When compared to thyroxine (T4) the thyroid hormone known as triiodothyronine (T3) is much more potent.
T3 helps ‘rev’ up your body. It increases the rate at which you burn calories for energy.
Under normal conditions T4 converts to both T3 and ‘reverse T3’ which is the inactive form of T3. The body maintains a healthy T3 to reverse T3 ratio to control an optimal metabolic rate. Reverse T3 is quickly eliminated if it is not required to slow metabolism.
What happens when too much T4 is shunted towards production of reverse T3 and this thyroid hormone pools in the body?
Excessive amounts of reverse T3 will block the effects of active T3. Ongoing excess production of reverse T3 leads to a low thyroid disorder called ‘reverse T3 dominance’. Reverse T3 dominance is associated with many of the typical symptoms of hypothyroidism.
Testing for reverse T3
Only a specific blood test for reverse T3 (rT3) will identify high levels of this inactive form of T3. Most importantly, an assessment of reverse T3 takes on far greater meaning when the total amount of reverse T3 is compared to the total amount of ‘free T3’. A drop in free T3 can be accompanied by an increase in reverse T3.
There is a simple equation to work out your reverse T3/T3 ratio. You will need your blood test results for both free T3 and reverse T3 to do this.
Watch this Video Below Here – Understanding Thyroid Function Tests
How to calculate your reverse T3/T3 ratio
To work out your reverse T3/T3 ratio divide the total free T3 by the total reverse T3 and multiply this by 100.
As of July 2016, Australian pathology labs are using a reference range of 1.200 – 2.200.
If your reverse T3/T3 ratio is at the lower end, or below this range it indicates you have a thyroid hormone imbalance.
Your thyroid blood results can be a little confusing. Here is a real example to help explain how you can calculate your own reverse T3/T3 ratio.
The free T3 test result is 4.3 pmol/L and reverse T3 is 704 pmol/L. To work out the reverse T3 ratio divide 4.3 by 704 then multiply this by 100. The result is 0.610 which is well below the healthy range, and indicates this individual is dealing with reverse T3 dominance.
Watch this Video Below Here – Thyroid Lab Testing – Thyroid Lab Ranges – Hypothyroid Patterns
Is single T3 thyroid medication ideal?
There is no one size fits all approach to reducing high reverse T3 levels. A combination of T4/T3, or a single T3 medication may be appropriate for you. It is important to work with a healthcare practitioner who understands your thyroid issues.
Care needs to be taken with taking too much T4 as this provides the body with a greater amount of T4 with the potential to create even more reverse T3. This can perpetuate the cycle of reverse T3 production.
Thyroid medications may take a little while to work as it takes time for the excess reverse T3 to clear from the body. To properly treat reverse T3 dominance it is very important to look at the individual factors that are causing this thyroid disorder.
You can read what causes high reverse T3 on this blog post.
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Louise O’ Connor, the author of The Natural Thyroid Diet –The 4-Week Plan to Living Well, Living Vibrantly, who is a specialist in Thyroid Health. She is a highly regarded Australian Naturopath and founder of Wellnesswork.
The Natural Thyroid Diet goes beyond diet advice and offers practical and effective ways to achieve healthy thyroid levels within just a short period of time. For more details, Click on The-Natural-Thyroid-Diet.com