young woman self examination thyroid gland

What is Reverse T3 and Why Is It Important to Test?

Written by Guest Blogger: Dr. Tabatha Barber, a triple board-certified in obstetrics and gynecology.

This week, I’m going to be talking about what the heck is reverse T3. I’ve been getting this question a lot and it’s really important for you to understand what reverse T3 is. A lot of conventional doctors don’t get trained on reverse T3. I didn’t really learn about it in any depth and I definitely didn’t learn how to test for it or how to treat it.

Your Thyroid Function 

It can be a game-changer in your thyroid function. Thyroids are not made to just poop out and stop working. That is not how God created our bodies. Our bodies are meant to be amazing at maintaining homeostasis and staying in balance. Our thyroid is our master gland. It will take on the burden of your other systems at the detriment of itself to keep the overall balance of your body. If you are struggling with hypothyroid issues or you’ve been told you have hypothyroidism there is a reason. Thyroids don’t just stop making thyroid hormone because they’re tired of making thyroid hormone. They don’t make thyroid hormones in sufficient quantities because they don’t have the ingredients. Meaning they don’t have the amino acids, iodine, or the vitamins necessary for that production. Or they don’t have the ability to convert thyroid hormone that they’ve made to utilize it, the cell can’t hear the signal because the cell is inflamed, or you’re making too much reverse T3. 

woman exposing her throat while holding white flower

Problems with Your Thyroid

If you’ve been diagnosed with hypothyroidism, or you think you have hypothyroidism, find out why. Ask your doctor and you will probably get, “I don’t know you just have a sluggish thyroid.” Or you might get, “Well it could be an autoimmune process but there’s really no point checking that because there’s nothing to do about it.” Those are the most common responses and are responses I myself gave as a conventional doctor back in the day. I apologize for that because that’s not true. We do know that it’s very important to know if you have an autoimmune attack on your thyroid. Meaning your own immune system is attacking your thyroid. That needs to be stopped and once that stops, your thyroid can probably function again and you don’t need thyroid support with thyroid hormone.

Other reasons for your thyroid might not be functioning well is your adrenal glands are working overtime or they are no longer producing the cortisol and the DHEA that you need them to. It could be that your sex hormones are imbalanced, like your estrogen, progesterone, and testosterone. Or it could be that you have a high toxic burden. If you have too much lead in your system, mercury, or mycotoxins from mold, it could be that you’re getting exposed to too many halogens in your water. Fluoride in your toothpaste and in your water competes with iodine. 

Iodine is a halogen. Thyroid hormone T4 is four iodines, T3 is three iodines, and T2 is two iodines. If you remember back in high school chemistry, halogens are all in the same column on the periodic table. Those include fluoride, chlorine, bromine, and iodine. Those other halogens can compete for the spots where your iodine is trying to go to make your thyroid hormone. Bromine in particular is in high quantities in our processed foods, especially breakfast cereals. They actually add bromine as a preservative. It’s high levels in Mountain Dew as well. So your processed food could be causing your hypothyroidism. I know that was definitely contributing to mine. 

Another big piece was chlorine. I swam a lot and I was in a lot of chlorine and that can compete with your iodine. It’s also in fluoride like I mentioned in your toothpaste. When I was growing up, we had fluoride swishes every Friday at school and we had fluoride treatments at the dentist. So I had all of those halogens competing with my iodine for my thyroid production.

Learning About Your Thyroid Function 

Head over to  YouTube to see the picture that I am talking about. This is your thyroid gland and it produces T4. The brain secretes TSH, that’s the main blood draw that your doctor will check to tell you whether your thyroid is functioning. TSH is a thyroid-stimulating hormone and it’s actually a brain hormone. It’s not even a thyroid hormone. TSH comes down from the brain tells the thyroid to make more or less T4. Your thyroid hopefully will make T4 if you have enough iron, iodine, tyrosine, zinc, selenium, vitamin E, B2, B3, B6, C, and D. 

Things that inhibit thyroid hormone production are chronic stress, cortisol production, infections, trauma, radiation, medicines, fluoride, halogens, toxins like pesticides in your food, mercury, cadmium, lead, and autoimmune processes. So not just an attack directly on your thyroid, but an autoimmune attack at all, anywhere in your body can prevent your thyroid from making thyroid hormone such as celiac disease, lupus, or rheumatoid. 

T4 has to go down and be activated by T3. T3 will bind to all the millions of cell receptors and send the signal to increase your metabolism or decrease it. It will also increase or decrease your thermostat. You have to have adequate amounts of selenium and zinc for this conversion to happen. Then at the cellular level, you’d have to have adequate amounts of vitamin A and zinc to hear the cell signal. You also have to have healthy mitochondria. Mitochondria are the little powerhouses inside your cells that create energy. Those are healthiest and functioning and reproducing from exercise.

Exercise is key to thyroid function and hearing signals from your thyroid hormone. 

Let’s get to this RT3, this reverse T3 because your T4 can go down the reverse T3 pathway instead of the active T3 pathway if you are in a stressful condition. Sometimes conventional doctors will measure it in situations like the patient is in the ICU. Your reverse T3 is going to be really high if you’re in the ICU because it gets produced under times of physical, mental, or emotional stress, chronic cortisol, adrenaline production, or any kind of physical trauma to the body. 

How Your Diet Affects Your Thyroid

A consistent low-calorie diet can cause elevated reverse T3. So just calorie restriction is not good. That is how your metabolism ends up getting turned down and the weight that you have lost by being on your low-calorie diet, all of a sudden comes back and you regain that weight. Because reverse T3 is having the opposite effect on your cells it’s sending the opposite signal of active T3. Reverse T3 slows down your metabolism, your hair stops growing, your skin isn’t getting nourished, and it slows down the bowels. You end up with hair loss, constipation, weight gain, and feeling cold all of the time. When your reverse T3 is elevated. You could have a normal TSH, T4, and T3 level in your blood. They’re not going to be optimal, but they’re going to be normal by conventional standards. 

This is elevated from multiple things such as infections, kidney or liver dysfunction, medications, and alcohol use.  As a functional doctor, I love checking reverse T3. To me, that is a marker of systemic inflammation, toxic burden, and thyroid dysfunction. If it’s over 15, we have some work to do. 

woman doing thyroid self examination

Your Thyroid Is Complex

It’s really important to realize that your thyroid is so much more complex than conventional medicine will have you believe. It’s not just TSH and free T4. I mean, all of our other systems impact the thyroid. The thyroid takes on the burden of the other systems. Say that you are in starvation mode or you don’t have food available that you can eat. Your body doesn’t want to maintain that same high metabolism that you have because then it will start to break down your own muscle for protein and you will become malnourished and sick. The thyroid will turn down your metabolism in an effort to slow your energy production and your energy requirements to sustain that stressful situation. The same thing happens when you have surgery, are sick, you have too much mercury exposure from the food that you’re eating, or you have mercury fillings removed inappropriately. 

Your thyroid is always trying to keep you balanced overall. It’s not that it’s not doing its job, it’s doing what it feels is the best for your body at that time. If we fight it all the time living high crazy, stressed-out lives, we’re pumping out cortisol all day. We’re going from dusk till dawn and doing all the things, our thyroid has to keep a balance overall. So it will adjust those signals and make less thyroid hormone because it’s being shunted down the reverse T3 pathway and reverse T3 become dominant. 

To Wrap It Up 

I hope that you got something out of this today. It’s really a complicated situation, but what I want you to take away is that your thyroid just doesn’t stop working for no reason. There’s always a reason. If you can figure out that reason, remove it, reverse it, support it, and do whatever needs to be done, your thyroid can almost always go back into balance. I have had many people come off thyroid hormone. I myself came off with thyroid hormone. I really want you to have hope that you can support your body to function in the way that God created it to function and it can be amazing. 

Guest Blogger,

Dr. Tabatha Barber

FREE: The Gutsy Gynecologist’s Guide to Balancing Your Hormones

Dr. Tabatha Barber is triple board-certified in obstetrics and gynecology, menopause, and functional medicine. She has the unique situation of being licensed to practice medicine in over half the country, so you now have the ability to work with a functional physician virtually. She is the host of The Gutsy Gynecologist Show; where she shares her wisdom and unique perspective with women everywhere to reclaim their health. She is also a keynote speaker, mentor, wife, mom, and grandma! By incorporating functional medicine into her women’s health practice, she is able to provide women with the tools they need to optimize their health and happiness, which, in turn, allows those women to pursue their purpose in life.

P.S. Catch Dr. Tabatha’s interview in this week’s episode of  The Hormone P.U.Z.Z.L.E Podcast – Functional Gynecology and Hormone Imbalance. You can also find the episode on this podcast page as well as Spotify, and Stitcher.  Don’t forget to subscribe, follow, and write us a review on Apple Podcast (if you LOVE it).

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