John Dommisse interview by Mary Shomon with contrasting idea about T3 only.

[Heloise]

thyroid-info.com/articles/d...

Secondly, treating with T3-only is almost as bad as treating with T4-only in most cases and worse than T4-only in some cases. I say 'almost as bad' because, since 90% of thyroid function is carried out by T3, correcting the T3 level is a good thing. However, the brain needs T4 to be present in the blood in a good amount because T3 doesn't cross the 'blood-brain barrier' and get into the brain directly. T4 has to get into the brain first and then convert to T3 in the brain tissues. So the cognitive effects of a low T4 level would continue because T3-only treatment raises the T3 level a lot, often way above normal (with all the dangers inherent in that situation), and, by lowering the TSH level, this also lowers the T4 level to way-below normal. I cannot understand why anyone would want to treat with T3-only and not use both thyroid hormones, as needed to optimize BOTH free-levels. This is not to deny that many people treated with T3-only will improve in many ways; after all, T3 is a very important hormone; but they would improve much better and with less ill-effects if both their FT4 and FT3 levels are optimized and neither one is overtreated or undertreated.

MS: What are your thoughts about the need for T3 in addition to T4 as a treatment for hypothyroidism?

JD: In my opinion, it is essential in most cases, in order to obtain the optimal response to treatment. There is a minority of hypothyroid cases that is able to convert T4 sufficiently to T3 in the peripheral tissues to produce an optimal free-T3 level, as well as an optimal free-T4 level, without prescribing any T3-containing preparation. I don't have any fixed combination of T4 and T3 that I use. The most important thing to do when prescribing any T3-containing preparation is to write it as a twice-daily, after brkfst and supper, prescription. This is because, unlike the T4-hormone, T3 is rather short-acting, with a half-life of 8-12 hours (meaning that half of it is already metabolized away in that time).

[Moggie]

Great article. A lady I know is on T3 only and has been for years but she keeps saying she is sure so would do better with some T4 in her body as she feels it needs it but everytime she tried to re-introduce it she suffers with side effects. I could never quite understand her way of thinking but she is a person who is VERY in tune with her body and it looks like she could be right.

Thanks for sharing.

Moggie x

[deskplant in reply to Moggie]

This is exactly the same as me Moggie. I could have written your comment here:

"A lady I know is on T3 only and has been for years but she keeps saying she is sure so would do better with some T4 in her body as she feels it needs it but everytime she tried to re-introduce it she suffers with side effects."

However by looking on this forum I came across a post which references liquid T4 which people can do better with over the pill version. And i want to try that.

I must say categorically that T3 can massively improve brain function. The statement that it does not help is complete nonsense. I note Rod has referenced MCT8 as a carrier route to the brain. I did not find ANY cognitive benefit from syn T4 only more illness.

Secondly the note that T3 is short-lived is also nonsense. It may very well depend on the dosage. But I was on 150mcg of T3 only and the effects rippled on for 3-4 weeks. The reason I stopped taking it was because I ran out of money to buy it as I was self treating. But that duration may easily be because of the dosage level and lower doses may lose impact sooner. In contrast I could feel the T4 out of my system in 24 hours. If I missed one day of T4 I was nearly dying on the floor.

Currently I am doing a 2 week without anything stint for blood tests, longer if I can manage it. And it's 8 days and I can feel the thyroid deficiency kicking in but I was on a lower dose of 100mcg T3 and levo (100mcg which did nothing).

Of note as well is the Circadian rhythm also mentioned in these posts. I am much worse in the morning than the afternoon. With T4 I feel the rise and fall with T3 I'm even throughout the day despite only taking it once (I found once in the morning better than splitting it usually).

[Moggie in reply to deskplant]

She looked into the liquid Eltroxin but at £288 per month for the equivilant of 100mcg's daily found that it was out of her range.

Moggie x

[deskplant in reply to Moggie]

HOW MUCH!!!!!!!!!!!!!!!!!!????????????????? Oh my goodness. Who can pay for such things? Not me either.

[Moggie in reply to deskplant]

This was the one and only reason my GP refused to give it to me. I cant understand a chemical company manufacturing a product and then making it so expensive that the main stream NHS will not give to its patients.

Moggie x

[parafluie in reply to deskplant]

Have you considered taking your daily dose at bedtime? I take mine at bedtime (just as I turn off the light) and it carries me through. Divided doses made me feel worse and nighttime dosing has been best for me. Since you seem to do well with single dose . . . just a thought. It sure makes me sleep well and have a good morning!

[Hidden]

I certainly need good levels of both too.

I find that T4 has sort of got hate campaigns against it by people such as STTM, which is a pity. I suppose it's because it is so often the only thing offered. But it's unfortunate because Levo is a good med for a lot of people, and for even more in combination with T3.

[helvella Administrator]

The article is interesting - but getting long in the tooth. I think it was published in 1999 - but the site always displays today's date. T3 can cross the blood brain barrier via the MCT8 transporter. However, there can be problems with this - for example some research suggests that this will not happen in at least some foetal rat brains. So, as always in the wonderful world of thyroid, nothing is quite as clear as it might once have appeared.

And various oddities about the MCT8 transporter appear to be behind all sorts of developmental issues.

Also, the precise phrasing about T3 being short-acting misleads. Certainly, the blood levels drop quickly. But its effects ripple on for at least days - maybe towards a week?

Rod

[nobodysdriving in reply to helvella]

well said Rod re: T3 being longer acting than what it's advertised for We know Dr Lowe did say this

[helvella Administrator in reply to nobodysdriving]

And here is a picture:

hindawi.com/journals/jtr/20...

From a rat. 100+ hours.

[nobodysdriving in reply to helvella]

Rod, you're so 'cool'

[helvella Administrator in reply to nobodysdriving]

I like my pictures.

This paper appears to possibly identify another T3 blood brain barrier transporter:

ncbi.nlm.nih.gov/pmc/articl...

[nobodysdriving in reply to helvella]

[Heloise in reply to helvella]

I have never heard of this man but the article did say updated January, 2013 so i thought that meant it was still relevant. The comment about T3 was rather disturbing for those who are solely on T3. Hopefully there is some sort of compensation.

[helvella Administrator in reply to Heloise]

It has annoyed me from the very first time I visited the site - the updated date is always today. Just checked - 25 January 2013.

But it is interesting nonetheless.

[Heloise in reply to helvella]

So far this is what I have found on T3 and its half life. It is admitted that there is more to know about this subject.

In addition, because T3 synthetic hormones have a

> four-hour half-life, your peak dosing will occur

> within four hours of taking the medication

> followed by a decline. For this reason, it is not

> uncommon for your doctor to prescribe synthetic T3

> medications as a dose to be taken n the morning

> and then a second dose to be taken four hours

> later. In doing so, your doctor is ensuring your

> T3 levels are stabilized throughout the day and

> then permitted to diminish as bedtime .

The half-life of T4 is 5-7 days; the half-life

> of T3 is only 1 day. Approximately 99% of the

> circulating thyroid hormone is bound to plasma

> protein and is metabolized primarily by the liver.

the short half-life of

> T3, which is only 2.5 days.[3] This compares with

> the half-life of T4, which is about 6.5 days

[helvella Administrator in reply to Heloise]

Some people find that allowing the level of T3 to drop too far results in less good sleep. Taking some at bed-time, although not exactly common, is quite widely reported.

The half-life of T3 as measured by the usual techniques (and, indeed, that of T4) varies. In someone who is HYPO, it is shorter. In someone who is HYPER, it is longer.

The ratio of bound to unbound T3 is typically closer to 300:1. For example:

Free triiodothyronine (FT3) 3.5–7.8 picomol/L

Total triiodothyronine (TT3) 1.2–2.6 nanomol/L

Remember,this is the half-life f the substance in the bloodstream. The effects of that T3 ripple on for at least several days. After all, it goes from bloodstream into lymph thence into cells where it is actually used. That all takes time but would not appear on any current day test.

[Heloise in reply to helvella]

There is much to understand about T3. I found mention of a Low T3 Syndrome so am perusing articles. I did a search here and found no threads but perhaps it is called something other than Low T3 Syndrome.

This article states that it is actually not about the thyroid. Have you heard of this before: chriskresser.com/low-t3-syn...

[helvella Administrator in reply to Heloise]

Yes - and it a weird mystery.

I don't recall it being mentioned but, as you say, it seems to be "something else". I was reading an abstract about it the other day:

ncbi.nlm.nih.gov/pubmed/231...

[snowstorm]

Combination treatment makes absolute sense. However, like the lady mentioned above, what if you highly intolerant to T4? as in my case. Will never be able to take it again. The side effects are, well, no words to describe really , 36 in all, some have actually altered body shape and others have left sore & tender spots in some areas which I find unacceptable. NHS won't/can't do anything about them. Am on T3 ---25mg --- quarter tablet daily. Even with this, I had to come off it for a week as some of those ghastly side effects were rearing their ugly heads again. Despite blood results (TSH too high and T4 needing to be raised a little), am I being treated for the right thing? This is the big question for me.

[Hidden]

I can understand the need for some T4 but I had every side effect listed on the levo leaflet and simply cannot tolerate it.. I do better on Erfa and infact believe that the T1, T2 and calcitonin in it is used as I have no thyroid now. What were they for originally? Not nothing, that's for sure. So, even synthetic T4/T3 didn't suit me for these reasons.

Nothing is ever simple right enough. I looked on the NHS medicines list and had to laugh. There were approx 40 medicines for treating diabetes, about ten for dandruff. Two for hypothyroid and one of those, T3, is seldom prescribed. Something far wrong here.

[parafluie]

What's new about this? Many people do well on NDT, some don't. Many people do well on T4, many don't. Some people do well on T3, many don't. Many people do well on divided doses, some don't. Find what works for you (yeah, it's hard and it changes). Fight for you freedom to be healthy.