Thyroxine-binding globulin

Different bus, same deal, different hormones.

[laughs] Your liver produces a protein called thyroid binding globulin, uh, TBG, and TBG carries thyroid hormones through your bloodstream.

Most of the thyroid hormones circulating in your blood is bound to this transport, these transport proteins, and only a small fraction is free, and when you swallow estrogen, that increased liver exposure can stimulate the production of more TBG and SHBG.

So now you've got more binding protein available to bind thyroid hormone, and this can reduce the amount of free thyroid hormone circulating in your bloodstream, which could cause a whole slew of pro- problems, including weight gain.

So now we've got higher levels of estrone, possibly more inflammation, possibly more fat because of it, which is then producing more estrone because we m- make estrone out of the fat tissue, and then you're gonna be binding up your poor little thyroid hormones and causing even more weight gain and inflammation.

So this is just like, there's no win here for oral estrogen.

I don't care what any practitioner says, [laughs] I'm not using it, and I don't recommend my clients to use it either.

Now, because increasing TBG can sometimes increase the amount of the thyroid hormone replacement a woman needs, you want to be watching if you are taking oral.

Now, this mainly happens with oral estrogen, which we don't use because we know that oral estrogen increases your risk of blood clot and stroke.

It will also increase your sex hormone binding globulin, and it will increase your thyroid binding globulin, TBG.

And what this will do is it will bind to your thyroid hormone, increase sex hormone binding globulin, will bind to your testosterone, and then we will see a, a, an increase in symptoms simply because of the delivery method or the binding effect of that estrogen.

Now, it is important to note that even patch delivery or cream delivery of estradiol can still increase SHBG.

So keep those nutrients flowing in.

Uh, if you've got high TPO, so if you have high thyroid antibodies, um, or high thyroid binding globulin, it's a TBG.

So, um, you're going to have more, more of that stuff sucked out.

Um, the higher the antibodies and things like that, that we've got, the more I would lean harder on inflammation and, um, insulin resistance.

How so?

Well, the vast majority of circulating thyroid hormone is bound to transport proteins, primarily thyroxin-binding globulin, or TBG.

Right.

In a healthy patient with an intact thyroid gland, any fluctuation in TBG is just met with a compensatory shift in endogenous hormone production.

So the body just makes more to maintain free T4 levels.

Exactly.

Because their gland isn't responding.

Right.