Reverse T3

What is Reverse T3?

T3 is a hormone that provides your body with energy. While many have heard about the T3 hormone; very few know the reverse T3, also referred to as RT3. T3 being the energy provider to the body, one has to think of RT3 as the brakes. In other words, RT3 is an important factor that helps the push/pull balancing system of our body. It is an isomer of thyroid hormones that acts in an opposite way of the T3.

When your thyroid is functioning properly, it secretes two main types of thyroid hormones: the triiodothyronine (T3) and the thyroxine (T4). T4 is considered the storage of thyroid hormones, it barely has effects as it is. T4 has to be converted into an active T3 to start doing its role as the T3 is far more powerful than the T4. When T4 is converted into T3, it’s an easy process and depends on the body’s demand for T3. However, sometimes the conversion happens differently. T4 gets converted into an inactive form of T3 that is called RT3. In other words, for the body to be able to use the thyroid hormone it needs to convert the T4 into an active form of T3. T4 can be converted into active T3 by removing a specific iodine atom. When different iodine atoms are removed, the result would be a reverse T3. Thyroids that are healthy and properly functioning convert forty percent of T4 into T3 and only 20% into RT3, daily. But, when the gland is not functioning well, this conversion rate changes to fifty percent being translated into RT3. This will impact thyroid function and disrupts the correct availability of hormones.

T3 plays an important role in our metabolism. When our body needs to boost its metabolic rate, it asks for T3; however, when the metabolism needs to be slowed down, RT3 is what it needs. Our system has the ability to dissipate RT3 when not needed anymore; but, in some cases, RT3 builds up in our blood and starts accumulating. This is normally referred to as “T3 dominance” that needs to be addressed properly.

Why take the Reverse T3 test?

The Reverse T3 test measures the levels of RT3 in the blood. When the RT3 levels in your blood are higher than needed, T3 are probably not doing their job the right way. This will lead to a state of hypothyroidism. Abnormally high levels of T3 can cause many symptoms such as feeling tired all day, having a very cold body temperature, experiencing abnormal hair loss, not being able to lose or gain weight, having low blood pressure and a slow heart rate, witnessing many mild to severe mood swings, or feeling depressed. Other symptoms that indicate an abnormal level of RT3 include having a foggy brain, swelling around the throat, being easily irritated and stressed, having muscles aches and joints aches, having dry and pale skin, having bad digestion, or experiencing swollen face, hands, and feet. Women might experience menstrual issues. All these are alarming symptoms that need to be addressed properly by getting tested for RT3.

The RT3 test is the only method to measure RT3 in our body. Many doctors, especially in the naturopathic and Integrative world, use this test as a tool to diagnose and manage hypothyroidism.

What can cause the Reverse T3 levels to rise?

Many factors lead to an increased level of RT3. These include chronic fatigue, acute illness or injuries, chronic diseases (diabetes, liver cirrhosis, fatty liver, renal failure and others), high levels of cortisol that are triggered by extreme stress, low levels of cortisol that are caused by adrenal fatigue, low iron, lyme disease and chronic inflammation.

Other factors include the long-term use of beta-blocker medicines like propranolol, metoprolol and others. A physical injury or an illness like the flu can cause a spike in RT3. Starvation and very low caloric intakes can increase the RT3; as well as detoxifying of high heavy metals.

What your Reverse T3 test results mean?

Normal Reverse T3 levels need to be between 10 and 24 ng/dL or 230-540 pmol/L. When levels are higher than 540 pmol/L, you have T3 dominance, also referred to as Wilson’s Syndrome, that needs to be addressed properly.

Where can I get a Reverse T3 test near me?

Please use our Lab Locator to find find a convenient reverse T3 testing location.

Reviewed By: Dr. Kurt Kloss, MD
Last Reviewed Date: Apr 20, 2022