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Low T3 Explained. What You Should Know About this Thyroid Hormone

Getting Your T3 and Free T3 Thyroid Hormone levels Checked

Triiodothyronine, or T3, is a hormone that the thyroid gland produces. A T3 blood test can help a doctor diagnose thyroid conditions. While this test is ofter overlooked, in the future more and more doctor will be testing for low T3 levels and trying to understand the cause of Low T3.  While most doctor simply make a diagnosis of hyperthyroidism or hypothyroidism based on a TSH test and sometimes a Free T4 this is not always the best management of a patient. In this article, I will explain why testing Free T3 and Total T3 levels are so important. As a person who has thyroid disease or who suspects thyroid disease, you might be familiar with the thyroid hormones like TSH, T4 and free T4, but there are a few other Thyroid hormone markers that should be tested if you have a normal TSH but still suffer with low thyroid symptoms.

Low T3 Symptoms- Who needs Testing?

Sometimes patients have a normal TSH and normal T4 levels and still suffer with the thyroid symptoms you see listed below. If the is the case, we recommend getting your total T3  and free T3 levels tested.

  • sweating
  • tremors
  • sensitivity to heat or cold
  • Fatigue
  • irritability
  • mood swings
  • unexplained weight loss
  • difficulty sleeping
  • bulging or irritated eyes
  • hair loss
  • irregular or slower heartbeat
  • shortness of breath
  • high blood sugar
  • increased frequency of urination

Quick Overview of your Thyroid Hormones

  • TSH: TSH is released from the pituitary gland in the brain, and it stimulates the thyroid gland to make thyroid hormones.
  • T3 and T4: The thyroid gland makes and releases T4, as well as some T3. Total T3 and T4 levels include T3 and T4 that is bound to protein, as well as T3 and T4 that is not, known as free T3 and T4.
  • T4 conversion to T3 and rT3: After its release from the thyroid gland, T4 is converted to T3, which is an active thyroid hormone, or to rT3, which is considered an inactive form. The rate and ratio of T4 conversion to either T3 or rT3 depend on the body’s metabolic needs.
  • If you have a normal TSH and still suffer with low Thyroid symptoms you need to become familiar with some of the overlooked thyroid patterns that don’t follow the text book.

Low T3 Explained. What You Should Know About this Thyroid Hormone

Common Causes of Low T3 Thyroid Hormone

Hypothyroidism is a common cause of fatigue, anxiety, depression, brain fog, hair loss, weight gain. But what many doctors fail to evaluate are the levels of Reverse T3. High Reverse T3 will cause many low Thyroid symptoms. Dr Hagmeyer here and today we are talking about Low T3, or T3 syndrome or Poor T4 to T3 conversion- you may see many different names given but ultimately this low T3 is a common reason why you suffer with fatigue, depression, weight gain, brain fog, hair loss, bloating, acid reflux and many other symptoms that are associated with low thyroid. Todays video you will learn

  • Reasons why you are a poor T4 to T3 converter and have Low T3 and
  • My favorite tests that can help us understand T4 to T3 conversion.

You will remember that T4 is the inactive thyroid hormone and T3 is the active thyroid hormone. When you take Synthroid, Levothroxine you are taking T4.

Some of you watching this video might be thinking, If I am low in T3, can’t I just take a T3 replacement hormone or a combination of T4 and T3? While this makes sense on the surface, this approach still fails to address the reason for why you have low T3 in the first place.  You can learn how to calculate your T3/rT3 ratio and understand why this ratio is so important here

Gut Disbiosis Is One of The Causes of Low T3

Low T3 is caused by poor conversion of T4 into T3. There are several reasons for this but one of the big causes that we will address in today’s video is the connection between your gastrointestinal microflora and your T3 levels.

These days, doctors are so concerned with tinkering around with thyroid hormone replacement T4, T3, Combo T4/T3, Armour, Cytomel Tirosint) that they have forgotten to ask the question why are the thyroid levels low in the first place. Where is the “Low” coming from, “How” did it get low. This is most logical question that should be asked and investigated.

Forget about the medication for a moment and look at the big picture. There are 3 reasons you need to understand the information in today’s video.

Low T3 or low Free T3 is a Sign that you have a problem with T4 to T3 Conversion.

if you can identify with any of the three statements below, its time to get your T3 and Free T3 levels tested.

#1 Taking Thyroid medication for the last 6 months, 12 months, or longer and still feels lousy,
#2 Taking thyroid medication, felt good for about 6 or 12 months and now you feel like you did prior to taking thyroid medications. All those symptoms have slowly and steadily returned.
#3 and finally this video is for those of you who already been told that you don’t convert T4 into T3 very well- (these are woman who have blood sugar issues, problems with estrogen, testosterone and GI issues such as leaky gut, SIBO or IBS)-

T4 to T3 Conversion is A common Problem.

Poor T4 to T3 conversion of Low T3 is a very common problem, next to having autoimmune thyroid disease aka Hashimotos this is probably the 2nd most common pattern that I see in my office daily. So it is definitely worth talking about. And I see this everyday with my Thyroid patients. One of the keys to today’s video is making sure you get your T3 levels measured as well as your Free T3 levels. So if you haven’t had that done, make sure the next time you get your blood drawn you have your doctor or endocrinologist run T3, Rt3 and Free T3. If they wont run this testing for you, you can order a complete Thyroid panel and consult here.

(By having your T3, Free T3 levels tested and Your Reverse T3 levels you will also be able to figure out your T3/RT3 ratio. Which many researchers feel is a better marker for Thyroid function than TSH. If you want to know more about Reverse T3 levels, you can watch the video below.



Why You Want to Calculate Your T3 Reverse T3 ratio

  • This ratio helps you understand how well your body is converting T4 into T3 – read more about this here if you haven’t heard about this conversion process.
  • It helps you understand if your current medication and dose are working for you – If your medication is working then your free T3 should be normal and your reverse T3 should be low/normal. If your levels are not improving with thyroid medication here are 10 reasons why you thyroid medication stopped working.
  • It helps put your symptoms into context – Many people find that they are confused because of their so-called ‘normal’ lab tests and this T3: reverse T3 ratio can explain how you can have a normal TSH but still suffer with low Thyroid symptoms. If your Reverse T3 is elevated you will need to further testing to uncover why you have high reverse T3 levels.
  • It can help you understand other factors which need consideration – Do you have symptoms of inflammation? do you have a leaky gut or SIBO or other GI problems? Some of the factors such as gut health and inflammation can all influence this ratio. If your ratio is off then it can help direct you to other problems which may be influencing your thyroid.
  • It’s one of the most sensitive measures of thyroid function – the difference between your free T3 and your reverse T3 can identify thyroid dysfunction very early on and becomes abnormal long before other measures of thyroid function such as TSH and free T4.

Optimal T3 and Free T3 Thyroid Hormone Level Ranges

Don’t look at the ranges that come with your blood work- those are not FUNCTIONAL Thyroid lab ranges. We want to look at the functional lab range.  The functional lab range for Total T3 levels is between 100-180. I personally like to see this levels in the range of 140-160. The functional lab range for Free T3 should fall between 3 and 4.

So that should give you some reference ranges to shoot for when you get your T3 and Free T3 levels checked. But Remember what I said at the beginning, our Goal is to uncover why we are not converting T4 into T3.

Low T3, Free T3 Thyroid Hormone Levels And Your Gut

The health of your gut is one of the most critical systems to properly evaluate when you have hypothyroidism, Hashimoto’s or if you have low T3. The gut can interfere with thyroid function in many ways- the most obvious one is nutrient absorption. This can become a vicious cycle. Poor gut function causes poor thyroid function and poor thyroid function causes Low HCL production and when you have low HCL production you cant absorb things like (calcium, Iron, Zn, copper, B vitamins, Vitamin D) anybody out there with low Vitamin D?

Probably most of you watching this have or have had low vitamin D prior to supplementation. Anybody out there with acid reflux or bloating? sure you do…. this is the result of low levels of HCL production and not that I want to gloss over these other symptoms, but what I really want to talk to you about today is the importance of the GUT microflora. When that gut flora becomes unbalanced we often see problems like bloating, IBS, Yeast overgrowth, inflammation, and low levels of pancreatic enzymes which can impact fat soluble vitamins A,D,E,K.

We often see parasites, yeast, bacterial overgrowth (SIBO) and because of that… you can lose up to 20% of thyroid hormone conversation.  If you are like most people with low T3, you cant afford to lose another 20% of your thyroid hormone output.

Low T3 Explained. What You Should Know About this Thyroid Hormone 1

The Technical Explanation of Why You Develop Low T3 Thyroid Hormone Levels

For those of you who want the specifics who what where and why… Here is what happens- (we are going to get technical for just a brief moment so stay with me.)

Once your thyroid is stimulated by TSH it makes T4 and about 20% of that T4 is converted to T3 in the GI tract in the forms of T3 sulfate (T3S) and triiodothyroacetic acid (T3AC) and a small portion of it gets converted to Reverse T3. The conversion of T3S and T3AC into active T3 requires an enzyme called intestinal sulfatase. (very important)—This enzyme is made by the happy and more importantly HEALTHY gut bacteria.

Low T3 Dr Hagmeyer

If you have low levels of these good bacteria (because your gut has been bombarded with antibiotics, acid reflux pills, birth control pills, bad diet, SIBO, Leaky Gut, and all those things we talked about in my video tilted, “Causes of Intestinal Disbiosis and Leaky Gut” than you don’t produce sufficient amounts of Intestinal Sulfatase and when you don’t produce intestinal sufatase—you have less than optimum T4 to T3 conversion.

Understand the Gut And You Will Understand A Big Piece of Thyroid Function

Here is what I like to see in gut testing when it comes to the  Thyroid

  • It should be a DNA amplification.
  • It should include Predominant anaerobes the kinds of anerobes and quantity of good bacteria,
  • Secretory IgA– this is an immunoglobulin- this is your first line of the immune system defense (this indicates mucosal barrier integrity)- these levels are often low when you body has been loosing a fight against an infection and elevated when fighting a current infection.
  • Long and Short chain fatty acids,
  • Pancreatic elastase– marker for enzymes that assist is the breakdown of fats.
  • Parasite and egg testing- Cryptosporidium, Giardia, E.histolytica, next Calprotectin- this is one of the Inflammatory markers that distinguishes non inflammatory bowel disease from inflammatory bowel disease.
  • Yeast and Fungal overgrowth,
  • Fecal cholesterol levels
  • Beta Glucoronidase

These Gut and GI markers are a fantastic window into the functional health of your GI tract. A test like this will shed so much light on the connection between your thyroid and your gut.

I hope this video serves you well. If you have questions or you want to get in touch with my office the best way to do that is visit my website and submit a contact us form.

Until next time- Keep digging into those layers and don’t give up! You can get better! So there you have it!If You want to address one of the pieces behind Low T3 or Poor T4 to T3 conversion, one of the things you need to do is focus on your gut.

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