The thyroid is an endocrine gland located in the front of the neck. It is shaped like a butterfly as the two lobes wrap around the windpipe and are joined by a bridge of tissue.
Many refer to it as the “master gland of metabolism” as its affects almost every cell in the body. Through the production of two key hormones – T3 (Triiodothyronine) and T4 (Thyroxine) that interact with several other hormones in the body, it regulates key functions like metabolism, body temperature, heart rate etc. These hormones are secreted in response to a pituitary hormone, TSH (Thyroid stimulating Hormone) that stimulates the thyroid gland.
Thyroid and rT3
Our liver can constantly convert T4 to reverse T3 (rT3), the inactive form of T3, to remove any unwanted excess T4. Around 40% of T4 is converted to T3, whereas 20% of T4 is converted to rT3. However, in some cases this percentage can rise to produce 50% rT3 due to emotional, physical and biological stress.
Why Do We Make too Much rT3?
- High cortisol levels inhibit T4 conversion to T3, making more rT3.
- Low cortisol levels affect the body’s ability to maintain high cortisol levels, increasing rT3 levels.
- Low iron levels cause an inability of thyroid hormones to be removed, raising T4 levels and rT3 being produced to remove excess T4.
Other Factors Affecting rT3 Levels
- Lyme disease
- Chronic illness
- Physical injury
Symptoms of rT3 Disorder
- Increased hypothyroidism
- Constant fatigue
- Anxiety and depression due to increased adrenalin
- Thinning hair and noticeable hair loss
- Sensitive to cold weather (feel cold easily and all the time)
- Muscle aches, joint pain
These are some of the symptoms, but they can vary among individuals.
Treating rT3 Problems
It is important to identify the cause of why the body is producing excess rT3 through a blood test before taking medication and making lifestyle changes. Some ways in which we can lower rT3 levels include:
- Lower the amount of NDT intake.
- Alternatively, combining NDT with T3 has been effective as T3 is being added directly into the body.
- Supplements that support liver and intestinal function should include zinc and selenium as these have shown to increase T4 to T3 conversion, reducing rT3 levels.