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Thyroid UK
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Found this on the Ray Peat forum...is it true?

This was one of the answers to the question why NDT might not work for some, and why a combination of synthetic T3 and T4 is sometimes preferable to NDT:

The problem with NDT is that the animal hormones are bound to thyroglobulin and unless that bound is broken the hormones are pretty much inactive. This gives the body a very easy way out if it doesn't want to increase metabolism for whatever reason.

When you take synthetic T4 and T3, you take 'free' hormones. They cannot be (very easily) inactivated.

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I haven't read this before and I wouldn't argue with his viewpoint. I have tried quite a few combinations myself, T4, T3/T4, several NDTs and T3 only. :)


Please refresh my memory, which one(s) do you prefer?


My body prefers T3.

If someone isn't improving on the one they're on at present they're just desperate to try anything else, but the one that's making them feel worse than before diagnois. Or are surprised that what has been prescribed to to remove symptoms has given them more :)

This took me quite a number of years as sometimes there's no 'quick fix' unfortunately if levo isn't improving health. There was also no forum.

(I have no medical qualifications).


This is a half baked concept. Synthetic hormones are free when ingested but get bound pretty soon, otherwise your fT4, fT3 would be massive. I guess there's a slight possibility the NDT may be bound to different proteins to humans but years of use suggest there isn't a problem. Ultimately the fT3, fT4 figures show how much free hormone you have!


I think it all depends on if you convert well with NDT. It is unmistakably the ft3 bit that's the most important to making you feel better but if you don't convert well then there is no point in NDT at all. Or you may just want to cut out the middle man and take the t3 instead. It's a quicker process.


Looks like extremely poorly thought through statements.

It is not clear if he is saying that the thyroid hormones bound to thyroglobulin are in the gut - or have passed through the gut wall. Is this "easy way out" absorption from the gut? Or what? Is it even possible for bound hormone (i.e. the complete thyroid hormone + thyroglobulin molecule) to pass through the gut wall in any circumstances?

We see very clearly that when we take free thyroid hormones, the Free T4 and/or Free T3 levels rise - then fall. Part of that is likely binding of excess free hormone, part using up some free hormone. Free/Bound is a dynamic state.

If nothing else, it really does not add to our understanding one jot.


If you take NDT and your FT4 / FT3 levels rise, wouldn't that be proof that the hormones are at least free enough to get out of the tablets into your blood stream?


This explanation doesn't hold water! In NDT the hormones may well be bound to thyroglobulin, but stomach acid and protein-dissolving enzymes will steadily release the bound hormones. However, NDT has the advantage of providing a natural "slow-release" format as the thyroglobulin degrades, unlike synthetics which are immediately available. So there is a better control of uptake with NDT, and this will be affected by stomach acidity. With PPI's that reduce stomach acid, the T4 and T3 may not be so quickly released in the stomach but they will then be released in the small intestine lower down. Perhaps why some prefer NDT over synthetics is that their bodes prefer slow release over "spiking".


This sounds very reasonable indeed! ;-)

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With Uni-Pharma T3 I feel some gastric distress and, within an hour, a "woosh" in my legs, which have oedema. Not so, with a Thiroyd dose providing more T3.


I am about to try NDT again for this very reason...my body hates the surge of free hormones I get from synthetic t4 and t3....even tiny doses make me break in to a massive sweat and therefore my overall thyroid hormone levels remain too low as I can't tolerate ingesting much. I tried NDT before but I think I had an autoimmune response i.e. a very very sore throat but time to try again so I can benefit from slower release.


Just wanted to say I used to get massive sweats on when I split dosed my t3. I started dosing the full dose once daily early morning and it made a huge difference. No sweats, temp is very level. The once daily full dose carries me through until next morning dose with no high peaks or problems like one might think. My body utilises it by saturating my Cell's. It's remarkable.


Now I am totally confused: my OB-GYN sent me to the lab, and told me it did not matter which day of cycle I went there. So I had blood drawn on day 17 of cycle.

The reference ranges for estradiol during the luteal phase (which day 17 of cycle must be?) are 21-312 pg/mL. Mine are 525, so above range (ref ranges for ovulatory peak 38-649).

Should I interpret this to mean that am estrogen dominant and not deficient...?!

That could explain why I have felt better since going on Duphaston and stopping estradiol. I normally use Oestrogel from day 5-25 of cycle, but stopped on day 15 this time, 48 hours before going to the lab. From what I've read, that should be enough time to clear the exogen estradiol from my body.

Both my FSH and LH levels are in range: both came back at 2.7 UI/L and should be 1.4-5.5 and 0.6-14 respectively during the luteal phase.

About my thyroid labs: I have been feeling really well lately, neither over- nor under medicated. My FT4 levels came back at 1.2 (ref 0.7-1.5) so just above mid-range, but my FT3 levels were 3.6 (ref 1.7-3-7) 24 h after latest dose...so I should assume they were about 20% higher on the previous day, so slightly out-of-range. Should I care about that when I feel fine...?

Any input would be greatly appreciated.


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