- the thyroid gland hormone that regulates the metabolic rate of the body.
- a commercial form of this compound, obtained from the thyroid glands of animals or synthesized, used in the treatment of hypothyroidism. Symbol: T4
- the principal hormone produced by the thyroid gland: it increases the metabolic rate of tissues and also controls growth, as in amphibian metamorphosis. It can be synthesized or extracted from the thyroid glands of animals and used to treat hypothyroidism. Chemical name: tetra-iodothyronine; formula: C 15 H 11 I 4 NO 4
