McCall McPherson explains how your thyroid works: TSH signals the gland to release T4, which your body converts to active T3. But stress, inflammation, and poor sleep can trigger reverse T3 instead, blocking T3 and leaving you symptomatic even with normal lab results on Synthroid alone.
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Let's do a quick refresher on how your thyroid works so that when you download the thyroid lab guide, it makes a little bit more sense in your head. Okay. So brain sends a message to your thyroid by way of TSH thyroid stimulating hormones. So that's a straw, right? Stimulates your thyroid, really? This tells me two things. It tells me how hard your brain is asking your thyroid to work and how much physiological energy is being put in to get whatever output hormones you're getting out of your thyroid. Makes sense. So this then stimulates your thyroid and your thyroid secretes a hormone called Free T4. So Free T4, again, your thyroid crude oil, Right? So this really is not reflective of how much active thyroid hormones you have. This is your precursor hormone in the same way that we can have all the crude oil in the world, but unless we can convert it to gasoline, it's not really going to do us any good. We can't put it in our car and go anywhere. It's not useful. Right. So T4 does not make us feel good. It does not get rid of our thyroid symptoms. It's simply a marker and a measure of our reserve of how much T4, how much reserve we have to convert to T4. Right. So this is also PS what syndroid, levothyroxine, tyrosine, levoxyl are. So they're all T4. So if you're on those medications and you poorly convert, you have a difficult time converting. Expect that to look great and fantastic. Another reason why your doctor will not really know why, or he or she will say, it's not your thyroid. That's not the reason you're fatigued and foggy and depressed and have no sex drive. Your thyroid labs look great because your TSH looks fantastic and your T4 looks fantastic. Mainly because if you're on those medications, your TSH is largely responsible to your level of T4. So it's sending a message back to your brain and lowering your tsh. So of course your lab numbers look fine. Right? Then your T4 goes one of two ways. It either becomes activated and becomes your thyroid gasoline, your active thyroid hormone, which is free T3, or it gets shunted to an inhibitory mechanism called reverse T3. Remember, reverse T3 serves your body. When we're inflamed, when we have poor micronutrients, when we're stressed, when we don't exercise, when we're not sleeping, when we're sick, when we're pregnant, our body starts driving up reverse T3 to inhibit the absorption of T3. Because remember, it's a mirror image. It's just T T3 in reverse, just like our hands. That allows it to bind to the same receptor site. And instead of activating it in the same way T3 would, it blocks it and keeps free T3 from binding. So the higher this number is, the lower absorption of T3 you're getting. So when you're sick, stressed, micronutrient depleted, our body drives up reverse T3. Why? To make us tired and to make us go into recovery mode. Right. So people on Synthroid or levothyroxine on T4 based medications that poorly convert end up with a lot here of T4 and a lot of reverse T3 because they're poorly converting. So very little is ending up at T3. So that's your little reflection.
