Thyroid UK

T3 in NDT compared with synthetic T3

Is there any difference between both T3s in terms of the release of their action?

Is T3 in NDT somewhat more slowly released? (since NDT contains some globulins I guess)

Is that one of the reasons why some people do better on NDT than on synthetics?

I would really appreciate your personal opinion and experience.

Thank you,


15 Replies

Here is an explanation

Its thought that the synthetic t3 is unbound, which is why you have to multidose but the t3 in ndt is bound. I found ndt to be much smoother, with none if the ups and downs.

Synthetic meds cannot be the same as natural meds, because the manufacturers would not be able to get a patent.


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Galathea, thank you.

That is what dawned on me yesterday - that T3 in NDT may be bound, thus being more tolerable for patients.

Actually do you seem to tolerate higher doses of T3 in NDT than synthetic T3?

I cannot get better on T4 only, I don't tolerate T3 ( I have a very low ferritin level, but otherwise perfect iron panel, it may be due to another illness I have.)

I am from Bulgaria and my only choice of NDT is Thailand's Thyroid-S or Thiroyd.

I have chosen the wrong place to get thyroid disease at!


There is a more recent thai medication by tr mann Also in thailand. I am doing well on it, and i can take thiroyd just fine, but not so good with the thyroid S... It needs extra breaking down so doesnt suit everyone.

I was at one point on 50 mcg of t3 but am now settled on 3 grains of ndt which gives about 27 of t3 and 100 mcg of t4. Many would say the uk is also the wrong place to get thyroid disease too.

What are you taking to increase ferritin? Some swear by eating cooked liver ever week.


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I am going to order some Thyroid-S and Thiroyd from Thailand. Although I am a bit concerned about aliminium in Thyroid-S and all the ingredients. On the other hand, I feel so bad, that I don't care so much anymore.

I have also read on this forum that sometimes the shipment from Thailand gets confiscated by customs. So I am trying not to raise my hopes too much.

I cannot tolerate ordinary T3, it gives me a fast heart rate and that's it - doesn't seem to alleviate my hypo symptoms at all. Don't know whether it's the ferritin to blame or the T3.

T4, on the other hand, fixes me for a short period and then throws me into hypothyroidism again. I guess I build up rT3. I can tolerate enormous doses of T4 though.

My ferritin is 15 (4-104). I don't take anything for it since the rest of my iron panel is good. Iron is 21(6-26), tranferrin saturation is 31% I think. Maybe I can benefit from small doses of iron I guess, but not much. Anyway I cannot raise ferritin much since my iron will go over range... :(

Hemoglobin is 145. I really don't know where this low ferritin comes from. I do have another autoimmune disease (with great inflammation) though which may be lowering it, or the Hashimoto's itself.

I didn't quite understand what you mean by "Thyroid-S needs extra breaking down".


Thyroid-S is said to contain a slow release substance (I think it's called Eudragit) which slows down absorption by the also contains cellulose (like Armour), which is also said to bind thyroid hormone. I know some on Thyroid-S chew the pills up and that seems to make it work better, by making the hormones within more accessible to the body somehow.

If you are in Bulgaria, you can order all three brands of NDT (Thyroid-S, Thiroyd, TR TMan). I have used a reliable supplier in the EU in recent years and will go back to ordering from X if Erfa does not work out for some reason. It's more expensive buying NDT this way compared to ordering it directly from Thailand, but delivery would be guaranteed because of free movement of goods in the EU. Please let me know if you want to PM you the details.

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Oh, yes, Anna, please PM me!

BTW I feel kind of the same on T3 - over and under-medicated at the same time.


I seem to remember that Eudragit is a make and they produce a numb er of substances some of which are coatings rather than slow release agents.

Did we or anyone ever work out what the one used in this product does?


Not to my knowledge...I don't think the manufacturer of Thyroid-S has made the list of inactive ingredients public.


Strange ,YulianaRossenova , i have never ever heard of a shipment of medication being confiscated in the uk.... On what grounds?

Sometimess we get charged duty and handling, but there is no reason for confiscation.


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As far as I know, it's legal in the UK to import non-controlled substances, including prescription drugs, for personal use. It's not legal in most other European countries. I know for a fact that it's not legal in Sweden, Belgium, and Luxembourg which are the three countries I know best, but I'd imagine it's pretty much the same everywhere...not sure about Germany, but maybe someone here knows?


There is no extant patent on levothyroxine or liothyronine in at least the UK and USA.


No, there have been no new preparations of t3 or t4 for a long time and a patent only lasts 20 years. Thats why we now have so many generic versions.


Levothyroxine was never patented in the USA. I have never managed to find a UK patent either - but that doesn't prove there never was one.

We actually have far fewer makes than once we had! I think both the USA and the UK have ended up losing several makes over the last twenty years. (Yes - I have taken into account that several makes changed name so it isn't always clear-cut.)


Out of curiosity, i just had a look round for patents on levothyroxine. Its too late to patent levo, but the drug campanies have decided that its unstable, so there are several patent applications where they have mixed it with other stuff in order to preserve it. Thie things its mixed with include, potassium iodide, cellulose, polyvinil....something. ( isnt that paint?). ... None of this is actually needed, and many of us will have absorption problems...... But the compaies will make more money with new improved versions. Eek!,,,, it just makes me want to grow my own pigs!

Below is an excerpt from a website i found.... I could go through the history and find the url, but am off to bed right now.

.“......Methods used to stabilize levothyroxine in medications have been studied more than

a decade. The leading group in this area is Chen et al (US Patent 5,225,204, July 6,

1993). They stabilized levothyroxine sodium by complex formation using

polyvinylpyrrolidone. Later, Groenewoud et al (US Patents 5,635,209 and 6,190,696

Vintage Pharmaceuticals, Inc.) stabilized levothyroxine sodium using iodide as a

stabilizing excipient. Mitra et al (US Patents 5,955,105 and 6,056,975) stabilized the

compound with a mixture of glycine, a carbohydrate and an inorganic salt. Frontanes,

et al (US Patent 6,399,101) used silicified microcrystalline cellulose to stabilize the

drug. Schreder, et al (US Patent 6,491,946) used a mixture of potassium iodide,

microcrystalline cellulose and binding agent to prepare a stable preparation of

levothyroxine. While, Franz et al (US Patent 6,555,581, Jones Pharma Inc.) prepared a

stable composition using beta-form of microcrystalline cellulose and disintegrant......."


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I can only agree with Galathea. I have been on synthetic T3 (along with T4) in the past, and I am now on NDT (I just switched from Thai NDT to prescription drug Erfa). With NDT, it's a smooth ride, whereas when on synthetic T3, I had the impression I was either slightly overmedicated or slightly under medicated...I never seemed able to get it right. Having said that, I know synthetic T3 (sometimes synthetic T3 only) works wonders for some people, but I'm not one of them...


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