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  • Writer's pictureDr. Jeni St. Onge

Do You Have an Underactive Thyroid?

That is a GREAT question! My specialty is the Thyroid gland… Helping people naturally support good Thyroid health. I am constantly amazed by the number of people who wonder this and have not had a good answer. A REAL answer, based on a complete and thorough evaluation of their Thyroid gland.

What does an Underactive Thyroid gland feel like? Mostly, I hear that low energy and weight gain are the two biggest issues. Brain fog, depression, joint pain, hair loss and trouble sleeping are also common.

The short answer to this question is that in order to know if you Thyroid gland is underactive, you must have it properly evaluated. Not a simple TSH only test viewed through the lens of the “Reference Range” for the lab company. That reference range has nothing to do with your health in the first place. It’s simply a range that most people fall into. If you look around at how sick our population is, I think you will agree with me that we need to ask what a HEALTHY range is for our lab values. Those are referred to as “Functional Ranges” and that is how I interpret lab tests.

So, let’s talk specifically about the Thyroid. A typical evaluation will include usually only a TSH or Thyroid Stimulating Hormone number. This is viewed by many practitioners as the screening tool for a Thyroid problem. As long as that’s “In Range” the Thyroid is fine. We talked earlier about the reference ranges having nothing to do with health, so I see a large number of people with TSH labs in “In Range”, who are actually feeling horrible because that range is not, in my opinion, a reliable marker of Thyroid health. Even when that number is in range, it’s only the tip of a very big iceburg.

How the Thyroid Works

Let’s take a quick look at how the Thyroid works. TSH simply tells your body if you require more Thyroid hormone. The higher this number, the more your body needs. The Thyroid then should respond by producing T4, an inactive form of Thyroid hormone that is converted to T3, the active form of hormone, throughout the day. If you look at the picture below, you will see that the creation of T4 and the conversion from T4 -> T3 requires nutrients that many of us are deficient in. Stress, trauma, toxins and inflammation can also cause issues. So, I think it makes sense to look at T4 and T3 levels. T4 can also convert to Reverse T3, which is an “imposter” form of T3 that can not be used by the body. However, it takes up a spot on the Thyroid receptor sites, so that the T3 we need to create energy can’t reach the cells. This is problematic. This is also why looking at Reverse T3 on a lab test is helpful.

You can see that there is a lot more to this story than simply looking at one lab value and then offering some Thyroid hormone if that value is “Out of Range”. Maybe there are nutrient deficiencies or stress, trauma, infection, etc. that are causing Thyroid hormones not to be properly created and converted. In that case, the real solution is to address those issues.

The Whole Story with Lab Testing

So, if a simple TSH isn’t telling the whole story, what lab values should we be looking at? Here is a list of what I look at when evaluating a Thyroid:


T4, Free and Direct – Free levels are the “useable” levels not bound to blood, so it’s good to see both

T3, Free and Direct – Free levels are the “useable” levels not bound to blood, so it’s good to see both

Reverse T3 – Tells if you are converting too much T4 to this “imposter” version of T3.

TPO and TG antibodies – let you know if your Thyroid gland is breaking itself down. This is an autoimmune condition.

You can see that this list is much more extensive and helps us paint a much better picture of what is going on. This is how we answer the question of whether the Thyroid gland is underactive. I also look at the Functional ranges for all of those values instead of the “Reference Ranges”. This means that I am using ranges that tell if the values are in the optimal or healthy range. It’s a completely different way to look at things, and it makes a big difference!

I find that beginning with a good, complete evaluation of the Thyroid is very important if you are concerned about whether or not you have an issue. I run these tests all the time and frequently find an issue on those who have been told their Thyroid looks “fine”. If you would like to speak with me about that, please use this link to set up a free consultation and I’ll tell you if I think I can help!

I hope you found this article helpful. Please share it with anyone you think might benefit. I am trying to spread the word about good Thyroid health and help as many people as I can optimize their health naturally!

To your health,

Dr. Jeni

This information should not be substituted for medical or chiropractic advice. Any and all health care concerns, decisions, and actions must be done through the advice and counsel of a health care professional who is familiar with your updated medical history.

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