July 19

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Bottom Line – Here is What Your Thyroid Labs Actually Mean

By Sunny Brigham, MS, CNS, LDN

July 19, 2021



Understanding your thyroid labs is a big piece of understanding how and why you feel a particular way. Often, people jump to the internet for help with this. And that avenue may be what brought you here today! 

When it comes to your thyroid labs, there’s not much that goes into it...on the surface. The labs themselves aren’t all that difficult to read. Or even understand what’s happening with them. But fixing them is another issue altogether.

After reading this blog, you’ll have a better understanding of what your thyroid labs mean and know how they affect your Hashimoto’s so you can better take control of your body and your health. 

Thyroid in a Nutshell

Let’s just start with a basic understanding of how the thyroid works. If you understand this, the labs will make a bit more sense.

The entire thyroid process is called the Hypothalamus-Pituitary-Thyroid Axis (HPT). The hypothalamus releases thyrotropin releasing hormone (TRH). TRH stimulates the pituitary gland to release thyroid stimulating hormone (TSH). TSH stimulates the thyroid to release both T4 and T3.

The first point to note is that TSH doesn’t come from your thyroid, it comes from the pituitary gland. The second note is that your thyroid releases both T4 and T3. 

Once the thyroid releases T4 and T3, T4 then gets converted to more T3. T3 then binds to receptor sites to do its thing. Once bound, signals get sent back to the hypothalamus to tell it to start or stop releasing TRH. 

There are a few things that cause a disruption in this process. 
  • T4 doesn’t get converted to T3
  • Hashimoto’s attacks the thyroid slowing the release of T4 and T3

If T4 doesn’t convert to T3, there is no T3 to bind to the receptors and send the signal back to the hypothalamus that all is well. So the hypothalamus pumps out more TRH resulting in more TSH. 

The primary site for conversion is the liver. Not eating the right foods to support your liver will alter this process. Having inflammation will alter this process as well. Taking in too much or too little iodine will have an effect too! Stress can definitely affect this process. 

In the case of Hashimoto’s, the thyroid is being attacked and can’t release enough T4 and T3 to keep up. Without T4 or T3, there’s nothing to bind to receptors. This sends the signal to the hypothalamus that more TRH is needed. This results in more TSH.

Both result in the classic hypothyroid labs...high TSH, high T4, and low T3. 

Thyroid Labs To Request

Now that you have a better understanding of what happens in the thyroid process and what organs are involved, let’s talk about labs that you should be requesting. 

Here is a list of the labs that you should be requesting:

  • TSH
  • Free T4
  • Free T3
  • Reverse T3
  • Iodine
  • Selenium
  • Full iron panel (ferritin, iron, saturation, TIBC)
  • TPO antibodies
  • Tg antibodies

This list is just for the thyroid to see what might be the primary cause. If your TSH is high and your T4 is high as well, your antibodies, iron, selenium, and iodine will clue you in on where the disconnect might be. 

If your antibodies are high, Hashimoto’s may be the primary cause of why your HPT axis isn’t working like it should. But if your antibodies are low or well controlled, the other labs will clue you in.

If selenium or iodine are low, you may need more of those nutrients. Both are very important in the T4 to T3 conversion process. Iron is another very important part of the T4 to T3 conversion process. Coincidentally, low iron is common in those with Hashimoto’s. That’s a story for another day but this is why getting your iron panel completed is important. 

I like to see Reverse T3 for a few reasons. Firstly, it’s a great inflammatory marker. Secondly, it’s an indication that insulin resistance is present. Especially when we look at the ratio between T3 and rT3. 

Ensuring that your labs are run regularly and knowing what they mean gives you control over your body. It tells you where you need to focus your efforts. Is it the liver? Or is it bringing down the inflammation that Hashimoto’s creates? (Hint: It's usually Hashimoto's because that can affect the liver as well.)

T3 and T4 - The Full Story 

T4 and T3 come in both bound and unbound versions. The unbound is free T3 and free T4. 

Bound T4 and T3 are bound to proteins. These proteins aren’t easily removed. This means that T4 and T3 aren’t easily converted or used by the body. If you’re tracking T4 and T3 in labs, you’re looking at the wrong things. 

Free T4 and free T3 are free to be used by the body. They aren’t bound by proteins. They are free and available to be converted and used right away. And this is the best form to track for accurate levels in the body.

I know that many physicians only track TSH or just TSH and T4.

This is doing you a disservice. It’s keeping you in the dark about what’s really happening inside your body. Some won’t run a full panel because they claim insurance won’t pay. This is inaccurate. It’s on the physician to explain why the labs are needed. They may not want to take the time to explain. 

I also feel that many physicians don’t listen to their patients. I’ve spoken with a few physicians for my clients to help advocate for more extensive lab testing. I wonder if it’s this new age where individuals are taking control of their health? Doing their own investigations? Having more access to journals and information? Maybe physicians feel threatened or annoyed by this? Maybe they feel like they’re no longer the expert?

I’m not sure what it is. There will always be a place for physicians in the healthcare system. And patients love physicians who make them feel heard. So, it behooves physicians to listen and be open to testing when a patient wants it. It creates a better experience for the patient. And the patient is likely to keep going back...and refer others to them. 

If you have a physician that won’t run these labs, you can always request them on your own. Insurance won’t pay but you have that option. You can order your own labs to be drawn by Quest or LabCorp through Walk In Lab

Alright...stepping down from my soap box!

Thyroid Labs & Hashimoto’s

You’ll notice that I haven’t mentioned that T4 and T3, or even TSH, play a role in Hashimoto’s. This is because they don’t. Hypothyroid doesn’t create Hashimoto’s. But, Hashimoto’s can create hypothyroid. 

If you have Hashimoto’s and focus on bringing down that inflammation, you’re going to make some alterations to how your thyroid functions. But solely focusing on your thyroid won’t change how your Hashimoto’s functions.

Hashimoto’s attacks the thyroid. When this happens, less T4 and T3 are released. If you want to change the course of how your thyroid functions, you have to focus on the root...Hashimoto’s!

And that’s that! Now you have an understanding of what to look for when it comes to your thyroid labs. The biggest piece that you should understand is that your thyroid labs don’t control Hashimoto’s. But your Hashimoto’s can control your thyroid labs. 


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