Pronunciation: (thī-rok'sēn, -sin), [key]
1. Biochem.the thyroid gland hormone that regulates the metabolic rate of the body.
2. Pharm.a commercial form of this compound, obtained from the thyroid glands of animals or synthesized, used in the treatment of hypothyroidism. Symbol: T4 Also,thy•rox•inPronunciation: (thī-rok'sin). [key]
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.