Blog — rT3

Part 2 By Margaret Groves As more health care practitioners have understood the need to assess thyroid function based on what is going on at the cellular level, there has been an increasing demand for testing of reverse T3 (rT3), a hormone sometimes referred to as the “hibernation hormone.” However, there is also much confusion about how it fits into the picture of thyroid function, and controversy regarding whether or not there is a clinical utility for this test in patients suffering from thyroid imbalance symptoms. The “hibernation hormone” that isn’t Technically, the term “hibernation hormone” is inappropriate to describe reverse T3.  Reverse...

Part 1 By Margaret Groves, ZRT Laboratory Thyroid hormones are essential for the normal metabolic functioning of all tissues in the body, and a wide array of symptoms are therefore associated with abnormalities in thyroid hormone production and activation. Even when apparently adequate amounts of thyroxine are produced by the thyroid gland, thyroid function is profoundly affected by anything that disrupts conversion of thyroxine (T4) to the active thyroid hormone, triiodothyronine (T3). This conversion takes place primarily at the cellular level within tissues; only 20% of circulating T3 is generated by conversion of T4 within the thyroid gland itself. The deiodinases...