The Missing Piece For Your Thyroid Health That Your Doctor Doesn’t Know About

Have you ever heard of the deiodinase gene?

Before a couple of weeks ago, neither had I, despite the fact that it showed up on my gene test from 3×4 as containing a SNP (otherwise known as a “variant” or “mutation”).

Now, if you have thyroid issues (the literature shows that at least 1 in 8 women will develop thyroid problems in their lifetime, but a LOT of thyroid issues go undiagnosed), you’ll want to pay close attention.

Genes and Enzymes, Oh My

The deiodinase family (DIO) of enzymes is what activates and deactivates thyroid hormone. That basically means your thyroid won’t work properly without DIO1, DIO2, and DIO3 doing their thing.

DIO1 oversees how much thyroid hormone is being produced by the thyroid gland, DIO2 is responsible for most of the conversion from inactive T4 hormone to active T3 hormone, and DIO3 inactivates thyroid hormone by changing it to reverse T3.

Guess who had a SNP/variation on their DIO2 gene? THIS GIRL.

Now, if you were like me just a few years ago, I had no idea that we produce mostly inactive T4 hormone from our thyroid (think of this like having a bunch of grains and water just chilling. Not very enticing to drink, right? But add some bacteria that produces enzymes which creates the fermentation process, and a few days later you are going to have a yummy alcoholic beverage, correct? Much more enticing).

Similar to how the grains and water aren’t great to drink on their own, inactive T4 hormone doesn’t do much of anything for our metabolism. It needs the DIO2 enzyme to convert to active T3 hormone. Active T3 hormone is what:

    • Gives you energy
    • Regulates body temperature
    • Maintains normal weight for your body
    • Supports your hair, skin, and nails
    • Makes your brain work properly

With a DIO2 enzyme variation, you will likely see lowered Free T3 levels on testing because your T4 isn’t converting well to T3, even if your TSH and Free T4 are normal.

What This Means

Here’s a couple of problems:

    1. For thyroid testing, most doctors only test TSH, or if you’re lucky, Free T4. The ranges for “normal” TSH are pretty large, which can hide underlying issues. So many of you are missing out on seeing your Free T3 level, which is actually the *most* important marker to see.
    2. The majority of allopathic doctors and endocrinologists will only prescribe T4 medication (Synthriod/Levothyroxine) for hypothyroidism. But if you have a DIO2 gene mutation, that medication is going to do jack squat for you.
      This is why many women only see a slight improvement – or no improvement whatsoever – after going on hypothyroid medication.

For me, realizing I had this gene variant explained why I’ve always had optimal Free T4 on testing, but low Free T3, despite the fact that I use nutrients to help the conversion process.

So what’s the answer? Those with this gene mutation will most likely need additional T3 medication (Cytomel/liothyronine) on top of a full-spectrum thyroid medication like Armour or NP Thyroid (natural dessicated thyroid).

It’s important to work with a functional doctor who understands the need for additional T3 in these situations (I decided to work with a doctor through Paloma Health).

Making sure your thyroid is working correctly is SUPER important particularly as you move into perimenopause, as perimenopausal symptoms can be much worse with low thyroid function.

And yes, I utilize 3×4 genetic testing with clients who are interested in understanding where they need extra support, from thyroid function to cardiovascular health to bone strength and beyond. Feel free to reach out if you are interested in testing.

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