Thyroid Health: How to optimize T4 to T3 conversion

Your thyroid gland is a big deal right? I mean what doesn’t it affect? Every cell in your body has thyroid receptors. Without proper action of the thyroid gland and the hormones it produces, all manner of havoc can show up in the body.

From liver and kidney function, to blood sugar regulation, weight gain or loss, hair growth or loss, digestive secretions and digestive motility, brain, and nervous system function, if your thyroid has ever been sluggish, you’ve likely experienced issues in one or more of these areas.

Thyroid hormone conversion

Often when we talk about thyroid function, we focus on trying to get our thyroid gland to produce more thyroid hormone or if you are on thyroid hormone replacement, titrating your dosage trying to somehow alleviate the symptoms of low thyroid hormone activity.

I would like you for a moment to not focus on the little butterfly gland in your neck and instead put your focus on what is happening after T4 is produced by your thyroid gland. This brings us to T3, the most active form of thyroid hormone. Once T4 reaches the liver and kidneys, a portion of it is converted to T3 via an enzymatic process called deiodination. If your liver and kidneys are impaired, this process will be slowed and you will have hypothyroid symptoms because of it. 

Unfortunately,  there is a catch 22 with T4 to T3 conversion, in that, as it slows, so too does our liver and kidney function. When the liver and kidneys are impaired, it causes a decrease in thyroid conversion and this decreased thyroid conversion causes an even greater detox burden on the liver and kidneys. And around and around we go. 

How to support T4 to T3 conversion

If T4 to T3 conversion does not look optimal in your blood work, then be sure to look at supporting your liver and kidneys with food, activity, and herbs.

But also, consider your zinc, selenium, iron, magnesium and vitamin D levels.  Without optimal levels of these nutrients, your T4 to T3 conversion has no chance of being optimal.

Specifically, both selenium and zinc are involved in the enzymatic process that allows for the production and conversion of thyroid hormones.   

Zinc is also necessary for the proper function of the thyroid hormone receptor on your cells.  Without adequate zinc, this cell receptor cannot bind T3 and you cannot get the metabolic signal T3 is trying to bring to your cell.  Hence the brain fog, constipation, bloating, weight gain, hair loss.

Factors that can hinder T4 to T3 conversion

There are many potential factors down regulating T4 to T3 conversion but one I would like to mention is chronic inflammation.

I see this over and over, where chronic inflammation impairs T4 to T3 conversion and patients want more thyroid hormone to help with low thyroid symptoms but this does nothing to help them, in fact it often makes them more agitated.  

One reason why agitation and anxiety seem to rear their ugly head is because under chronic inflammation, the pituitary gland in your brain tends to receive more T3 while the rest of the body is starved of T3. This is also how a person can have a normal TSH, while having low T3 levels on a blood draw.  Since the pituitary gland has plenty of T3, it doesn’t see why it needs to send out any more TSH (thyroid stimulating hormone) to kick up thyroid activity.

If you feel like your thyroid is off, maybe you’re adjusting your thyroid dosing all the time or your labs are all over the place, take a step back and assess your nutritional status related to thyroid conversion. You want to consider any issues related to liver or kidney congestion or detoxification and look at your inflammatory load. 

Do you consume a high processed food diet?  Do you have high stress inputs or poor sleep hygiene?  Are you getting regular physical activity? 

Maybe your thyroid is actually doing its job.  Maybe it is the peripheral conversion that is at fault and creating your symptoms. 

Have you experienced thyroid issues? I’d love to hear what’s worked for you in the comments below.

5 thoughts on “Thyroid Health: How to optimize T4 to T3 conversion

  1. Beethoven

    Thyroid issues well let me tell you after 6 years I now have Hisamoto thyroiditis along with total hormone disfunction. My only relief is in Traditional Chinese Medical Herbs (mushroom) along with lifestyle change but at this point the damage is done and irreversible, but at least my is life is manageable.

    1. Jenna

      Try the Pompa Program! It IS reversible. It’s not too late. I am on the program right now and it takes a few months to really begin to see change but it’s is worth the money I invested. Which was a lot for me. But after 6 years I’m finally seeing a shift!

  2. Rose Hubbard

    I’m on 100mcg. Thyroxine
    My bloods always come back as normal range
    Years ago a doctor put me on T3
    I was still taking my thyroxine
    I felt great
    One morning I woke up and my heart was racing
    So I was taken of T3
    Always remember how good I felt

    1. Martha

      Same. I was taken off for the same reason . And always remember how great o felt on it. Now I fell like garbage .

    2. Lisa

      That’s sad to hear they took you off the T3. I follow a girl who takes both. The T3 made her heart race, but her doctor lowered the dosage of the Synthroid instead of taking her off the T3 and that was the perfect mix. I’m trying to find someone that will consider the T3 medicine as we speak.


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