time coordinated with the graph.
I personally get about 8 or 9 good hours out of my NDT (has T3), I then get about 5 hours of slightly low energy - then pretty much fall asleep about 9:00pm. If I have to go out in the evening I take my pill as late as possible that morning.
Not what you're looking for?
You may also like...
TSH Suppression Benefits and Adverse Effects
http://jeffreydachmd.com/2015/05/tsh-suppression-benefits-and-adverse-effects/
TSH Suppression Benefits and Adverse Effects
hypothyroid patients taking natural dessicated thyroid (Nature-throid- RLC labs) a suppressed TSH...
T3 and suppressed TSH
3 x 5mcg per day. The problem is that my TSH is suppressed at 0.1 which is putting pressure on my...
Suppressed tsh when on T3
direction of literature that states your tsh will always be suppressed when taking Liothyronine and...
Suppressed TSH, on T3 trial
GP/consultant. I was lucky enough to get agreement for an NHS T3 trial, which i started in...
T3 only - is suppressed TSH dangerous?
Very suppressed tsh, on T3 10, years 
Does T3 always suppress TSH?
Suppressed TSH, low T3 and normal T4
Known Graves, suppressed TSH, normal T3/4
