Evidence that T3 may be required by some people

[helvella]

This is an EXACT copy of a post I made over fourteen years ago (except minor reformatting):

It is often suggested and argued that T3 replacement is required by at least some hypothyroid people - and that T4 alone does not work for them. Now there is some evidence that this is absolutely the case, and it even identifies a genetic polymorphism that is associated with this.

Although published in May, it seems only now to have made it into PubMed. Unfortunately, so far only the abstract appears to be available.

F1000 Med Rep. 2010 May 11;2. pii: 34.

New insights into thyroid hormone replacement therapy.

Acosta BM, Bianco AC.

Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine 1450 NW 10 Avenue #3054, Miami, FL 33136 USA.

Abstract

It is widely accepted that thyroid hormone replacement for patients with hypothyroidism can be fully accomplished with levothyroxine monotherapy, as assessed by serum thyroid function tests. However, approximately 10% of hypothyroid patients are dissatisfied with the outcome of levothyroxine monotherapy, and physicians continue to report benefits from combined levothyroxine-triidothyronine therapy for some hypothyroid patients. Recently, a large prospective study reported that the benefit of the combined levothyroxine-triidothyronine therapy is associated with the Thr92Ala polymorphism in the type 2 deiodinase gene, which is present in about 15% of the general population. If confirmed, these findings indicate that personalized medicine is rapidly catching up with modern thyroidology.

ncbi.nlm.nih.gov/pubmed/209...

Here we are in 2025, and STILL seeing so many refused the chance of T3, having T3 removed or reduced, etc. And a certain Bianco AC still plugging away...

Adding link to original post:

healthunlocked.com/thyroidu...

[arTistapple]

14 years? Well that still gives medics at least another 16 years before it hits mainstream medicine. If ever, as long as we have our present dimwits in charge.

[BB001]

I'm glad that the link between Dio2 deiodinase and need for T3 is getting exposure. There is though more to it than this. I'm normal for Dio2, but homozygous for Dio1 and my conversion rate of T4 to T3 is very poor at 0.16.

[helvella in reply to BB001]

I think there has been progress in understanding the genetics in the past fourteen years.

[Tina_Maria in reply to helvella]

Perhaps on an abstract scientific level, but I think (with a few exceptions) the thyroid medical community is still lagging behind.....😅

[FallingInReverse in reply to BB001]

Are you saying it doesn’t matter if you have the Dio mutation. Rather, bad conversion is bad conversion and approach is the same in regardless of gene status?

I’m wondering whether getting the gene test is worth it - or if seeing conversion is enough to make dosing decisions.

Thoughts?

[helvella in reply to FallingInReverse]

The view of these variants seems to have gone from "that explains it" to "if it has any impact, it is very minor". And some official sources advise not to take any notice of genetic tests.

And more is known of the details of variants which exist.

I suspect that the story of genetic background in thyroid issues is going to prove far more complex than a variation or two. But those particular variations might be very significant in some people yet less so in others.

[BB001 in reply to FallingInReverse]

I'm saying that Dio2 isn't the whole answer. People with normal Dio2 but with Dio1 also have issues with conversion of T4 to T3. Given that my conversion ability is so poor I suspect there are other as yet unidentified causes of poor conversion. In my case being able to prove I had the Dio1 mutation helped me argue the case for me being prescribed T3 medication. Though I also gave my endo test history for many years in a table with columns for date, tsh, ft4, ft3, conversion rate (ft4 ÷ft3); plus extensive written history that included my TSH at initial diagnosis, the blood test result when I came off all thyroid medication for a week before switching to bovine NDT, the effects and improvement in symptoms of switching to bovine NDT, etc.

[FallingInReverse in reply to BB001]

Thanks! Nuanced and helpful answer : )

[Noelnoel in reply to BB001]

What was the thinking behind stopping thyroid medication for a week before starting NDT?

[BB001 in reply to Noelnoel]

I wanted to know how much thyroid hormone my own thyroid was producing. The answer was none, so I didn't last longer than a week. It did though give me a good basis to introduce NDT from as I knew that any symptom changes were due to NDT. As I also had a blood test immediately prior to starting NDT to act as a baseline, I had documented proof that i was definitely hypo, which satisfies one of the guidelines ( I can't remember whether it is NICE or NHS) for being prescribed T3.

[BB001 in reply to FallingInReverse]

Be careful some of the testing companies only test Dio2. In my case I found Dio1 important as well.

[andyjs2 in reply to FallingInReverse]

I think if you are taking T4 and your FT4 is good/midrange but your FT3 is still low in range or lower that’s probably enough to convince me that T3 is required, no matter what the cause for your poor conversion is.

[FallingInReverse in reply to andyjs2]

My issue is I was out on too much t3 too early and all at once … I was dropped from 50 Levo to 25 Levo + 10 t3 daily.

A year or so later I’ve been titrating t4 and keeping the 10 t3 steady. But now I’ve arrived at an over range ft3 and am going to start reducing t3.

So I have the idea to get my dio genes tested… I’ve always been curious how I convert but can’t tell since I’m already on t3!

[BB001 in reply to FallingInReverse]

or if seeing conversion is enough to make dosing decisions.

Conversion ability can be affected by other things such as low vitamin levels, poor gut health, and illness. So these need to be addressed as far as possible first. But even when I ate only foods that i wasn't reacting to and thereby had good gut health, got my vitamin D, B12, folate, iron, ferritin, magnesium etc levels to be good my conversion ability only increased from 0.16 to 0.20, which is still classed as very poor. So yes, from a dosing point of view, knowing you have poor conversion is sufficient to know you need some T3 in your medication. However, being able to demonstrate that my other vitamin and mineral levels are good, helped rule out these as a reason why I had residual symptoms, and helped strengthen my argument for needing T3.

Edited: for typos.

[thyroid-warrior]

This is encouraging. I was thinking of doing genetics testing but haven’t got around to doing it yet. I know it’s slow progress but I still remember over 30 years ago when I was first diagnosed with hypothyroidism as a child and the doctor said as long as I was taking medication, I should be able to lead a normal life. 😂 As such I never reported any symptoms even though I had brain fog and fatigue. I’m glad that I’m still around for this progress.

[FallingInReverse in reply to thyroid-warrior]

How unfair for a child to be told “normal” and for you to equate brain fog and fatigue with “normal.”

When did you start figuring out differently and advocating for yourself?

[thyroid-warrior in reply to FallingInReverse]

Four months ago. I felt more and more fatigue and could hardly work and the TSH/FT4 blood results returned normal. Doctor said it definitely wasn’t the thyroid and tested other potential problems, all of which returned normal. Meanwhile fatigue got worse. It took me an entire month to figure out maybe I should increase my dosage by myself without a doctor’s recommendation. I was seeing an acupuncturist who used to be a medical doctor, said my pulse was very low and could likely be under-medicated.

[BB001 in reply to thyroid-warrior]

This mirrors my experience.

[healthkiwi]

To be fair to Bianco, 20 years ago he was very much on the "no need for T3" side of the argument. The thing that has impressed me is that over the years he can be seen to be a truly great scientist. He looked at the accumulating evidence and CHANGED HIS MIND! And says he was wrong! ( how often do you hear that?) and that one of his failings in the past was not to really hear what patients were saying. I really appreciate the intellectual honesty, the human openness, and the mea culpa. The dinosaurs clinging to their "no T3" stance are looking stupid. Ruining their own reputations.

I know it doesn't change things today for so many of us, but as T3 becomes less exorbitantly priced, and as more of us bolshy patients speak up, and as the evidence stacks up, the guidelines will change.

[tcpace in reply to healthkiwi]

I must admit I have tended to dismiss Bianco because, some time ago, he seemed to be saying that there was little if any benefit to be gained from T4/T3 therapy, based on using very small T3 doses in his research trials. Maybe I need to look at his current thinking. As someone with a scientific background, I'm always impressed by any scientist who changes their mind as more evidence emerges.

[SarahJane1471 in reply to tcpace]

Try his book from last year. I was impressed by it and wrote my “review” of it on this forum ( can’t remember how to post a link 🤦‍♀️). He does think that even with T4/T3 therapy the TSH has to be in range. And not all members were as impressed as I was by the book. 🤷‍♀️

[helvella in reply to SarahJane1471]

Here I go 🤓

healthunlocked.com/thyroidu...

[tcpace in reply to SarahJane1471]

Thanks but if Bianco thinks a sufferer can take a T3 dose sufficiently low that the TSH remains in range then he's barking up the wrong tree. I note from the link provided below by helvella that the late diogenes was not at all impressed.

[SarahJane1471 in reply to tcpace]

Yes that is the downside. But I’m an optimist and I’m hoping if Bianco can change his mind after many decades then others can.

[Sparklingsunshine in reply to tcpace]

We have a ember on the forum, McPammy who is on combi therapy who manages to keep her TSH in range but she is about the only one who does. My TSH was very low on just Levo alone.

[nightingale-56 in reply to Sparklingsunshine]

My TSH stays in range on NDT too, for which I am grateful. Saves arguments with Doctors.

[FallingInReverse in reply to tcpace]

tcpace SarahJane1471

I just read something yesterday about “micro-dosing” t3… if ones t4 is mid range (like 50-60%) but t3 is really low… that you can take, say, 2.5 t3 daily and this will keep your tsh not suppressed.

Is this what Bianco talks about?

[healthkiwi]

In the Thyroid Trust interview last month (on YouTube) Prof Bianco seemed - to me at least - to be less fixed on the TSH. He acknowledged that some patients on any combined LT4/LT3 may only feel well when their TSH is " suppressed". He said the proper way for a physician to deal with this situation is TO LISTEN TO THE PATIENT. The doctor's job is to explain to the patient that there are perceived risks, IF the patient is actually overmedicated. If the patient says their Quality of Life is most important, that's a reasonable position to take. The key here is that the physician should then ensure this patient is frequently monitored and ALWAYS test T4 and T3 along with the TSH. It sounded as if he has a real concern about Drs who review without getting T4 and T3 results. He said more than once the TSH is very helpful for initial diagnosis, but should never be used on its own for ongoing treatment decisions.

[tattybogle in reply to healthkiwi]

i have the impression that he's more on board than he can openly admit with the idea that low/ even supressed TSH might be necessary/ ok for some on T3

i think he's going with a plan of ... "how do you eat an elephant ? ~ one bite at a time"

~ First get the 'TSH dinosoar club' to accept T3 use as advantageous /safe for those patients who can keep TSH in range/ or measurable while getting clear benefits from T3.

~Then once it's more commonly prescribed and the dinosoars are more comfortable with it , then try to deal with the institutionalised resistance to low TSH.

[TaraJR in reply to tattybogle]

Oh I fervently hope so. I think you could be right on this.

[healthkiwi]

He's very particular about not going further in public than the current evidence will substantiate. So many times he says "we do not yet have good evidence, or the answer on that question". But he's a highly competent researcher, scientist, physician AND administrator, chaired many panels and run bodies of fellow professionals 👿🤡🤖 . So, yes, I agree, he's aware of the size of these elephants - or dinosaurs. This is a long process. He may regard this as the culmination of his very fruitful life's work. I have 2 images: turning the ocean liner - or herding cats 😸😾

[tattybogle in reply to healthkiwi]

🐈🐈🐈🐈🐈🚢