thyroxine

noun

thy·​rox·​ine thī-ˈräk-ˌsēn 

-sən

variants or thyroxin

: an iodine-containing hormone C₁₅H₁₁I₄NO₄ that is an amino acid produced by the thyroid gland as a product of the cleavage of thyroglobulin, increases metabolic rate, and is used to treat thyroid disorders

called also T4

Examples of thyroxine in a Sentence

Recent Examples on the Web

These include thyroid-stimulating hormone, or TSH, which stimulates the thyroid gland to release two other hormones: triiodothyronine, or T3, and thyroxine, or T4. —Brad Reisfeld, Discover Magazine, 12 Feb. 2024

Top up your vitamin D The hormone thyroxine helps to control our ability to produce energy. —Georgia Day, Glamour, 1 Jan. 2024

The amino acid l-tyrosine will boost your metabolic rate and production of human growth hormone and thyroxine, while reducing depression and stress (19). —Amber Smith, Discover Magazine, 6 Oct. 2023

When the lab detects an FSH result above a certain level, Modern Fertility will automatically send an additional (free) test kit to test for your levels of free thyroxine (fT4), which is another thyroid hormone. —Lindsay Modglin, Health, 1 Sep. 2023

Large amounts of elemental calcium do decrease the absorption of the thyroid hormone, thyroxine (Synthroid and others). —Dr. Keith Roach, oregonlive, 6 June 2023

Women have too much cortisol, vloggers and influencers say; or not enough thyroxine, or the wrong ratio of progesterone to estradiol. —Ali Pattillo, The Atlantic, 16 June 2023

One hour is probably adequate enough to separate calcium from thyroxine. —Dr. Keith Roach, oregonlive, 6 June 2023

Some of these include luteinizing hormone or LH (which controls the release of eggs during the menstrual cycle), estradiol (which is produced by the ovaries and helps maintain the reproductive system), and free thyroxine or fT4, which is the main hormone produced by the thyroid. —Sarah Bradley, Peoplemag, 12 Apr. 2023

Word History

Etymology

alteration (by substitution of the suffix -ine entry 2 for -in entry 1) of earlier thyroxin, shortened from thyro-oxy-indol, from thyro- + oxy + indole

Note: The name was introduced by the American biochemist Edward Calvin Kendall (1886-1972) in "The thyroid hormone and its relation to the other ductless glands," Endocrinology, vol. 2 (1918), p. 90. The change of suffix was made when it was realized that the compound had an amino acid as a nucleus rather than indole, as Kendall had believed. (See A.T. Cameron, "Designation of thyroxine," Nature, vol. 119, June 25, 1927, p. 925.)

First Known Use

1918, in the meaning defined above

Kids Definition

thyroxine

noun

thy·​rox·​ine

variants or thyroxin

thī-ˈräk-sən 

-ˌsēn

: an iodine-containing hormone that is produced by the thyroid gland and is used to treat thyroid disorders

Medical Definition

thyroxine

noun

thy·​rox·​ine

variants or thyroxin

thī-ˈräk-ˌsēn, -sən 

: an iodine-containing hormone C₁₅H₁₁I₄NO₄ that is an amino acid produced by the thyroid gland as a product of the cleavage of thyroglobulin, that increases the metabolic rate, and that is used to treat thyroid disorders

called also T4