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Is rT3 blocking your thyroid function?
In a normal functioning thyroid, the pituitary gland produces TSH - when a healthy thyroid gets this message, it produces two hormones - triiodothyronine (T3) and thyroxine (T4). T4 is converted to T3 on an as-needed basis to regulate metabolic functions.
Your liver also converts T4 to rT3 (reverse T3) which is inactive and actually blocks the action of T3. This is part of the body's normal process to keep your hormones in balance and get rid of unneeded T4. Normally about 40% of T4 is converted to T3 and 20% to rT3. However if the proportion of rT3 dominates then it can produce hypothyroid symptoms, even though your thyroid function test results may appear normal.
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The balance of rT3 to T3 can be disrupted by a number of factors, most notably because of:
- an inappropriate response to stress - which can result in too much cortisol, or too little cortisol in the case of Adrenal Fatigue
- inadequate iron levels
- other chronic illnesses
Understanding circulating rT3 levels with a reverse T3 test can provide important insights to understand the link between a thyroid disorder or adrenal hormone imbalance.