T Nation

A Question About Thyroid Hormones


As I understand it there are two hormones produced by the thyroid. One increases metabolism and the other is an inhibitor/regulator for the first.

So in essence, substance one is produced in an amount of 20ppm, but only 10 ppm is required, so a response of substance 2 blocks the usage of 1 of the 20 ppm.

I know someone who has hypothyroidism. But whenever she is given Synthroid etc her body simply increases the inhibitor and the effect is cancelled out.

My question is this.. Is there a compound that can block substance #2 in this scenario?


This post was flagged by the community and is temporarily hidden.


Synthroid is T4 and T4 is regulated by the body. Take T4 and TSH will be reduced. Then the thryoid makes less T4, but that also reduces T4-->T3 conversion in the thyroid.

Synthroid is dangerous as it reduces T3 and Synthroid should never be used alone. That can produce horrible results. But drug reps tell docs to script Synthroid and great harm is done.

All of this must be read:


scary ass shit, thyroid hormones arent worth it unless your a competitive bodybuilder.


... or your thyroid isn't working properly in the first place.


As with many other things, it depends on whether one knows what one is doing or not.


First off, messing with your thyroid hormone levels could have long lasting effects. Having said this, some informed users have reported some success with using T-3 for fatloss (anecdotally). If you do not know what you are doing, or have no clue as to where your current values are, you have no buisness using this stuff. Please also remember I am by no means an expert on this subject, but have done quite a bit of research on the subject.

Enough with the safety stuff for now. . .

There is much more to thyroid than is discussed on the boards, or in the community as a whole. While this may be old news to some, there are also T-2s to think about as well (along with T-1s and T-0). There is no current literature to be found (by me at least) on T-1s or T-0s in pubmed. I have, however found a couple of interesting studies on the T-2s (AKA 3,3 diiodolthyronine and 3,5 diiodolthyronine). One of these papers is titled "How the thyroid controls metabolism in the rat: different roles for triiodothyronine and diiodothyronines", Journal of Physiology (1997), 505.2, pp.529-538. And also "Calorigenic effect of diiodothyronines in the rat" Journal of physiology (1996), 494.3, pp.831-837. Both of these studies reported effects of the T-2s on different tissues and resting metabolic rate. What I have gleaned from this is that the both of the T-2s increase metabolic rate in specific tissues of the body (specifically brown adapose tissue AKA BAT, and the liver). These also seem to have very little effect on cardiac muscle (where T-3 is speculated to have an effect here). The studies also show more effects for a higher dose (dose dependant), and quicker onset of increased metabolism (24hr onset vs up to 72hrs for T-3). There are a few things to mention about these studies though. #1 they were conducted on rats only. #2 the T-2s were injected IP. #3 there was no actual measure of fatloss whatsoever. So please take these for what they are.

On a similar note, there are products on the market containing T-2s as a primary ingredient (OTC supplements). I have even heard that Biotest has at one point dipped its toes into this pool. any truth to this?



Yes, I believe (but could be mistaken) that in fact we introduced T2 to the market.


One of my main concerns is the quality of the hormones sold.

Human grade I wouldn't worry about much, but most people cant get that.

I dont see it as being that useful, in my experience low cals, low carbs, and AAS produces incredible results.

Adding thyroid hormones to that might take you another 1% bf lower, and it might take you there faster with less strict dieting, but it just doesnt seem dramatic enough for me to justify usage, especially since you always lose more muscle with it than without.


Synthroid is problematic for some people as it only has T4. Dessicated thyroid (Armour) or straight T3 usually helps these patients as I understand it. Unfortunately, too many drs only rely on the TSH level to determine dosage even though the patient is still suffering syptoms. Cortisol should probably also be looked at.

Sometimes that is also low and increasing the metabolism makes that worse as more cortisol is cleared from the system. This can cause one to mistakenly conclude the thyroid medication is not working. It shouldn't be assumed that cortisol is low though, it needs to be checked.

My fiance has fibromyalgia, so I've been doing what research I can online. Dr. Lowe and Stop the thyroid madness have been been helpful and we hope to have her issues dealt with in a year or so.