But TSH is a Pituitary hormone, not a thyroid hormone, the pituitary senses the amount of thyroid hormone in the system, then sends a
hormone(Thyroid Stimulating
Hormone) to the thyroid when the
hormone level is low, The thyroid produces the hormone T4, then the body converts it to T3, this is the hormone the body needs to function, they are known as Free T4 and Free T3, these two are tests that should be taken to determine thyroid balance.