thyrotrōˈpin or thyrotrōˈphin noun

A hormone, produced in the anterior lobe of the pituitary gland, which stimulates the thyroid gland

thyroxˈin or thyroxˈine noun

1. An iodine compound, the hormone forming the active principle of the thyroid gland
2. A synthetic form of this, used to treat underactivity of the thyroid gland