T3 Test: T3 Thyroid labs, Free T3, and Reverse T3

Feeling lost in the maze of T3 test results and other thyroid labs? You’re not alone. In this episode of Health with Hashimoto’s, Esther, a registered nurse and holistic health educator, will help you understand the complexities of thyroid labs, specifically focusing on T3, free T3, and reverse T3. Esther explains the importance and function of T3, its conversion process from T4, and how our body utilizes it. As always, you will discover simple ways to support your body with the goal of normal T3 test results.

Health with Hashimoto’s is your free weekly podcast to explore the root causes of your autoimmune condition and discover holistic solutions to address your Hashimoto’s thyroiditis.

You will find this episode below in audio format and a written summary because I know not everyone is an audio learner. Some links may be affiliate links that will support me without increasing your price.

Each episode of Health with Hashimoto’s is for informational and educational purposes. Please discuss any questions or concerns with your trusted healthcare professional.

The Holistic Hashimoto’s Course

Recharge Your Energy and Banish Overwhelm

Esther Yunkin, RN barefoot on a woodland trail

Your journey back to feeling like yourself again starts here.

Listen to the Podcast

Subscribe so you don’t miss out

Apple PodcastsSpotifyGoogle PodcastsPodbeanAudibleiHeartRadioPlayer.fmAmazon AlexaYouTube
Three blank keys laying on a white surface. Text reads: Thyroid Tests Explained: T3 Test, Free T3, and ReverseT3

Mentioned on This Episode:

094 // Thyroid Tests Explained: T3 Test, Free T3, and ReverseT3

Navigating through thyroid labs can feel like walking through a maze, right? I mean, T3, free T3, reverse T3—what’s the deal with all these terms? It’s enough to make anyone feel a bit lost. But hey, you’re not alone in this confusion. Even healthcare providers sometimes scratch their heads over which labs really matter.

So, let’s tackle this together, shall we? In this episode of Health with Hashimoto’s, we’re going to unravel the mystery of T3 labs and help you make sense of it all. Because let’s face it, understanding what’s going on with your thyroid is key to feeling your best.

But before we dive into the nitty-gritty of T3, let’s take a step back and remind ourselves: what exactly is the thyroid, and why do these labs matter for our health? It’s all about getting back to basics and making sure we’re on the same page.

Thyroid function

Alright, let’s talk about your thyroid—it’s that tiny gland hanging out at the front of your neck. This little powerhouse is responsible for churning out thyroid hormone, which is a big deal because every single cell in your body has a special receptor just waiting for it. But here’s the catch: your cells want this hormone in a specific form.

When your body signals to your brain that it needs an energy boost, your brain promptly sends a message to your pituitary gland, stationed at the base of your brain. This gland then shoots off a signal known as TSH (thyroid stimulating hormone) to your thyroid, essentially saying, “Hey, we need more fuel!”

Ah, TSH—a familiar term in the world of Western medicine, right? It’s typically the first thing doctors check. You see, the higher your TSH levels, the louder your brain’s plea for more thyroid hormone, suggesting that your thyroid might be falling short.

Now, when your thyroid gets this memo, it springs into action, producing thyroxine,  commonly referred to as T4. But here’s the catch: your cells can’t directly use T4. Nope, they want T3—the real ignition switch for every cell in your body.

So, where does T3 come from? It starts as T4 and is converted to T3 primarily by your liver and small intestine, with some of the transformation happening all around your body in your other organs and tissues.

T3 is the ignition switch for every cell in your body, telling them it’s time to get to work and start buzzing with energy. And when your cells are firing on all cylinders, your organs and tissues follow suit, and voila, you’re feeling like yourself again—energized, alive, and ready to take on the world.

Because let’s face it, we all want to feel like ourselves, right? It’s like getting all your systems back online and ready for action. And trust me, that’s exactly what we’re aiming for.

Cracking the Thyroid Lab Code

Ever been handed a stack of thyroid lab results and felt like you’re reading hieroglyphics? You’re not alone.

When it comes to deciphering thyroid labs, confusion is par for the course. I’ll never forget the first time my provider mentioned checking my thyroid—it was like trying to crack a secret code and I didn’t have the key.

Adding to that confusion, different labs bundle their thyroid tests differently. “Normal ranges” can also vary from one laboratory to another.

But here’s the kicker: even healthcare pros can find themselves in the dark when it comes to thyroid labs. I’ve seen it firsthand working with many doctors and other providers—sometimes, even the experts need a little help. So don’t feel alone if thyroid tests confuse you.

So, let’s cut through the confusion together. Because navigating thyroid labs shouldn’t feel like navigating a maze while blindfolded.

T3 Test

You might think then, since T3 is so important, we’d just test that, right? Well, the first T3 test you may encounter is the total T3. But here’s the catch—it’s not all that helpful unless you’re suspected of having Graves’ disease, an autoimmune condition characterized by excessive thyroid hormone levels.

Now, here’s my disclaimer: while I’ve delved into thyroid studies for years, pulling information from various sources, I can’t pinpoint one specific reference. The same goes for lab ranges—each lab has its own set of numbers. The ranges I provide are based on common functional medicine standards, but remember, there’s often disagreement in the medical community, especially when it comes to thyroid matters. Always check with your laboratory and provider.

When it comes to T3, the optimal functional range typically falls between 100 and 180. If it’s elevated, it might signal an overproduction of T3, possibly indicating Graves’ disease—an issue where your thyroid goes into overdrive.

Unlocking Free T3: The Key to Functioning Well

Free T3 is one of the top two tests you want to look at. Now, you might not always see this test on your lab report unless you (or your provider) specifically request it.

Free T3 measures the amount of T3 available for your cells to use. Ideally, this falls between three and four. Why does it matter? Because T3 is what your cells need to kick into action. Without enough free T3, you might start experiencing those dreaded hypothyroid symptoms—weight gain, a sluggish metabolism, constant coldness, constipation, depression, hair loss, skin issues, sluggishness, brain fog, and more.

Imagine feeling like you’re running on empty despite your TSH levels appearing normal. That’s where free T3 comes in. It’s the missing puzzle piece that could explain why you’re still feeling off.

But here’s the million-dollar question: if your thyroid produces enough T4 (or if you are taking a T4 medication like Synthroid or Levothyroxine,) which should convert to T3, why the shortage?

Reverse T3 and What Causes rT3 to Go Up

When your body signals it’s time to slow down and heal, it can produce reverse T3, acting like a brake system. While some reverse T3 is normal, chronic stress, acute stress, inflammation, trauma, or even certain medications like beta blockers can spike its levels.

Your body aims for balance, but heightened cortisol or low iron levels can disrupt this equilibrium. For instance, low cortisol can cause excess T4 to build up in your blood, prompting your body to produce more reverse T3 to manage the surplus. Similarly, low iron levels can reduce blood cell counts, leaving excess thyroid hormone in circulation, thus triggering an increase in reverse T3 production to counterbalance.

Even medications like beta blockers, often prescribed for heart conditions or blood pressure, can elevate reverse T3 levels, contributing to thyroid imbalances.

What is Leading to Your Abnormal Thyroid Tests?

To address imbalances in thyroid hormone levels, it’s crucial to tackle root causes. Stress, a common culprit, can lead to elevated reverse T3 levels, hindering thyroid function. In the Holistic Hashimoto’s Course, you will work on your root causes including stress.

But what if your lab results show low T3 or high reverse T3? Identifying the underlying causes is key. While you work on these factors, it may be necessary to discuss adjusting your medication therapy with your doctor. Finding the right medication regimen is highly individualized. Some thrive on T4 alone, while others benefit from a combination of T4 and T3 or even no medication at all. The goal is to find what works best for your body.

If insufficient T4 is the issue, medication like Synthroid or levothyroxine may be necessary to provide the necessary T4 levels. If your body is not converting T4 to T3, you may benefit from a combination approach like natural desiccated thyroid (NDT) or Armour Thyroid. Ultimately, addressing the root causes behind conversion issues is crucial for optimal thyroid health. Since most conversion takes place in your liver and gut, let’s start there.

Supporting Your Liver so it Can Convert T4 to T3

Liver health is paramount for thyroid function, as this vital organ plays a crucial role in hormone processing, particularly estrogen. When the liver struggles to process estrogen efficiently, it can lead to estrogen dominance, placing added strain on liver function. To support your liver, consider implementing strategies discussed in my podcast episode on estrogen dominance, where I delve into liver health and its impact on hormone balance.

One simple yet effective way to support liver health is through supplementation. I incorporate Protandim NRF2 into my daily routine. This supplement contains a blend of five potent herbs that activate the body’s natural detoxification processes, including the production of antioxidants like glutathione. Glutathione is instrumental in detoxifying the body and maintaining overall health. By activating NRF2, your body can increase glutathione production by a remarkable 300%, supporting liver function and various detox pathways essential for overall well-being.

Prioritizing liver support is essential to ensure optimal thyroid function. By nurturing your liver’s health, you empower it to perform its vital role in hormone conversion and detoxification, ultimately promoting holistic wellness.


Optimizing gut health is essential for thyroid function, as the majority of T4 to T3 conversion occurs in the small intestines. Therefore, prioritizing gut health is key, and one effective way to do so is by incorporating prebiotics and probiotics into your daily intake. Prebiotics are fibrous foods that create the food needed for the good bacteria (aka probiotics) in your gut. Probiotics can be obtained from fermented foods or supplements, both of which support the balance of beneficial bacteria in the gut.

I integrate fermented foods into my daily diet, including sauerkraut, yogurt, and kombucha, to provide a natural source of probiotics. Additionally, to ensure optimal gut support, I complement my dietary probiotic intake with a daily probiotic capsule.

Among the various probiotic options available, I choose Seed for its unique formulation containing both prebiotics and probiotics in a single capsule. This innovative approach ensures optimal gut health by providing the necessary fuel for beneficial bacteria to thrive. The synergistic combination of prebiotics and probiotics in Seed supports digestive health and overall well-being, making it an integral part of my daily routine.

Putting it All Together: Thyroid Function, Thyroid Tests, and Healing

Understanding the complexities of thyroid function is crucial for effectively addressing imbalances. Your thyroid gland produces T4, which must be converted into T3 by your liver and small intestines to be utilized by your cells. T3, then, is essential for overall well-being.

If you find yourself lacking sufficient T3, it could be due to factors such as elevated reverse T3 levels or inadequate conversion. Identifying and addressing the root cause of this deficiency is paramount. Medication may be necessary to bridge the gap and it’s essential to view medication as a tool for support rather than a sign of failure.

If you’re navigating thyroid imbalances and seeking comprehensive guidance on addressing root causes, I invite you to join me in the Holistic Hashimoto’s Course. In this course, we explore the underlying factors contributing to thyroid dysfunction and empower you with practical strategies to support your body’s natural healing processes. Together, we’ll work towards optimizing your health and achieving lasting wellness. Join me on this transformative journey toward your best health yet.

Esther Yunkin, RN speaking to a woman holding a coffee mug. Both seated on a couch.

Download the Health with Hashimoto’s App

Unlock your wellness journey with the free Health with Hashimoto’s app!

Join a supportive community that’s here for you every step of the way.

Binge your free mini-course, Hashimoto’s Decoded, designed to answer your questions and cut through Hashimoto’s confusion.

Ready to take control of your health and feel like yourself again? Enroll in the full Holistic Hashimoto’s course.

Download the free app now and get started!

iOS users – look for the Health with Hashimoto’s app.

Android users – Esther is working on your stand-alone app. In the meantime, you can find it via the Passion app.

Take the free Hashimoto’s Decoded min-course

Esther holding a coffee cup that says "make it happen" with title of: Hashimoto's Decoded: Clear steps to regain control of your health

Images used in this post by Florian Berger on Unsplash

Watch via YouTube