is the T4:T3 ratio in NDT wrong?

I just stumbled upon this statement on Ray Peat's website. This statement really surprised me, as it seems to imply that the T4:T3 ratio in NDT is completely wrong and increases the risk of T4 to rT3 conversion:

The naturally found concentrations in the thyroid gland of animals of T4 and T3 are usually in a ratio of 4:1 or 5:1 and this ratio is most commonly found in NDT products like Armour. However, in hypothyroid people this high ratio of T4 to T3 can lead to rapid inactivation of T4 into reverse T3 (rT3) and thus worsen symptoms of hypothyroidism. According to Ray Peat, in hypothyroid states a much more desirable ratio would be 3:1 or even 2:1.

The human thyroid gland does not produce T4 and T3 in a 2:1 ratio, as far as I know, so how can this ratio be the best one for hypothyroid people?

27 Replies

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  • anna69 Just my opinion, but we are all different. Which is why some people do well on NDT, some do better on T4/T3 combo and find the ratio which suits best, and some people do best on T3 only. There is no one size fits all.

    I didn't do well on NDT, nor T3 only, nor a combination of both. However, at the moment I'm on a T4/T3 combo of around 3:1 which I'm not doing too badly on, still tweaking!

  • Interesting! So pretty close to what this doctor (I don't know if he is an MD or not) suggests...?

  • Well, still experimenting. I put up a post a couple of days ago explaining that I'd been on ever increasing doses of Levo for 20 years, with suppressed TSH and ever increasing FT4, and eventually took things into my own hands, albeit cautiously adding T3 and reducing Levo. I am sure, but not 100% positive because I couldn't get the test done before I started adding T3, that I had rT3 over range, I've now tested and it is at the top of range.

    I'm still tweaking, was 100 Levo/31.25mcg T3. Just started 75 Levo/31.25mcg T3 to see if that improves things, so it was 3.2 : 1 but now it's going to be nearer 2.5 : 1. Once the rT3 has reduced (hopefully) I may settle on a different combo. Time will tell.

  • Maybe because, chopping up euthyroid people and desiccating their thyroid is not considered acceptable ? :D

    No it's not the same ratio but for some it works a deal better than anything pharmaceutical companies peddle. :)

  • Its true the ratios are different in humans to pigs. And as with T4 only therapy there will be a theoretical risk that some people will produce excessive RT3. But most do not seem to. The body seems able to regulate its T3/T4 ratio without necessarily resorting to excessive RT3 production in most people.

    However, I wouldn't personally give much credence to any opinion of the man who thinks that all healthy people should be nibbling on a T3 tablet through the day. How irresponsible can you get without being locked up?

    If you have high RT3 on T4 only, then the normal treatment is T3 only.

  • I see...! I have to admit I don't know much about this Dr. Peat. At first, I thought he was the "Dr P" in the UK that many members here were referring to, but I guess that refers to Dr. Peatfield, at that Dr. Peat is in the US? Yes, it's true that he seems a little obsessed with T3 as far as I can tell...I think it was on his forum that I read that a dose of T3 won't last for more than two hours in the body...which would mean you'd have to take T3 at least ten times daily...?!

  • He's a PhD in something or other, not a medical doctor. He has reasonably valid views on PUFAs (polyunsaturated fats) but much of what he is advocating is based on pretty bad science, and he typically quotes one or two cherry-picked studies often on small samples and with poor controls. Or at least that was what I was noticing for the relatively short time I read his stuff. I was introduced to him by a lovely guy with an IQ well below 100, and he generally seems to have a very devoted and unquestioning following.

    He advocates taking T3 for everyone to get their metabolism up. Never mind NDT, what is that going to do to people's ratios? It just beggar's belief. And what about the suppressive effect on TSH of T3? I don't think he has thought that far.

  • Yes, I noticed that about his followers...totally devoted to him, will freak out if anyone is critical of his theories or findings...thanks for the info, now I know I don't have to bother with him anymore.

  • He also thinks that a diet of milk and potatoes is very good for hypos to get the protein they need. That's what struck me most about him.

  • Really Goosie? I missed that bit. Probably as well!

  • lol I read that ages and ages ago. I think it was in an interview Mary Shomon did with him.

  • Plus, he now sells a product OTC, said to be what every hypothyroid patient needs...with a T4/T3 ratio of 2:1. Needless to say, the reviews (on his webpage) are glowing...

  • Well, whatever. He hasn't yet cottoned on to the realisation that ratios for healthy people have nothing to do with hypos. We need what we need, whatever that may be, and not what he thinks we need! His product may suit some people, but it certainly won't suit us all! Perhaps he'll learn from this experience.

  • Brings to mind the phrase Unique Selling Point (USP). Find something, anything, to differentiate your product from all the rest - then promote the hell out of that USP. If successful in the market, others will follow - unless you have locked it up with intellectual property rights.

    Of course, the USP does not need to be of any actual use, benefit or importance. Just needs to lodge in consumers' minds...

  • What I don't get is how he gained credence in the first place. His writings are unreadable, as well as bad science. No-one in their right mind would bother for long.

    Most of the groupies don't read him in the original anyway.

    He is living proof that you don't have to be good at anything to succeed.

  • Well, I think we have plenty of proof of that! lol (Mentioning no names because we mustn't talk politics.)

    Maybe it's the same story as most gurus, he appeared at the right time, in the right place, where there were a lot of desperate people. Desperate people who knew less than he did! Maybe Mary Shomon's interviewing him gave him a certain prestige. Maybe his groupies aren't in their right minds - they are, after all, hypo - and likely to stay that way if they follow his teachings! Who knows.

  • Whenever you read any comment on "the correct ratio of T4 to T3 in hypothyroid humans", just remember that the "gold standard" treatment is a ratio of 100% T4 to 0% T3. Then laugh at whoever is discussing it and do whatever makes you feel well.

  • I know:-) What I meant was (not clear from previous post, sorry about that) that the T4:T3 ratio in a human thyroid is closer to 10:1, not 2:1 as Peat seems to advocate?

  • I think he was making a suggestion about what the ideal ratio is for the treatment of hypothyroid people. I don't think he was suggesting his ratio matched what happens in healthy people. That was my understanding of the bit you quoted.

  • OK, I see...I am just curious how he came to this conclusion...through research, practical experience, etc...?

  • No idea, sorry! :)

  • The ratio in the thyroid is not in itself important. It is how much comes out of the thyroid... This comparison is regularly made, I believe misguidedly.

  • strange but my husband has been on NDT for 12 years and unlike all the miserable years on levo or t3 he is fit and healthy on NDT at age 74

  • About 15 years for me.

  • Good for him. Levo has a lot of side effects.

  • He cannae do the maths, Jim! (Ray Peat, I assume, as it is quoted from his website.)

    Below a table of T4 and T3 content of a variety of desiccated thyroid products. The ratios are expressed in terms of weight and as molar ratios (effectively, number of molecules of each). Nowhere, not even once, does either of the ratios 4:1 or 5:1 appear.

    Make  T4  T3  Weight ratio  Molar ratio

    Nature-Throid  38  9  4.22:1  3.44:1

    Westhroid Pure  38  9  4.22:1  3.44:1

    NP Thyroid  38  9  4.22:1  3.44:1

    Erfa Thyroid  35  8  4.38:1  3.57:1

    Thiroyd  35  8.31  4.21:1  3.43:1

    Thyroid S  38  9  4.22:1  3.44:1

    (Apologies for poor formatting. It is difficult on this platform.)

    It is also wholly wrong to assume that the ratio present is the ratio delivered. In the world of levothyroxine, despite often being ignored, absorption is well-known to be significantly lower than 100%, and almost universally agreed to be lower than for liothyronine. That would affect the delivered dose. Possibly more importantly, the amount delivered varies across people.

    Further, high rT3 is not a symptom of hypothyroidism in itself. Sure, we see many claims that treatment of hypothyrodism can result in elevated rT3. That is not the same thing as making it a primary sign of hypothyrodism.

  • So true:-)

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