AskDefine | Define thyroxine

Dictionary Definition

thyroxine n : hormone produced by the thyroid glands to regulate metabolism by controlling the rate of oxidation in cells; "thyroxine is 65% iodine" [syn: thyroxin, tetraiodothyronine, T]

User Contributed Dictionary



  1. A hormone (an iodine derivative of tyrosine), produced by the thyroid gland, that regulates cell metabolism and growth.


the hormone

Extensive Definition

Thyroxine, or 3,5,3',5'-tetra­iodothyronine (often abbreviated as T4), a form of thyroid hormones is the major hormone secreted by the follicular cells of the thyroid gland.
T4 is transported in blood, with 99.95% of the secreted T4 being protein bound, principally to thyroxine-binding globulin (TBG), and, to a lesser extent, to transthyretin and serum albumin. T4 is involved in controlling the rate of metabolic processes in the body and influencing physical development.
Note: Thyroxine is a prohormone and a reservoir for the active thyroid hormone triiodothyronine (T3). T4 is converted in the tissues by deiodinases to T3. The "D" isomer is called "Dextrothyroxine" and is used as a lipid modifying agent. The half-life of thyroxine once released into the blood circulatory system is about 1 week.
The hormone was synthesised in 1927 by British chemists Charles Robert Harington and George Barger.


thyroxine in Arabic: ثيروكسين
thyroxine in Bulgarian: Тироксин
thyroxine in Czech: Thyroxin
thyroxine in Danish: Thyroxin
thyroxine in German: Thyroxin
thyroxine in Dhivehi: ތައިރޮކްސިން
thyroxine in Spanish: Tiroxina
thyroxine in Estonian: Türoksiin
thyroxine in Finnish: Tyroksiini
thyroxine in French: Thyroxine
thyroxine in Hebrew: תירוקסין
thyroxine in Italian: Tiroxina
thyroxine in Japanese: サイロキシン
thyroxine in Lithuanian: Tiroksinas
thyroxine in Dutch: Thyroxine
thyroxine in Polish: Tyroksyna
thyroxine in Portuguese: Tiroxina
thyroxine in Swedish: Tyroxin
thyroxine in Turkish: Tiroksin
thyroxine in Chinese: 甲狀腺素
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