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Thyroid Health – Understanding Reverse T3

Thyroid Hormones - Reverse T3

The thyroid is a critical element in one’s overall health. This is because the hormones secreted by the small butterfly-shaped gland interact with every cell in the body and influence their function. A malfunctioning thyroid can lead one to experience significant health issues or develop thyroid-related disease such as hypothyroidism and hyperthyroidism. Being better informed on what Reverse T3 is, what it does, and the great value that comes from including it in thyroid blood testing can help one support optimal thyroid function.

Intro to Thyroid Hormones

The two most prominent hormones produced by the thyroid are thyroxine (T4) and triiodothyronine (T3). But there are others involved in maintaining a healthy thyroid and ultimately a healthy body. One such hormone that is wrongly invalidated by many endocrinologists is reverse triiodothyronine (Reverse T3). Because of inadequate appreciation or understanding of the impact Reverse T3 has on the body, many have been left to unduly suffer from a thyroid imbalance.

There are several hormones secreted by the thyroid. The three most important hormones regarding thyroid disease and cellular function are:

  • T4, known as the storage or inactive form of thyroid hormone, is the hormone most produced by the thyroid.
  • T3, called the active form of thyroid hormone, is five times more active than T4.
  • Reverse T3, the inactive mirrored form of T3, inhibits T3 function.

Before the body can fully utilize thyroid hormone, it must be converted from T4 into the active form T3. T4 is capable of being converted into either T3 or Reverse T3 depending on the removal of specific iodine atoms. By removing a certain iodine atom, T4 is converted into T3. Alternatively, if a different iodine atom is removed, the result is Reverse T3. This process of T4 conversion is known as monodeiodination.

In a properly functioning thyroid, roughly 40% of T4 is changed to T3 and about 20% is translated into Reverse T3 daily. However, if one’s thyroid is malfunctioning, or if the body needs to conserve energy and is under significant stress, the conversion ratio may change to 50% of T4 becoming Reverse T3. A significant change such as this greatly impacts thyroid function and hormone availability.

A Closer Look at Reverse T3

Reverse T3 is the mirrored inactive form of T3 and is instrumental in keeping thyroid hormone levels in balance. Without the presence of Reverse T3 in one’s system there is great risk that their T3 levels reach dangerously high levels resulting in a severe case of hyperthyroidism (an overactive thyroid frequently caused by excess T3). Alternatively, too much Reverse T3 overly inhibits T3’s ability to provide energy and oxygen to one’s cells resulting in reduced metabolic function on a cellular level. Reverse T3 and T3 compete for the same receptors throughout the body. If there is a greater prevalence of Reverse T3 in one’s system, it will effectively block active thyroid hormone from reaching cells. Maintaining the appropriate ratio of T3 to Reverse T3 helps keep the body running smoothly.

As an effective T3 inhibitor, Reverse T3 helps the body maintain a proper balance of active thyroid. Not only does it block receptor sites but it influences conversion of T4 into other hormones. Studies have found that Reverse T3 can be 100 times more effective at reducing the conversion of T4 into T3 than Propylthiouracil (PTU), a treatment option for those with hyperthyroidism. Although this regulatory action is useful for maintaining proper thyroid hormone levels, if Reverse T3 is overproduced it can cause severe hypothyroidism. Those who have hypothyroidism generally see an increase in symptom severity when there is an overabundance of Reverse T3 in their bloodstream.

Contributors of Hormone Imbalance

Thyroidal dysfunction is not the only possible cause of increased Reverse T3. Stress-related hormones can further compound a Reverse T3 imbalance. When there is an excess of Reverse T3 in one’s system their metabolism slows leaving them feeling sluggish and tired. To counteract this, the body releases cortisol, also known as the stress hormone, to increase alertness and energy. Although this temporary mental boost has many uses, especially when one is in physical danger, if it is relied on as a primary source of energy various problems develop. Regular release of cortisol, due to chronic stress, T3 deficit, or excess Reverse T3, can exhaust the adrenals, causing one to experience long-lasting fatigue. Furthermore, cortisol inhibits T4 to T3 conversion, resulting in increased prevalence of Reverse T3 in one’s system.

Other conditions that contribute to increased Reverse T3 levels include:

  • Chronic fatigue
  • Acute illness and injury
  • Chronic disease
  • Increased cortisol (stress)
  • Low cortisol (adrenal fatigue)
  • Low iron
  • Lyme disease
  • Chronic inflammation

Poor Testing Practices

Unfortunately, a large portion of the medical community still believes that Reverse T3 is an unimportant factor in one’s thyroid function. This has caused most practitioners to rely on thyroid stimulating hormone (TSH) and T4 testing alone to analyze one’s thyroid function. These tests do not account for conversion issues or recognize if there is an overabundance of Reverse T3 in one’s system. Even if T4 and TSH levels fall within the “normal” range, one may still experience health issues if there is excess Reverse T3.

According to a study in The Journal of Clinical Endocrinology & Metabolism, TSH and T4 levels are poor indicators of one’s thyroid function. It was further stated that the use of these tests alone do not reflect an appropriate image of thyroid health for a significant percentage of patients. Relying solely on tests that neglect Reverse T3 can leave patients suffering from undiagnosed thyroid dysfunction for years. Thankfully a growing number of holistic and integrative medical practitioners, particularly those who specialize in hormone balance, are vocalizing the importance of Reverse T3 testing for diagnosis and treatment.

Using All the Pieces

Because Reverse T3 is such a critical element for thyroid function, it is important to have appropriate testing. If you are experiencing hypothyroid symptoms while your thyroid blood panel tests present normal TSH and T4 levels, it is important that you get your Reverse T3 levels tested as well. Without having a clear picture of the numerous elements impacting thyroid function it is near impossible to properly diagnose and treat one’s unique condition. If you have thyroidal concerns, make sure Reverse T3 is included in your thyroid blood test panel.

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Mary Vale
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Mary Vale

I have both type 1 diabetes and hypothyroidism. I am being treated with levothyroxine and insulin. However the thyroid tests are coming back with the T3 levels at .006 … they are cutting my levothyroxine, but I have all of the symptoms of hypothyroidism… I weigh over 200 lbs now, with my normal weight being 150 lbs. …. and am cold especially my feet and legs… I am tired, my tongue is swollen and I cannot function like I used to due to brain fog. My skin is dry and itchy but it could be the diabetes too. I have… Read more »

Naomi Parker
Admin

Hello Mary,
Levothyroxine is a T4-only medication. If you are on it and are still experiencing extremely low T3 levels, you and your doctor should consider either a combination (T4/T3) or straight T3 medication. You are probably experiencing what’s going on in this article: your T4 is likely converting mainly to RT3 which is the exact opposite of T3.

I hope this information helps!

– Naomi

Linda
Guest
Linda

I have similar problems. I have done the best on Liothyronine, T3. My Rt3 levels were extremely high. We have also started treating my adrenals and I am doing much better. I take DHEA, Adrenal Cortex, and my T3. I am hoping that if my adrenals improve I can go back on Armour. I also take C and Astaxanthin to fight inflammation. Have your Dr. check your Rt3 level and if it is high ask for a T3 med. I go to a Naturopathic Dr I suggest you find a Naturopathic Dr as he will treat the whole body and… Read more »

Giselle
Guest
Giselle

Hi Linda

What is the name and city, state of your doctor?
Thanks!

Josiah
Guest
Josiah

See a doctor that will test TSH, free T3, and reverse T3. Also test saliva cortisol levels to see if you have adrenal burnout.

Debbie Stevens
Guest
Debbie Stevens

What is normal reverse T3 levels? Thanks.

Naomi Parker
Admin

Hello Debbie,
Here is a good calculator to determine if your RT3 is in a good range. The RT3 always needs to be looked at in conjunction with your T3 levels. https://stopthethyroidmadness.com/rt3-ratio/

I hope the information helps!

– Naomi

Teri
Guest
Teri

Rt3 < 15
Ideally 11 or lower

K87
Guest
K87

I was wanting to get someone else’s opinion and was wondering if you could help? My doctor said my reverse T3 is a little high in comparison to my free t3 level. Technically it still in the lab results reference range. She initially said all my thyroid levels was all normal but then I called back bc I’m in my first trimester of pregnancy and I know tsh should be under 2.5 and mine is 4.3. She said to talk to my endo about my rt3/freet3. So when I called back I told her I don’t have an endo so… Read more »

Naomi Parker
Admin

Hello,
Your doctor did the right thing! High RT3 does NOT mean you’re getting too much T3, especially when you have lab results to back this up. What is likely happening is you’re converting more of your T4 to RT3 rather than T3. Additionally, 5mcg is an extremely small dose and will not likely have a great impact.

I hope this information helps!

– Naomi

Holly Hanson
Guest
Holly Hanson

My reverse t3 is 30 the standard is 10 -24ng is mine considered high what should be done. My primary Dr. Thinks is normal

Naomi Parker
Admin

Hello Holly,
You’re right to think that the RT3 is not “normal”. Here is a ratio calculator to determine your RT3 range: https://stopthethyroidmadness.com/rt3-ratio/. It is highly likely that your T4 is converting more to RT3 than T3. Without getting into your treatment protocol, if you’re currently undergoing a T4-only treatment, it may be a good idea to discuss a combo (T4/T3) or T3-only treatment.

I hope this information helps!

– Naomi

Crystal
Guest
Crystal

Hi there, Just want to say THANK YOU so much for this informative article. I am almost 4 months post Thyroidectomy and very uninformed between my family doctor, Endo and ENT Surgeon. I’ve even had my family doctor tell me theres no such thing as Reverse T3. I start seeing a new Specialist next month and hope he will treat me based on what I ask, to which I plan to as for more thorough testing. I unfortunately think I am a prime candidate for my body to convert my T4 to RT3 due to high stress. Would a Thyroidectomy… Read more »

Teri
Guest
Teri

Crystal, many of us post TT found the previous T4 meds were not working like that did prior ndt or adding straight T3 makes all the difference !

Katie
Guest
Katie

This is so interesting. If I am with a HMO and my Dr refuses to test my Reverse T3, what are my options?

Teri
Guest
Teri

Katie, you can order your own labs without your dr using the online lab companies.. usually done at Lab Corp or Quest/Solstas ☺

Katie
Guest
Katie

This is an interesting topic. I have had all tests but Reverse T3 done. If my HMOdoctor refuses to run this test, what are my options? Also, could having chronic pain for 10 years co tribute to imbalance?

Heather
Guest
Heather

I have a heck of a time finding an ending to take me seriously. Despite my symptoms I was told “I look fine” by two different doctors including an endo. My pats recent tests were as follows:
TSH: 2.76 (within range)
Free T3: 4.72 pg/ml (high)
ReversT3: 43.3 ng/dl (high)
TotalT3: .165 ng/dl (high)
FreeT4: .72 ng/dl (.71 is low)

Multiple tests have comfirmed these numbers over the last 3 months. It’s like my t3 is saying Hyper but my TSH, ft4 and reverse say hypo. I have hypo symptoms. No one is willing to treat. I’m at a loss for a next step.

Naomi Parker
Admin

Hello Heather,
Have you had your thyroid antibodies checked?

– Naomi

CinColo
Guest
CinColo

Heather, what medication are you taking? The typical treatment for high Reverse T3 is to lower your NDT dose by as much as half or to lower your T4 only medication, and then add T3 separately. You also have to treat the cause of the high Reverse T3 (low iron/poor adrenal function being the most common causes) at the same time. In your case, you may also be pooling T3. I’m going through this now with the high reverse T3 (I have Hashimoto’s). My original doctor didn’t know how to treat high Reverse T3, despite my telling her how it’s… Read more »

Joelle
Guest
Joelle

what does it mean to have below normal low levels of reverse t3 and t7? all other levels look “normal” and I am on wp thyroid currently. the low reverse t3 level was low before I even started medication though

Marcia Thompson
Guest
Marcia Thompson

I have a lot of the symptoms of hypothyroidism(constipation, bloating, insomnia, dry skin, mental fog, easy weight gain etc). I had Graves disease about 22 years ago and was treated using PTU. I went into remission and I haven’t taken anything since for my thyroid. I have been on steroids (presently 5mg/day but for some 25 years or so at some level) from treatment for RA and myasthenia gravis and never being able to wean completely off and adrenal insufficient when checked (without my prednisone). I just had my GP run a thyroid panel and the numbers have come back… Read more »

sherri rapp
Guest
sherri rapp

Hello, I could really use your advice. No one in the Ocala Florida area seems to have any knowledge about Reverse T3. Here are my results. Please help! I’m Generic Synthroid taking 50 mg daily. That is it….I feel like crap! My heartbeats in my back, I have borderline anxiety attacks and so so tired. I have lost interest in everything I love! I’m just too tired. If T3/T4 is recommended….what brand to you suggest? I have read bad things about Armour and bad things about the other natural brands. Sigh…I’m lost and frustrated. FT4- 1.37 ng/dL FT3- 2.9 pg/ml… Read more »

lisa ondris
Guest
lisa ondris

in november my doctor doubled my t3 med and in January i got my first high reverse t3 results, really don’t know how to correct this, it was 32. don’t know if i got that high of a result because my t3 was doubled, or because i deal with a ton of stress and inflammation issues where do i go from here?

Bonnie meada
Guest
Bonnie meada

Hello, I have Hashimoto’s and was diagnosed about 7 years ago. I have taken several different thyroid medications over the years and am now on WP thyroid. I recently asked my endocrinologist to run my T3 and reverse T3 levels because he has only been running TSH and T4. He refused. I don’t have an explanation from him yet but I am angry. Why would he not want to run these tests? Is there some reason that he wouldn’t see them as valuable?

Jocelyn
Guest
Jocelyn

Hi there, I recently had a blood panel done at the TSH and T4 and T3 uptake came back in the normal range, however my Reverse T3 came back really high. My doctor told me she’s not concerned because my other numbers are normal but I’m not convinced. Is this due to stress? Thanks

Jess
Guest
Jess

I’VE BEEN LOOKING FOR SOMETHING LIKE THIS FOR MONTHS! all of my labs (tsh ft4 ft3) are all normal. But my rt3 is = the high end of the range, however my ratio of ft3 to rt3 is 14. I have ALL the textbook symptoms of hypothyroidism along with extremely high cortisol. My endo will only focus on cortisol and has yet to recommend how to improve cortisol he totally dismisses rt3 as an issue. I feel like hell every day and it’s getting worse. I know that a t3 med will likely help me feel better but I cannot… Read more »

Theresa
Guest

What would cause a high TSH with low T3, T4, and low reverse T3?

Kalpana C
Guest
Kalpana C

Hi, I was diagnosed with Hashimoto’s hypothyroid 2 years ago. However, been on thyroid supplement since 2012. I got tested last week for Free T4, TSH, and Reverse T3. For some reason, my Endo doc did not test Free T3. Free T4 is 1.45, TSH is 0.553 and reverse T3 is high at 31.3. Reverse T3 was also high in September last year where it was 24.6. I currently taking Synthroid (T4) med 75mcg. My Endo doc keeps asking me if I had a recent illness or something but does not change medication. So after reading this article and several… Read more »

Priscilla Endicott
Guest
Priscilla Endicott

I have been diagnosed with hypothyroidism, but the doctors I go to won’t do anything because TSh and T4 levels are normal. I have mentioned getting an RT3 just to have doctors tell me we don’t do that or just look at me like a space alien. My T3’s are barely in range at 24. Should I be worried about this?

Patti Wise
Guest
Patti Wise

Hi, My doctor did a thyroid panel and he said my levels were good except for my reverse t3 which is 30. I have in the past been treated for a high tsh , but I am not taking medication at all. I have a large nodule on the right side of my thyroid which was tested for cancer and a smaller nodule on my left. The larger on presses on my larynx which causes me to have a very raspy voice. I have a laundry list of hypothyroid symptoms, but the major symptoms are exhaustion, joint pain, muscle weakness,… Read more »

Elizabeth Johnson
Guest
Elizabeth Johnson

My reverse t3 was 19 and standard range was 0 to 35. I assumer mime is good. My tsh is 3.59 when 4.2 is highest and my free t3 and free t4 were in middle of Their standard ranges too.

JasonH
Guest
JasonH

In my opinion, and based on my experience, I believe you have hypothyroidism. The lab range for TSH 0.5-4.5 is incorrect. TSH should be <2. Do you have a TPO antibody test? I bet it will show some positive number confirming Hashimoto's for hypothyroidism. Do you have symptoms?

Jen
Guest
Jen

What has anyone tried to get rid of weight…

Sandie Gill
Guest
Sandie Gill

I have received my reverse T3 levels back and they are 522. My GP knew nothing about what this meant and I have blood tests showing inflammation as well as many nodules on thyroid. All other thyroid levels showing thyroid stimulating hormone 2.4, t4 – 12.49 low and t3 – 4.7. GP test all show within range. Don’t know what to do as I feel constantly unwell and exhausted. Having a another ultrasound on thyroid.

Kathi
Guest
Kathi

I think you need to go see an endocrinologist.
GP do not specialize in this.
My GP let me suffer for a year thinking my iron was low and just gave me iron pills.
You need a specialist

Shari
Guest
Shari

Would love to get your opinion on my recent labs. I have all the symptoms of hypothyroid except I’m loosing weight but I am wondering if it might actually be my pituitary. TSH 0.97, FT4 1.10, FT3 2.4, RT3 16.3. Back in January my provider said my numbers were low as well so she was retesting. I don’t have those numbers. Thanks Shari

Shari
Guest
Shari

Also my TGAB 0.9. Ferritin 77, Adiponectin 16. SHBG 167. I am on estradiol. I came across some labs from 2010 TSH 1.10, T3 0.98. I have all the symptoms since 2009. I also have Fibromyalgia. Should I be on T4 & T3 medication? Any other testing?

Kathi
Guest
Kathi

I would like to know if the reverse t3 is not normal but the t3 and t4 are within normal range, could that be the reason I cannot lose weight?
My doctor reduced my dosage to the lowest I’ve ever been on .137. And I have gained 10 lbs and no matter what diet I’m on,I can’t lose.
I’m so discouraged

mike stevens
Guest
mike stevens

I’d like your opinion on my lab results: Reverse T3: 24.4 ng / dL ; free T3: 2.36 pg / mL; free T4: 2.1 ng / dL; TSH: 2.15 IU(u / mL)

mike stevens
Guest
mike stevens

I’m on 175 mcg of Levothyroxine daily, by the way!

Christi Alex
Guest
Christi Alex

I feel so much better on Cytomel but my hair won’t stop falling out. What should I do?

Ann
Guest
Ann

I have been on a thyroid roller coaster for the past 2-3 years. I was on 1.25 mg of Synthroid and still felt awful. My doctor switched me to Naturthroid and gradually increased my dosage because my symptoms of hypothyroidism were not improving. I ended up losing over 30 pounds and my heart started racing and I was not able to sleep. They took me off the Naturthroid and put me back on Synthroid. They’ve gradually increased my Synthroid dosage to 1.00mg. I am still tired especially in the evenings, I’m slightly constipated and occasionally cold, my hair is falling… Read more »

Kim
Guest
Kim

How do I find an endocrinologist that will take my concerns seriously? Even my primary doctor whom I’ve seen for years refuses to do a reverse t3. I had a rt3 done that was very elevated but that was nearly 10 years ago and I never received treatment. I’m so exhausted and I can’t get any weight off! I’m so sick of doctors telling me to “just lose weight.”

Russ
Guest
Russ

Kim, to answer how to find an endo? I have found success in finding a Provider who would prescribe NDT by going to local pharmacies and asking what doctors prescribed it. Then, when I wanted to take T3 (high RT3), did the same again and found a provider. Not all pharmacies will help so you need to go to several (12 on my list). Now my challenge is to find a doctor who will focus more on T4, FT4, T3, RT3 and not be so obsessed with TSH (NDT or T3 forces TSH low). Six doctors in two years lol.… Read more »

Mary
Guest
Mary

My TSH is 0.059, T4F is 0.5, T3F is 3 and
T3Reverse is 5.5. I have had 1/2 of my thyroid removed 11 yrs ago and have never in 30 yrs actually felt good! I’ve been on synthyroid, naturthroid & cytomel in all combinations. Have been told I don’t convert T4 to T3. Recent ultrasound showed my remaining thyroid was dying & measured 2 centimeters! I’m currently on .75 synthroid & 25mcg cytomel (T3) a day! Can anyone help?

Sophia
Guest
Sophia

Had TT back in Dec’17, and the weight gain started creeping back up. Prior to TT, my Hashismotos don’t convert well, so my Endo put me on a 2 grain Nature and 50mcg Euthyrox. Post TT, she decided to cut down to 1.5 grain and recently in June wanted to go further down to 1 grain (which I refused) as my numbers seem to trend on the Hyper side. We compromised with 1.5 grain + Calcium supplements. I wonder if I would have put on a lot more weight if I took 1 grain instead. Do i need to get… Read more »

Guy
Guest
Guy

I’m 33, male, good shape. Family history of thyroid issues. All my levels are good…except my reverse T3 is 29! Yikes. My symtoms are horrible and have gotten worse. I feel very tense, anxious..pain develops in my throat, jaw.. sometimes feel short of breath. I have just done a comp. Thyroid panel and have the results. Wondering best doctor to see. I’ve read that I should take pure T3 to bring this level down and basically find the true source of my problem.

Elke H
Guest
Elke H

So, I have been on levothyroxine for 14 years and my dosage has not decreased or increased. originally I was told my t4 and t3 levels were in the “normal range” but then a rt3 showed I in fact had and still have a hypothyroid issue. For the last 5 years my medication (whether its not the right dosage or wrong meds) has not been helping . I’m constantly tired even though I maintain a healthy live style- working out, meal prepping, vitamins and lots of sleep. My weight is consistent no loss even though I work out like crazy.… Read more »

Kristen
Guest
Kristen

Hello. I had some blood work done. I feel like something futrther needs to be looked st after reading your article. Here are my recent thyroid results….please help.
TSH 1.190
T4 7.7
T3 uptake 25
Reverse T3 24.9
I have a full panel of thyroid if more info is needed. I’m concerned about rt3. Thank you.

Deanna Poteete
Guest
Deanna Poteete

My doctor had a full thyroid panel done and the lab stated that they could not test my RT3 because something in my blood was interfering with the test. What would interfere with this test?

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