Very revealing!

[greygoose]

This article talks about why some of us Hashi's can't convert and what we can do about it. A bit technical but explains a lot.

hashimotoshealing.com/5-key...

[jimh111]

This article makes some valid points but contains quite a lot of errors. Deiodinase is a very complex subject and is poorly understood, even by experts in the field. Much more research is needed. For example, until a just few years ago D1 was thought to be the major source of T4 to T3 conversion in humans, the current view is D2 produces most of our T3.

Some points:-

D1 produces one rT3 molecule for each T3 molecule. Reverse T3 (rT3) binds to thyroid hormone receptors but is inactive. So rT3 has a blocking effect. I don't think anyone can quantify the relative effects of rT3 v fT3. Consequently, I can't see the point of spending money on a costly rT3 assay.

D1 is up-regulated by high levels of fT4, so it seems to protect against hyperthyroidism. By converting T4 to the smaller rT3 and T3 molecules it enhances reabsorption of iodine. D1 also reduces T3 levels by leaving less T4 available for D2.

D2 is our main source of T4 to T3 conversion, it occurs throughout the body within the cells (not all cell types) much of this T3 finds its way back into the blood. D2 is up-regulated by TSH. When T4 falls, TSH rises and D2 produces more T3, compensating for the loss of T4. Of course this effect is limited, there has to be a decent amount of T4 left to convert.

TSH is stimulated by TRH, if TRH falls then TSH and D2 will tend to fall also. This is sometimes called 'low T3 syndrome'. Stress and particularly depression can reduce TRH levels, also serious illness has the same effect.

Additionally, if TRH is low the pituitary produces TSH with reduced bioactivity. Not all TSH are equal. TSH is not a single hormone but a group of iso-hormones with varying bioactivity. The TSH immunoassay records the immuno-response from these TSH hormones, it does not accurately reflect their bioactivity. TSH assays measure presence, not activity. "A discotheque and a graveyard may have equal levels of presence but different degrees of activity" - Dr Gordon R B Skinner.

The pituitary relies upon D2 activity. Pituitary D2 activity is not regulated like it is in other cells. This makes sense, the pituitary needs an accurate measure of serum thyroid hormone levels.

D3 converts T4 to rT3 and T3 to T2. It is thought to be up-regulated by fT3 levels. D3 thus stops T3 levels getting too high.

Jim.

[gabkad in reply to jimh111]

He has a list of references at the end but no footnotes to the most 'salient' of his points. Not professional writing as far as I'm concerned. He does not support his major claims directly with any research papers or publications.

[greygoose in reply to jimh111]

Well, it was only a rough explanation for us non-technical pleeps. It didn't claim to explain it all in detail. I thought it might be interesting for those of us that know nothing about these things.

[jimh111 in reply to greygoose]

It is an interesting article. Looking at it a bit more I can see it is based on quite old studies. Research conclusions in this area have changed a lot in recent years, so it's important to consider recent studies. (Let's hope it doesn't turn around again in the near future!).

The essential points are still valid:-

1. Thyroid hormone action is very complicated, it cannot be explained by a simple blood test. Signs and symptoms are more important than blood tests.

2. The TSH does not accurately reflect tissue levels of thyroid hormone in all cases. (In mild thyroid failure a high TSH helps the patient by increasing T4 to T3 conversion). There is no link between TSH and hypothyroid symptoms. No study has ever found a correlation.

[greygoose in reply to jimh111]

Well, I think most of us know all that about the TSH, anyway, from experience!

It may be based on old studies, but that's hardly the point, is it. It talks about the détails of why one can't convert, things that people like me know nothing about. It interested me so I thought it might interest others. When newer research is available it will be just as interesting, I'm sure, and if I come across it, I'll post it.

I realise things like this must be very low tech for people like you, but then I didn't post it for people like you. I posted it for the ignorant masses!

[jimh111 in reply to greygoose]

No. This is very high tech stuff. Most endocrinologists will not be aware of it which is one reason why they are so dogmatic. It's useful to post it so that people are aware of the complexities of thyroid hormone. I was just concerned that some of it is inaccurate and people would read it and take it all as fact. It is very useful to know about this sort of thyroid action, even if nobody really understands how it works.

[greygoose in reply to jimh111]

Most endos are not aware of very much at all to do with the thyroid!

Thing is, most people - myself included - will forget the détails of an article like this in a very short time. Unless they are particularly interested in this sort of thing, in which case they will probably research it for themselves.

What most people will take away from it is what is said at the end about how stress and other things can affect conversion, so avoid stress etc. If you didn't know that already! lol

[silverfox7]

Interesting but I suspect a little out of date. My late husband did thyroid research-how I wish I had listened-and one of the people he worked with has a few papers listed which possibly back up the article in some respects. Many contributors are around the same time so I would say that if the article is based around the points made then then it is relevant at that time. Research though moves very slowly so difficult for the lay person to know whether things have moved on or whether the hypotheses still stands. I do know though that research reaches out across the world, my husband worked not only with people in diffent research establishments in the UK but in the States, South Africa and the Netherlands. I would trust a science based endocrinologist over a medic anytime as they understand far more of how it all works but as regards the article I also would like the papers linked to the salient points.

[greygoose in reply to silverfox7]

Perhaps you can find us a more up-to-date paper then. I'm sure people would be interested.

[overnighthearingloss]

Something I was reading/listening to recently suggested that selenium was needed as part of the conversion process. I didnt keep the link but it may be worthwhile to search for info.

[greygoose in reply to overnighthearingloss]

Oh yes, it most definately is.

[eeng]

It's such a shame that under the heading "D3 and D1 Don’t Play Well Together" there is a typo where he says that the job of D1 is to convert T4 to T3, when earlier in the article he explains that the job of D1 is to convert T3 to T4. Also clearly this guy has a business selling various obscure vitamin supplements, probably at very high prices. Apart from that it's an interesting article.

[greygoose in reply to eeng]

Bad editing. Things are going from bad to worse as far as language is concerned. In newspapers there are often bad mistakes like that. Anyone can make them - I do myself - but if you read through what you've written afterwards - or better still, get someone else to do it - they get picked up.

[Hidden]

Thanks

[greygoose in reply to Hidden]

You're welcome.

[Hidden]

Greygoose - thanks so much for sharing. I found the articles very interesting & they have certainly given me food for thought.

I also appreciate the input by others too. They have helped me to realise that i need to read the latest research on this subject.

Many thanks,

Lucy

[greygoose in reply to Hidden]