Hormones are signal molecules. They are send out by a cell to interact with receptors on other cells and surfaces. Some hormones have very specific receptors while others use more general receptor systems as well.

T4 is converted to T3 or RT3 by removal of an iodine from one of two different locations.  The ratio of conversion to T3 vs RT3 is influenced by several other factors, including cortisol/stress level,  levels of other hormones, and other signalling from the biome.  Bile acids are molecules made by the liver and contained in the bile. They not only help with fat processing, they act as hormones and have a direct effect on thryoid conversion.  (For more information on bile acids, click here.)

For videos demonstrating the conversions, see the menu at the top

Depending upon the combinations of several factors, TSH can be an accurate or inaccurate measure of the body’s true need for thyroid hormones.  TSH can only be interpreted when the T4, T3 and RT3 are considered. Therefore TSH is a secondary value and can/should not be used to adjust thyroid hormone levels.  However, it can serve as a subjective measure of iodine intake, stress, and pituitary and hypothalamic function.