tri·​io·​do·​thy·​ro·​nine | \ ˌtrī-ˌī-ə-dō-ˈthī-rə-ˌnēn How to pronounce triiodothyronine (audio) \

Definition of triiodothyronine

: an iodine-containing hormone C15H12I3NO4 that is an amino acid derived from thyroxine

called also T3

Examples of triiodothyronine in a Sentence

Recent Examples on the Web The hormones that the thyroid gland makes — triiodothyronine, or T3, and thyroxine, or T4 — affect all aspects of your metabolism. Mayo Clinic News Network,, "Thyroid disorder may not show symptoms until pregnancy," 4 Oct. 2019 Your thyroid produces hormones like thyroxine and triiodothyronine, which influence many of your body’s systems, according to the Mayo Clinic. Zahra Barnes, SELF, "This Is When You Should Actually Worry About Heart Palpitations," 16 Jan. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'triiodothyronine.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of triiodothyronine

1952, in the meaning defined above

History and Etymology for triiodothyronine

tri- + iod- + thyronine an amino acid of which thyroxine is a derivative

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The first known use of triiodothyronine was in 1952

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Cite this Entry

“Triiodothyronine.” Dictionary, Merriam-Webster, Accessed 30 Nov. 2020.

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tri·​io·​do·​thy·​ro·​nine | \ ˌtrī-ˌī-əd-ō-ˈthī-rə-ˌnēn How to pronounce triiodothyronine (audio) \

Medical Definition of triiodothyronine

: a crystalline iodine-containing hormone C15H12I3NO4 that is an amino acid derived from thyroxine and is used especially in the form of its soluble sodium salt C15H11I3NNaO4 in the treatment of hypothyroidism and metabolic insufficiency

called also liothyronine, T3

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