Triiodothyronine

[Happy121]

Hi is Triiodothyronine the same atomic structure as liothyronine and depending how many different atomic ways are there of structuring a liothyronine molecule with the atoms needed and how many different spellings of liothyronine or something similar have people come across and are there any good books on the different atomic structures please?

[FallingInReverse]

Triiodothyronine is the naturally occurring hormone and Liothyronine is the synthetic- and they are molecularly identical.

if you changed the structure of a Lio molecule, you would no longer have Lio… as it’s the specific atomic arrangement that defines its identity and function.

I don’t know any good books. Are you just curious? Or , why do you want to know?

Disclaimer - I’m not a doctor, or scientist, and welcome all corrections : )

[helvella Administrator Thyroid UK]

The only differences that exist across all forms of T3 are:

The "extra" bit attached to the synthetic version - either sodium or hydrochloride ions;

Whether we are discussing the L- (levo-) or D- (dextro-) forms. Chemically, both can exist,. But in biology and medicine, it is always the L- form. We can always assume that safely. That is, there are potentially two forms of Triodothyronine but no-one ever discusses the D- form.

How hydrated it is. That is, how many water molecules are attached to the main molecule. This is very unimportant because, within our bodies, it will always be fully hydrated.

And reverse T3. Reverse triiodothyronine (3,3′,5′-triiodothyronine, reverse T3, or rT3) is an isomer of triiodothyronine (3,5,3′ triiodothyronine, T3). One of the hydrogen atoms is on a different carbon atom. This seems only to occur when a particular enzyme acts on a levothyroxine molecule.

Triodothyronine is a chemical name - one that describes the substance. Three iodine atoms attached to a thyronine core.

Liothyronine appears to be a made-up name for Triodothyronine when it has been synthesised. It is easier to say and to type!

Some countries seem to stick to the name Triodothyronine (or variations that make it fit the language better). Whereas other use Liothyronine.

The different spellings, with an -e at the end, with a -t- instead of -th-, etc., are all to do with adjusting the word for native speakers adopting the word into their languages and adapting it to make sense. Relatively few languages other than English use the "th" sound.

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This word separation is very helpful in that someone talking about the medicine will speak of liothyronine whereas the blood test will measure Triodothyronine (though almost always T3).

We often see L-T3 as a short form for liothyronine.

Contrast thyroxine where the same basic word is used for the substance wherever it is - in a thyroid, in our blood, in a tablet. And use of the extended for L-thyroxine or levothyroxine for the synthetic form is actually not very sensible. Because the form our own thyroids make is also the L- form.

We often see L-T4 as a short form for synthetic levothyroxine.

But the cost of that easy distinction is having two different words for what is the same thing.

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We also nowadays see desiccated thyroid described as containing certain amounts of levothyroxine and liothyronine.

Some people get very upset at this. I don't. I see it as a perfectly reasonable way of describing the hormone content. I'd be more upset by seeing the word thyroxine and at least theoretically leaving that to be D-, L- or a mixture. And reserving the word liothyronine for the synthetic form is purely a convention.

I don't think anyone is trying to mislead as to what it is or contains. And those who are aware and pick up on the issue demonstrate they understand what is meant by the fact the pick up on it!

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You will find a rabbit hole of details about liothyronine and its many names at this link. (Some are variations of the substance.):

pubchem.ncbi.nlm.nih.gov/#q...

liothyronine

triiodothyronine

3,3',5-Triiodo-L-thyronine

6893-02-3

Liothyronin

Tresitope

3,5,3'-triiodothyronine

3,5,3'-Triiodo-L-thyronine

T3

triothyrone

Liothyroninum

Liotironina

L-Liothyronine

O-(4-Hydroxy-3-iodophenyl)-3,5-diiodo-L-tyrosine

Lyothyronine

Cyronine

L-T3

3,3',5-Triiodothyronine

3,5,3'TRIIODOTHYRONINE

L-3,5,3'-Triiodothyronine

Rathyronine, (s)-

(2S)-2-amino-3-[4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl]propanoic acid

(S)-2-amino-3-(4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl)propanoic acid

L-3,3',5-TriioDOThyronine

Liotironina [INN-Spanish]

Triiodo-L-thyronine

L-Tyrosine, O-(4-hydroxy-3-iodophenyl)-3,5-diiodo-

Liothyronine (GMP)

Liothyronine (INN)

4-(4-Hydroxy-3-iodophenoxy)-3,5-diiodophenylalanine

L-triiodothyronine

Thyronine, 3,3',5-triiodo-, L-

Liothyroninum [INN-Latin]

4-(3-Iodo-4-hydroxyphenoxy)-3,5-diiodophenylalanine

4-(4-hydroxy-3-iodophenoxy)-3,5-diiodo-L-phenylalanine

3,5,3'-triiodothyronine, l-

Alanine, 3-(4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl)-, L-

LIOTHYRONINE [INN]

Liothyroninum (INN-Latin)

Liotironina (INN-Spanish)

T-3

LIOTHYRONINE (USP-RS)

T3 (amino acid)

LIOTHYRONINE (USP IMPURITY)

Liothyronine [INN:BAN]

Euthroid-1

Euthroid-2

Euthroid-3

Thyrolar-1

Thyrolar-2

Thyrolar-3

(+)-Triiodothyronine

Euthroid-0.5

Thyrolar-0.5

T3 (VAN)

Thyrolar-0.25

Triiodothyronine, l-

3,5,3'-Tri-iodo-L-thyronine

Triiodothyronine (T3)

SR-05000000455

Therapeutic T3

3,3',5-Triiodothyronine, L-

4-(3-iodo-4-hydroxy-phenoxy)-3,5-diiodophenylalanine

(2S)-2-AMINO-3-(4-(4-HYDROXY-3-IODOPHENOXY)-3,5-DIIODOPHENYL)PROPANOIC ACID

L-3-(4-(4-Hydroxy-3-iodophenoxy)-3,5-diiodophenyl)alanine

Triiodothyronine;3,3',5-Triiodo-L-thyronine;T3

THYROLAR-5

LIOTHYRONINE [MI]

LIOTHYRONINE [HSDB]

LIOTHYRONINE [VANDF]

O-(4-Hydroxy-3-iodophenyl-3,5-diiodo-L-tyrosine

3,5,3'-triodo-L-thyronine

LIOTHYRONINE [WHO-DD]

L-3,3',5-triiodo-Thyronine

TRIIODOTHYRONINE (T3 OR LIOTHYRONINE, ACTIVE) (6-11%)

3,5,3'-triiodo-L-thyronine (T3)

(S)-2-Amino-3-(4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl)propanoicacid

3,3',5-Triiodo-L-thyronine, 95%

L-3,3',5-Triiodothyronine, free acid

3,3 inverted exclamation mark ,5-Triiodo-L-thyronine

LEVOTHYROXINE SODIUM IMPURITY A [EP IMPURITY]

3,3',5-Triiodo-L-thyronine, >=95% (HPLC), powder

D-3-[4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl]alanine

L-3-[4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl]-Alanine

Liothyronine, United States Pharmacopeia (USP) Reference Standard

3,3',5 Triiodothyronine (T3), IRMM(R) certified Reference Material

O-(4-Hydroxy-3-iodophenyl)-3,5-diiodo-L-tyrosine,labeled with(125i)iodine

Liothyronine, Pharmaceutical Secondary Standard; Certified Reference Material

Tresitope , O-(4-Hydroxy-3-iodophenyl)-3,5-diiodo-L-tyrosine , Triiodothyronine , L-3,3',5-Triiodothyronine , 3,3',5-Triiodo-L-thyronine , Lyothyronine

[Happy121 in reply to helvella]

THANKYOU KINDLY for your time and knowledge.

[Zephyrbear in reply to helvella]

Wow!!! That’s quite the 🐇 🕳️!!! Incredibly interesting… just wonder where you find the time! Thank you!

[helvella Administrator Thyroid UK in reply to Zephyrbear]

The list is only copied from the link!

(And a bit of editing because lots of entries were like product numbers from chemical supplier catalogues, etc.)

[helvella Administrator Thyroid UK in reply to helvella]

You can also have fun on that site playing with several different sorts of molecular model. It will animate if you wish!

Screenshot of a ball and stick model of T3