Iodine combines with the amino acid, Tyrosine, to form T1 and T2 molecules which, in turn, form T3 (T1+T2) and T4 (T2+T2) molecules. T3 is a more biologically active thyroid hormone than T4 yet more T4 is usually made by the body.
T4 is a considered a pre-hormone. It must be converted to T3 for the body to use it. The process of going from T4 to T3 is called deiodination or losing one molecule of Iodine. This takes place in places like the liver or ki
dneys. Most important, the deiodination of T4 requires zinc to happen.
Low levels of T3 and T4 signal the body to release TSH,, Thyroid Stimulating Hormones, to make more thyroid hormones. Certain lifestyle factors can cause a rise in TSH. These include illness, stress, low body temperature, poor sleep and pregnancy.