Tag: T3 | Page 3 | Dr. Westin Childs: Thyroid Supplements & Thyroid Resources
Why free T3 and total T3 are the most important thyroid lab tests

Why Free T3 & Total T3 are the Most Important Thyroid Lab Tests

The free T3 and total T3 lab tests are among the most important for evaluating thyroid function in your body.  These tests give vital information as to how your body is processing thyroid hormones.  And they give you information about the hormone which is responsible for activating your cells and turning on your genes.  These …

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T4 to T3 conversion_ factors that decrease thyroid function

T4 to T3 Conversion: Factors That Decrease Thyroid Function

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Evidence-Based

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This is lesson #5 in the thyroid beginner series. 

As you know, this series is designed to help you understand the most basic concepts about thyroid function so you can be a better advocate for your own health

Today is all about T4 to T3 conversion. 

This is the process by which your body creates and activates thyroid hormone. 

It’s important because there are steps that you can take to actively enhance this conversion process and help reduce (or improve) your symptoms. 

Let’s jump in: 

T4 to T3 Conversion Explained in Plain English

This is really a continuation of the concepts that were built upon in lesson #3 and lesson #4 which discuss T4 and T3 thyroid hormones. 

They are short videos (less than 10 minutes each) so if you don’t feel like you have an understanding of thyroid hormones then go watch those before you jump into this lesson. 

As I stated previously, T4 to T3 conversion is the process by which your body takes inactive thyroid hormone and activates it (1).

This process is also known as thyroid conversion or peripheral thyroid conversion but don’t let this confuse you because they are all referring to the same process. 

In this conversion process, your body takes T4 thyroid hormone, which it either produces on its own or that you’ve taken by mouth, and cleaves off a portion of the molecule which changes its shape and structure. 

This change alters the hormone to T3 (triiodothyronine) which is the active thyroid hormone. 

Why is this important?

Because the more T3 you have in your body the better your thyroid functions

The less T3 you have in your body the more symptoms you will experience

What that means for you is that you want this process to be working at 100% because if it isn’t then you will be producing less active thyroid hormone. 

It turns out that the way that your body increases or decreases this conversion process is through the activity of special enzymes

These enzymes, known as deiodinase, are responsible for “cleaving” off an iodine moiety on the T4 hormone. 

T4 is named T4 because it contains 4 iodine portions on the hormone base. 

Once it loses an iodine portion it now only has 3 and we call it T3. 

Approximately 80% of the T3 in your body is created through this conversion process which means it’s very important for thyroid health. 

This conversion process matters if you have a thyroid, if you don’t have a thyroid, if you have Hashimoto’s, if you have thyroid nodules, if you have thyroid cancer, and so on. 

Basically, it matters for everyone.

Why?

Because even if your thyroid isn’t working you still have to take thyroid hormone by mouth and most thyroid medications contain T4 (not T3). 

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Factors that DECREASE T4 to T3 Conversion (These slow down thyroid function)

There are certain factors that can slow down the conversion of T4 to T3 by interfering with the efficiency of the enzymes responsible for this conversion.

These factors act as a brake on your entire thyroid system. 

They slow down the amount of T3 that your body is able to produce and may make less efficient the medication that you are taking.  

If you can address and reverse these issues then you can “release” the brake on your thyroid and finally start feeling better! 

I’ve created a list of the most common factors that blunt this conversion process below: 

  • Dieting & Calorie restriction (slows down your metabolism) – Calorie restriction, as little as 1,500 calories per day for 3 weeks, is enough to blunt thyroid function and reduce T4 to T3 conversion (2). This might be the #1 problem for many thyroid patients who also tend to struggle with weight. They get trapped in a situation where they are overweight but try to diet to reduce the weight, only to further reduce thyroid function which leads to weight gain
  • Inflammation (from any cause) (3) – Inflammation is really nonspecific but inflammation from any cause (if systemic) can damage thyroid function. You can identify inflammation by looking for markers such as CRP and ESR. If elevated, these markers may be an early sign of inflammation. 
  • Lack of sleep (4) – If you are sleeping less than 8 hours per night then you may be reducing your thyroid function without realizing it
  • Intestinal issues (Dysbiosis, IBS/IBD, etc.) – A large portion of thyroid conversion actually happens in the GI tract or gut (5). If you have problems in the gut then this may limit your ability to convert T4 to T3. Problems such as intestinal dysbiosis (changes in gut bacteria), inflammatory conditions such as SIBO/SIFO/IBD, and other issues can all cause issues. Treating gut-related issues should be a priority if you have thyroid disease. 
  • Stress (emotional, physical, etc.) – Stress, from any cause, will limit thyroid function and block thyroid conversion (6).
  • Chronic and acute infections – Acute infections such as pneumonia can cause issues but also more chronic infections such as viral or bacterial overgrowth syndromes can also cause issues. 
  • Medications – It is well known that certain prescription medications can block thyroid function (7). Included on this list are blood pressure medications, diabetic medications, seizure medications, iodine, PTU/Methimazole, steroids, and heart medications like amiodarone. It may not be possible for you to stop taking your medication but you should look for alternatives if possible. 
  • Endocrine-disrupting chemicals (those you come into contact with daily, some people are more sensitive than others) – Endocrine-disrupting chemicals are chemical compounds that humans come into contact with on a daily basis that look like real hormones but aren’t. These hormones can trick your body into thinking the real hormones are there and they may compete for binding on cellular receptors (8). EDCs are found in plastic bottles, receipts, foods, plastics, and many other items that you come into contact with daily. Limiting your exposure to these chemicals may help improve your thyroid function. 

If you have any of these issues going on in your body then your thyroid function may suffer. 

These conditions may lead to an increase in a metabolite known as reverse T3 (a topic for another time). 

Reverse T3 is the metabolite created when your body is having trouble with the thyroid conversion process. 

Therefore, it can be used as a marker of thyroid conversion in your body. 

You can test for reverse T3 with a simple blood test. 

Factors that INCREASE T4 to T3 Conversion (You can use these to improve how well your thyroid works)

So what are you supposed to do if you have any of the factors listed above?

This section will discuss some of the available therapies that you can use to potentially help improve T4 to T3 conversion. 

  • Fixing the problems listed above (you must know what is causing the issue!) – The first, and most important, option is to try and find the root cause of your issue and address that problem. This may require a physician to help but in many cases, it will not. For instance: if you know you are struggling with calorie restriction then the first step is to stop that behavior! If you have known gastrointestinal issues then you can address that problem with basic therapies such as probiotics or enzymes. If you are struggling with stress then adding yoga or meditation to your daily regimen can help. If you are having issues with sleep then you can focus on ways to improve that and so on. Some issues, such as the use of medications, may require that you find a physician to help (and even then you may not be able to adjust your medications). In many situations, you may find that you have a number of factors that are limiting your T4 to T3 conversion. Each of these factors may contribute 5-10% so you may have to address many issues to see noticeable improvement. 
  • The use of certain supplements – Another strategy to improve T4 to T3 conversion is to use certain supplements. Supplements such as zinc, selenium (9), and guggul may all help your body naturally improve this process. The use of minerals such as zinc and selenium will only help if you are deficient, but many people around the world most likely are due to poor widespread dietary patterns. I’ve included the most effective mix of nutrients and vitamins in my T3 conversion booster which has helped many people improve thyroid function. You can learn more about that supplement here
  • Exercise (the right amount for your body) – Exercise is one of the easiest ways to increase both T4 and T3. A moderate amount of exercise can improve thyroid hormone production from your thyroid gland while simultaneously increasing thyroid hormone levels. The only catch here is that you must be exercising enough while avoiding overexercising. Overexercising can actually cause the opposite effect and lead to decreased levels of both T4 and T3. Learn how much is enough in this guide
  • Diet – While your diet doesn’t directly influence thyroid conversion it can absolutely indirectly affect thyroid conversion. Consuming unhealthy foods can lead to things like low-grade inflammation and gut problems. Both of these variables can negatively impact thyroid conversion. Learn which foods to avoid and which foods you should be eating to promote healthy thyroid function in this guide
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Using these strategies can help you increase thyroid function naturally and may even help if you are taking medication. 

Remember:

If you are taking thyroid medication your body still must convert T4 into T3. 

So all of these factors still matter if you are taking thyroid medication or if you don’t have a thyroid at all. 

The good news is that almost everyone with thyroid-related issues can benefit from this information. 

Bypassing T4 to T3 Conversion with T3 Medication

Another strategy that we will discuss (briefly) is the use of T3 thyroid hormone to bypass T4 to T3 conversion. 

We already discussed the importance of T3 and how it does pretty much all of the heavy lifting when it comes to thyroid function in your body. 

Normally, thyroid medications that contain T4 must be activated to T3 before your body can really use them

But you can skip out on this process by using T3 medications such as liothyronine or Cytomel

If you ingest T3 medications then they do NOT require activation in the way that T4 medications do. 

This allows you to bypass the conversion process and start feeling better almost immediately. 

This doesn’t mean that you should skip out on all of the therapies listed above, but instead, combine them all together for maximum benefit. 

I find that using medications that contain T4 + T3, using supplements designed to improve thyroid conversion, and addressing issues that blunt thyroid function all at the same time cause the best results clinically. 

You can learn more about using T3 medications here

Conclusion

The bottom line?

Addressing this tiny concept known as thyroid conversion may be one of the most important things that you learn about your thyroid. 

Most of the time, patients feel helpless with their thyroid because so much depends on their doctor and what he/she is willing to do. 

But if you understand your thyroid you can take steps to optimize whatever thyroid function your body is capable of producing

Just remember:

This is a process and it takes time!

Don’t expect immediate results, but instead, give your body weeks to months to improve. 

Now I want to hear from you:

Are you struggling with T4 to T3 conversion? 

Have you tried therapies designed to improve this process?

Have they worked for you? Why or why not?

Have you tried T3 medications?

Leave your comments and questions below! 

Scientific References

#1. https://www.ncbi.nlm.nih.gov/pubmed/6479377

#2. https://www.ncbi.nlm.nih.gov/pubmed/1249190

#3. https://www.ncbi.nlm.nih.gov/pubmed/27051079

#4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2910542/

#5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1411539/

#6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3148770/

#7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1070767/

#8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5751186/

#9. https://www.ncbi.nlm.nih.gov/pubmed/25758370

how to increase T4 to T3 conversion
T4 basics: the test, the medication, the hormone

T4 Thyroid Basics: The Test, The Medication, The Hormone

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This is video #3 in my thyroid beginner series and today it’s all about T4. 

T4 is essential in understanding your thyroid because it’s actually 3 different things in one. 

T4 is a prescription medication, a hormone that your body produces naturally, and a test that you can order. 

Learn the differences, what they mean and how they can help you manage your thyroid: 

What is T4?

T4 is the most abundant thyroid hormone that your body produces naturally (assuming it’s working properly). 

It’s also known as Thyroxine which is the “official” or scientific name. 

If you hear someone refer to thyroxine just realize that they are referring to T4 and vice versa. 

So what’s the big deal with T4?

T4 is important in understanding your thyroid because it’s involved in the thyroid feedback system. 

T4 thyroid hormone molecular structure

T4 is produced by the thyroid gland after the gland is stimulated by TSH from the pituitary

T4 then circulates through the body where it is converted (on demand) by your cells into the active T3 thyroid hormone. 

If you have low circulating T4 then you will have low circulating T3 and this will cause the symptoms of hypothyroidism!

Let’s dive into the various definitions of T4 and how understanding what they mean can help you as a patient…

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The Complete List of Thyroid Lab tests:

The list includes optimal ranges, normal ranges, and the complete list of tests you need to diagnose and manage thyroid disease correctly!

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T4 the Hormone

As I mentioned previously, T4 is the most abundant thyroid hormone in your body. 

Your thyroid produces two major thyroid hormones: T4 and T3

About 80% of the thyroid hormone that your thyroid produces is T4 or Thyroxine. (1)

This leaves around 20% left as T3 (the primary active thyroid hormone). (2)

But why does your body produces so much T4 relative to T3?

The reason is most likely related to the control of the thyroid system. 

For instance:

T4, by itself, is not an active thyroid hormone. (3)

It must be activated, by enzymes, into the active T3 thyroid hormone. (4)

So your thyroid spits out some amount of constant T3 (directly from the thyroid gland) and then converts the rest of T3 that it needs from the abundance of T4 in the bloodstream. 

This way it can control how much thyroid hormone your cells need based on the demands that YOU put on your body. 

I think it’s most helpful to consider the analogy of a dam. 

In this analogy the dam is thyroid conversion (T4 to T3 conversion), T4 is the water behind the dam, and T3 is the water that is allowed through the dam

By setting up this system your body can titrate and carefully control thyroid function. 

And this makes sense, considering how important your thyroid is to your entire body! 

T4 the Test

But what about T4 as a test?

It should come as no surprise that we can test the amount of T4 that your body produces naturally (or the amount that you take by medication) through the blood. 

Doctors can do this by ordering what is known as a “free T4” test. 

High free T4 and low TSH in hashimoto's

This test is incredibly important in understanding how your thyroid is functioning because it is THE primary hormone that your gland produces. 

In many cases, I believe that the T4 (and T3) hold more value than the TSH when evaluating thyroid function. 

You can read more about how and why TSH can fall short as a predictor of thyroid function in thyroid beginner series #2 here

But what does T4 tell you when you measure it?

Several very important things:

#1. It gives you an idea as to how your thyroid gland is functioning. 

Your thyroid gland is stimulated by the pro-hormone TSH. 

This hormone tells your thyroid gland to produce both T4 and T3. 

If you test for T4 and find that it is low then it can tell you how responsive your thyroid gland is to TSH. 

The normal hypothyroid lab pattern is usually a high TSH accompanied by a low free T4

And this makes sense if you think about it:

If your thyroid can’t produce T4 then it responds by increasing the amount of TSH to try and overstimulate the gland to produce more hormone. 

But if your thyroid can’t produce thyroid hormone because it is damaged then the TSH will remain raised and your T4 will remain low. 

This is the “standard” pattern that most patients who have hypothyroidism or Hashimoto’s present with. 

#2. It gives you an idea as to how well your body is converting T4 into T3. 

We’ve already discussed how important T3 is for thyroid function in your body. 

And testing for Free T4 can help you identify issues with this conversion process. 

How does it help?

You can test both Free T4 and Free T3 and look at the ratio between the two of these hormones. 

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Your T4 should be in a “healthy” range (usually the top 50% of the reference range) and your T3 should be in about the same range. 

If you have issues with T4 to T3 conversion you may see your T4 increase while your T3 decrease. 

In cases where your body isn’t able to produce thyroid hormone, you may see both the T4 and the T3 low. 

But both situations may be a clue that your body isn’t converting as well as it should. 

#3. It gives you an idea if you are absorbing or utilizing thyroid medication that you are taking by mouth. 

T4 can, and should, be tested when you are taking thyroid medication by mouth. 

It goes without saying, but in order for your body to actually “use” thyroid hormone that you take by mouth, it must be absorbed by your body. 

There are several factors, including the time of day that you take thyroid medication, (5) that can impact the rate at which you absorb thyroid medication. 

You can easily determine if you are absorbing thyroid medication by checking Free T4 before you start medication and 8 weeks afterward. 

You should see your Free T4 increase as you take thyroid medication and you should see your TSH drop. 

If these things don’t happen then you may need to consider that you are not adequately absorbing your medication. 

Other factors such as supplements, calcium, (6) and food intake can all impact how well you absorb thyroid medication (and this is why it’s generally recommended that you take thyroid hormone on an empty stomach). 

You can learn other tips and tricks to help maximize thyroid hormone absorption here

T4 the Medication

T4 is also the most commonly used thyroid medication. 

Prescription thyroid medications, especially those used by conventional doctors, contain T4 thyroid hormone. 

Medications that fit into this list include Synthroid, levothyroxine, Tirosint, and Levoxyl. 

These medications contain ONLY T4 or Thyroxine and should be compared to other medications which contain either combinations of T4 and T3 or just T3 alone. 

T4 has become the most commonly used thyroid medication over the last 30 years or so (7) because it is felt to be the most “consistent” thyroid medication and because it has the longest half-life (which means it stays in your bloodstream the longest). 

But it should always be remembered that your body naturally produces both T4 and T3 and that replacing only T4 may be part of the reason that so many patients remain symptomatic despite taking thyroid medication. 

Doctors only use T4 because they assume that your body will have no issue in converting T4 into T3. 

But this logic doesn’t take into account that each person converts T4 into T3 at a different rate and that we aren’t all equal in that regard. 

The problem with T4-only medications is that newer studies have shown that many people who use T4 have a lower than normal T3 (8) (the active thyroid hormone) even though they have a normal TSH. 

This approach to thyroid hormone replacement may be part of the reason that so many patients remain symptomatic despite having a “normal TSH”. 

It should also be noted that you can safely use T3/T4 thyroid medications without negative side effects provided they are used appropriately. 

Conclusion

That concludes our discussion on T4 basics!

Just remember that while T4 is an important thyroid hormone for your body, it is not as powerful as T3 thyroid hormone. 

But it still has value in terms of testing and using T4-only thyroid medication. 

Some people are able to use T4 thyroid medication and feel great while others may need some T3 to feel optimal. 

If you have thyroid problems make sure that you can differentiate between T4 the test, T4 the hormone, and T4 the medication

Now I want to hear from you:

Have you had your T4 tested? Was it low or normal?

Are you taking T4 medication? Is it working for you?

Why or why not?

Leave your comments below! 

#1. https://www.ncbi.nlm.nih.gov/pubmed/12915350

#2. https://www.ncbi.nlm.nih.gov/pubmed/12915350

#3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699302/

#4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3673746/

#5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4650787/

#6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3092723/

#7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4980994/

#8. https://www.thieme-connect.de/DOI/DOI?10.1055/s-0043-125064

what you need to know about t4 thyroid hormone
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Up to 50% of American women who get pregnant gain more weight than is recommended by medical professionals (1). This wouldn’t necessarily be a problem if weight loss after pregnancy was easy, but that isn’t the case.  With this crazy high incidence of weight gain, it’s no wonder that women search for weight loss programs …

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Triiodothyronine (T3) Hormone Guide: Why It’s So Important

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Learn everything you need to know about the thyroid hormone Triiodothyronine including how it functions in your body, how it is produced, the symptoms associated with deficiency, and how to improve (both naturally and through medication) and optimize your levels in this post:  What is Triiodothyronine? Triiodothyronine is the complete name given to the most …

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Complete T4 and T3 Guide: What Do They Mean for your Thyroid?

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5 Benefits of using T3 Medication

Many patients on levothyroxine or Synthroid stand to benefit by simply adding a small amount of T3 medication to their regimen.  T3 is metabolized in the body in a different way than T4 which makes it special. It’s also the strongest and most powerful of all the thyroid medications but it must be used correctly. …

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