The Symptoms of High Reverse T3 You Need To Know About

Worried that high reverse T3 may cause problems? What are the causes of high reverse T3 anyway? What happens when normal tsh levels are not so normal? Lets get into it.

Background Biochemistry Of T4 And T3

It all starts with T3 and T4. The pituitary gland in the brain secretes Thyroid Stimulating Hormone (TSH), which tells the thyroid to secrete T4, which then needs to be converted in the body into T3 – this is the process of conversion from T4 to T3. A group of enzymes called deiodinases does this conversion from T4 into T3. These enzymes are found in the liver, kidney, thyroid gland, and in certain areas of the brain.

The deiodinases convert T4 into either T3 or reverse T3 (rT3). Reverse T3 is an inactive form of T3 that binds to receptor sites on cells but does not activate them.

The ratio of active T3 level to reverse T3 in the blood is a good indicator of how well the body is converting T4 into T3. A high ratio indicates that the body is converting T4 into T3 efficiently, while a low ratio indicates that the body is not converting T4 into T3 efficiently.

The deiodinases are also responsible for converting T4 into triiodothyronine (T2), which is a less active form of T3.

In addition to the deiodinases, there are other enzymes that can convert T4 into other thyroid hormones, such as thyroxine-binding globulin (TBG) and thyroxine-binding prealbumin (TBPA). However, these enzymes are not as important in regulating thyroid hormone levels as the deiodinases.

Hypothyroidism occurs when thyroid hormone levels are too low (low t3), while hyperthyroidism results from thyroid hormone levels that are too high.

What Is High Reverse T3 Level

Reverse T3 (RT3) is considered a biologically inactive thyroid hormone. For this reason, high RT3 levels are associated with a range of hypothyroid symptoms. This article discusses the function of RT3, its relationship to thyroid hormone levels, and how it may be involved in hypothyroidism.

T3 contains the same number of iodine molecules as reverse T3, but the iodine molecules are attached in a different way.

Reverse T3 (RT3) is a thyroid hormone that’s produced when the body converts too much thyroxine (T4) to triiodothyronine (T3). RT3 is biologically inactive and can’t be used by the body. Instead, it competes with T3 for binding sites on cellular receptors. This prevents T3 from exerting its normal effects on metabolism.

Elevated reverse T3 levels are associated with low levels of free T3, the active form of thyroid hormone. This can lead to symptoms such as fatigue, weight gain, hair loss, cold intolerance, and constipation. RT3 may also play a role in other conditions associated with low thyroid function, such as fibromyalgia and chronic fatigue syndrome.

The normal range for RT3 is 9-24 ng/dL (nanograms per deciliter). A level above 24 ng/dL is considered high.

The Symptoms of High Reverse T3 You Need To Know About

There are several things that cause your rT3 levels to increase, including illness, starvation, and excess cortisol (stress).

One of the main jobs of the thyroid hormones is to regulate energy metabolism. For this reason, when reverse T3 is elevated it slows metabolism which leads to a range of symptoms of hypothyroidism. People with hypothyroidism may show the following symptoms;

  • Ongoing fatigue.
  • Feeling cold all the time.
  • Difficulty losing weight, or gaining weight easily.
  • Noticeable hair loss.
  • Low blood pressure and heart palpitations.
  • Slower than normal pulse rate.
  • Mood swings that range from mild to severe.
  • Depression and anxiety.
  • Brain fog, poor memory and concentration.
  • Swelling around the throat or hoarseness.
  • Muscles aches and joint pain.
  • For women, menstrual problems or irregular periods.
  • Dry and flaky skin.
  • Sluggish digestion and constipation.
  • Face, hands and feet are swollen and puffy.
  • Low sex-drive, you have lost your MOJO!

Why Does The Body Produce Excess Reverse T3?

Elevated RT3 occurs for a number of reasons. Too much stress, chronic illness, calorie restriction, long-standing infections, systemic low-grade inflammation, hard-wired genetic traits, and an unhealthy diet are all factors to consider.

Maintaining An Optimal T3/RT3 Balance

It’s important the body maintains an optimal balance of triiodothyronine (T3) and RT3. In a clinical setting high serum reverse T3 (RT3) indicates greater amounts of thyroxine (free T4) are converting to RT3.

Let me explain more.

As you may already know the body naturally produces ample amounts of T4. In fact, T4 is often termed a ‘pro-hormone’ as it is converted to T3 when the body needs to ramp up thyroid hormone activity.

T3 is running the show…so this is the reason WHY adequate T3 makes a significant difference to how you feel.

In contrast, RT3 slows metabolism to keep your metabolic rate in check. This means that at every given moment your body is working hard to maintain an optimal balance of both T3 and RT3 to keep your metabolic rate going at a steady pace. When there’s an imbalance things start to go wrong.

High RT3 Has a Powerful Effect on Slowing Metabolism

What happens when RT3 pools in the body?

Elevated RT3 often indicates less T4 is converting to T3. In effect, the T4 is being diverted towards the production of RT3.

So when you have higher levels of circulating RT3, there is far less free T3 available.

The Importance of The Reverse T3 Test

Many of the symptoms of excess reverse T3 are non-specific so it’s important to get proper testing. I recommend you get a complete thyroid panel that includes the specific RT3 test as it’s an extremely useful biomarker.

The reverse T3 (RT3) test measures circulating levels of RT3. As you can imagine, this common thyroid disorder is easily missed if this specific test is not done.

Unfortunately, testing RT3 remains controversial. For that matter, you may even find some doctors refuse to authorize testing. If you are struggling to get proper testing there’s an alternative…order the tests you need online.

In Australia?

i-screen, Australia makes it easy to order a Reverse T3 Check. No doctor referral is necessary. It’s possible to order online and get results sent directly to you. Click here to find out more: Order your Reverse T3 Check today!

In the USA?

Take back control and order the tests you need with True Health Labs. This company offer the Complete Thyroid Test Panel to give you deeper insights into the complexity of your thyroid health. The Complete Thyroid Test Panel includes the RT3 test. You can go to the True Health Labs website for more information: Order the thyroid tests you need today!

Please note: This post contains affiliate links, to find out more about my affiliate policy please refer to my Terms of Service.


Q: What are the symptoms of high reverse T3 thyroid hormone?

A: The symptoms of high reverse T3 thyroid hormone can vary but may include fatigue, weight gain, depression, brain fog, and low body temperature.

Q: What is the role of thyroid hormones in the body?

A: Thyroid hormones play a crucial role in regulating the body’s metabolism, energy production, and growth.

Q: What is reverse T3?

A: Reverse T3, also known as reverse triiodothyronine, is an inactive form of the thyroid hormone that is produced in small amounts in the body.

Q: What is the normal range for reverse T3 levels?

A: The normal range for reverse T3 levels can vary depending on the laboratory, but it is generally between 9 to 27 ng/dL.

Q: What causes high reverse T3 levels?

A: High reverse T3 levels can be caused by various factors, including thyroid dysfunction, chronic illness syndrome, and changes in thyroid hormone metabolism.

Q: Can thyroid disease affect reverse T3 levels?

A: Yes, thyroid disease can affect reverse T3 levels. Certain thyroid disorders, such as low T3 syndrome or euthyroid sick syndrome, can lead to high levels of reverse T3.

Q: How is high reverse T3 diagnosed?

A: High reverse T3 can be diagnosed through a blood test that measures the levels of reverse T3 in the serum.

Q: Is high reverse T3 a common condition?

A: High reverse T3 is not as common as other thyroid conditions, but it can occur in some individuals, especially those with underlying thyroid dysfunction or chronic illness.

Q: Can high reverse T3 be treated?

A: Yes, high reverse T3 can be treated by addressing the underlying cause, such as treating any thyroid dysfunction or managing chronic illness syndrome.

Q: What is the significance of the ratio of T3 to reverse T3?

A: The ratio of T3 to reverse T3 is important in determining the active state of thyroid hormone metabolism. A higher ratio suggests that more T3 is available for use by the body.


In conclusion, understanding the symptoms and causes of high reverse T3 is crucial for managing thyroid health. Reverse T3 is an inactive form of thyroid hormone that can compete with T3 for binding sites on cellular receptors, leading to a range of hypothyroid symptoms. The ratio of active T3 to reverse T3 in the blood is an indicator of how well the body is converting T4 into T3. Elevated levels of reverse T3 can be caused by factors such as illness, starvation, and excess cortisol.

Thyroid hormone conversion is a complex process involving enzymes called deiodinases, which convert T4 into T3 or reverse T3. Other enzymes like thyroxine-binding globulin and thyroxine-binding prealbumin can also convert T4 into other thyroid hormones, but they play a less significant role.

Testing for reverse T3 levels is important for diagnosing and managing thyroid conditions. The reverse T3 test measures circulating levels of reverse T3 and can help identify the underlying causes of high reverse T3.

Treatment for high reverse T3 involves addressing the underlying factors, such as thyroid dysfunction or chronic illness syndrome. Balancing the levels of T3 and reverse T3 is crucial for optimal metabolic function, as an imbalance can lead to symptoms like fatigue, weight gain, depression, and low body temperature.

In summary, understanding the intricate workings of thyroid hormones, including T3, T4, and reverse T3, is essential for managing thyroid health. Regular thyroid lab tests, including measurements of free T3 and free T4, can provide valuable insights into thyroid hormone production and conversion. Consulting with a healthcare practitioner and maintaining optimal iron levels can also help reduce reverse T3 levels. By addressing the underlying causes and optimizing thyroid hormone balance, individuals can alleviate symptoms of low thyroid and improve overall well-being.


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Additional Search Based Information

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The most common symptoms of elevated reverse T3 levels include unexplained weight gain, fatigue, brain fog, hair loss, feeling cold, constipation, muscle weakness, depression, and other hypothyroidism symptoms. High reverse T3 indicates thyroid hormone resistance at the cellular level, preventing T3 from activating properly.

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High reverse T3 levels mean you have high levels of an inactive form of T3 thyroid hormone, indicating poor cellular conversion of inactive T4 to active T3. This prevents T3 from properly activating your metabolism. Causes include chronic stress, inflammation, leptin resistance, sleep deprivation, insulin resistance, toxicity, nutrient deficiencies, and certain medications.

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Common causes of elevated reverse T3 are chronic stress, high cortisol, blood sugar imbalances, leptin resistance, inflammation, critical illness, chronic dieting, calorie restriction, nutrient deficiencies like iron/selenium/zinc, liver issues, toxicity, lack of sleep, insulin resistance, and certain medications.

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Improving reverse T3 involves addressing the underlying cause, like lowering inflammation, fixing insulin resistance, reducing stress, getting more sleep, correcting nutrient deficiencies, or changing medications. Nutritional supplements, light exercise, stress management, and healing the gut can also help normalize reverse T3 levels.

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Symptoms of low reverse T3 can include rapid heart rate/palpitations, hand tremor, trouble sleeping, anxiety, irritability, muscle weakness, loose stools, hair loss, weight loss, feeling hot, and other hyperthyroidism symptoms. Low levels indicate excessive conversion of inactive T4 to active T3.

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