Thyroid hormones

thyroid hormonethyroxineT4thyroxinT 4 thyroidThyroid hormone replacementthyroxine (T4)free T4free thyroid hormones
Thyroid hormones are two hormones produced and released by the thyroid gland, namely triiodothyronine (T 3 ) and thyroxine (T 4 ).wikipedia
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Triiodothyronine

T 3 T3triiodothyronine (T3)
Thyroid hormones are two hormones produced and released by the thyroid gland, namely triiodothyronine (T 3 ) and thyroxine (T 4 ).
Triiodothyronine, also known as T 3, is a thyroid hormone.

Iodine

II 2 iodinated
T 3 and T 4 are partially composed of iodine.
Iodine is essential in the synthesis of thyroid hormones.

Levothyroxine

Synthroidlevothyroxine sodiumLevothroid
In 2016 levothyroxine, a manufactured form of thyroxine, was the most prescribed medication in the United States with more than 114 million prescriptions.
Levothyroxine, also known as L-thyroxine, is a manufactured form of the thyroid hormone thyroxine (T 4 ).

Selenium

SeSe 3 selenium poisoning
All three isoforms of the deiodinases are selenium-containing enzymes, thus dietary selenium is essential for T 3 production.
It is also found in three deiodinase enzymes, which convert one thyroid hormone to another.

Deiodinase

Deiodinase enzymesdeiodinasestetraiodothyronine 5' deiodinase
T 4 is converted to the active T 3 (three to four times more potent than T 4 ) within cells by deiodinases (5'-iodinase).
Deiodinase (or iodide peroxidase or "Monodeiodinase") is a peroxidase enzyme that is involved in the activation or deactivation of thyroid hormones.

Hypothyroidism

hypothyroidhypo-underactive thyroid
Both T 3 and T 4 are used to treat thyroid hormone deficiency (hypothyroidism).
Hypothyroidism, also called underactive thyroid or low thyroid, is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone.

Edward Calvin Kendall

Edward C. KendallDr. Edward C. KendallE C Kendall
Edward Calvin Kendall was responsible for the isolation of thyroxine in 1915.
Kendall did not only focus on the adrenal glands, he was also responsible for the isolation of thyroxine, a hormone of the thyroid gland and worked with the team that crystallized glutathione and identified its chemical structure.

Liotrix

Thyrolar
Also available are synthetic combinations of T 3 /T 4 in different ratios (such as liotrix) and pure-T 3 medications (INN: liothyronine).
Liotrix is a 4:1 mixture of thyroxine (T 4 ) and triiodothyronine (T 3 ) made synthetically.

Liothyronine

Liothyronine SodiumCytomelTriostat
Also available are synthetic combinations of T 3 /T 4 in different ratios (such as liotrix) and pure-T 3 medications (INN: liothyronine).
Liothyronine is a manufactured form of the thyroid hormone triiodothyronine (T3).

Thyroid

thyroid glandthyroid folliclethyroid function
Thyroid hormones are two hormones produced and released by the thyroid gland, namely triiodothyronine (T 3 ) and thyroxine (T 4 ). ]]Thyroid hormones (T 4 and T 3 ) are produced by the follicular cells of the thyroid gland and are regulated by TSH made by the thyrotropes of the anterior pituitary gland. - Thyroglobulin is synthesized in the rough endoplasmic reticulum and follows the secretory pathway to enter the colloid in the lumen of the thyroid follicle by exocytosis.
The thyroid gland secretes three hormones: the two thyroid hormones, thyroxine/T 4 and triiodothyronine/T 3 ; and calcitonin.

Thyronamine

thyronamines
These are further processed by decarboxylation and deiodination to produce iodothyronamine (T 1 a) and thyronamine (T 0 a).
Thyronamine refers both to a molecule, and to derivatives of that molecule: a family of decarboxylated and deiodinated metabolites of the thyroid hormones thyroxine (T4) and 3,5,3'-triiodothyronine (T3).

Charles Harington (chemist)

Charles Robert HaringtonCharles HaringtonSir Charles Robert Harington
Synthetic thyroxine was first successfully produced by Charles Robert Harington and George Barger in 1926.
Sir Charles Robert Harington, KBE, FRS (1 August 1897 – 4 February 1972) was a chemist, best known for synthesizing thyroxine.

Sodium/iodide cotransporter

sodium-iodide symporterSLC5A5basolateral sodium iodide symporter
- Meanwhile, a sodium-iodide (Na/I) symporter pumps iodide (I − ) actively into the cell, which previously has crossed the endothelium by largely unknown mechanisms.
NIS mediated uptake of iodide into follicular cells of the thyroid gland is the first step in the synthesis of thyroid hormone.

Permissiveness (biology)

permissivenesspermissivepermissively
They act to increase the basal metabolic rate, affect protein synthesis, help regulate long bone growth (synergy with growth hormone) and neural maturation, and increase the body's sensitivity to catecholamines (such as adrenaline) by permissiveness.
Thyroid hormone increases the number of beta adrenergic receptors available for epinephrine at the latter's target cell, thereby increasing epinephrine's effect on that cell.

Thyroid-stimulating hormone

TSHthyroid stimulating hormonethyrotropin
]]Thyroid hormones (T 4 and T 3 ) are produced by the follicular cells of the thyroid gland and are regulated by TSH made by the thyrotropes of the anterior pituitary gland.
Thyroid-stimulating hormone (also known as thyrotropin, thyrotropic hormone, or abbreviated TSH) is a pituitary hormone that stimulates the thyroid gland to produce thyroxine (T 4 ), and then triiodothyronine (T 3 ) which stimulates the metabolism of almost every tissue in the body.

Follicular cell

follicular cellsThyroid epithelial cellthyroid follicular cell
]]Thyroid hormones (T 4 and T 3 ) are produced by the follicular cells of the thyroid gland and are regulated by TSH made by the thyrotropes of the anterior pituitary gland.
Follicular cells (also called thyrocytes or thyroid epithelial cells) are the major cell type in the thyroid gland and are responsible for the production and secretion of the thyroid hormones thyroxine (T4) and triiodothyronine (T3).

Desiccated thyroid extract

Desiccated thyroidArmour ThyroidNatural desiccated thyroid hormones
Natural desiccated thyroid hormones are derived from pig thyroid glands, and are a "natural" hypothyroid treatment containing 20% T 3 and traces of T 2, T 1 and calcitonin.
They contain a mixture of thyroxine (T4) and triiodothyronine (T3).

Monocarboxylate transporter 8

SLC16A2MCT8monocarboxylate transporter (MCT) 8
- Efflux of thyroxine and triiodothyronine from follicular cells, which appears to be largely through monocarboxylate transporter (MCT) 8 and 10, and entry into the blood.
MCT8 actively transports a variety of iodo-thyronines including the thyroid hormones T 3 and T 4.

Thyroglobulin

TGAnti-thyroglobulin antibodiesProloid
- Thyroglobulin is synthesized in the rough endoplasmic reticulum and follows the secretory pathway to enter the colloid in the lumen of the thyroid follicle by exocytosis. It is produced as the precursor thyroglobulin (this is not the same as thyroxine-binding globulin (TBG)), which is cleaved by enzymes to produce active T 4.
Thyroglobulin is a precursor to thyroid hormones, which are produced when thyroglobulin's tyrosine residues are combined with iodine and the protein is subsequently cleaved.

Thyroxine-binding globulin

thyroid binding globulinTBGSERPINA7
It is produced as the precursor thyroglobulin (this is not the same as thyroxine-binding globulin (TBG)), which is cleaved by enzymes to produce active T 4.
Thyroxine-binding globulin (TBG) is a globulin that binds thyroid hormones in circulation.

3-Iodotyrosine

monoiodotyrosine3-IodotyrosylIodotyrosine
3-Iodotyrosine is an intermediate in the synthesis of thyroid hormones which is derived from iodination of tyrosine at the meta-position of the benzene ring.

Iodothyronine deiodinase

DIO1thyroxine 5'-deiodinaseEC 1.97.1.10
T 4 is converted as required in the tissues by iodothyronine deiodinase.
Iodothyronine deiodinases ( and ) are a subfamily of deiodinase enzymes important in the activation and deactivation of thyroid hormones.

George Barger

Barger
Synthetic thyroxine was first successfully produced by Charles Robert Harington and George Barger in 1926.
He also made significant contributions to the synthesis of thyroxine.

Diiodotyrosine

3,5-diiodo-L-tyrosine
Diiodotyrosine (DIT) is a precursor in the production of thyroid hormone, and results from iodization of monoiodotyrosine at the other meta- position on the phenol ring.

Thyroid peroxidase

thyroperoxidaseTPOiodide peroxidase
- In the colloid, iodide (I − ) is oxidized to iodine (I 0 ) by an enzyme called thyroid peroxidase.
Thyroid peroxidase oxidizes iodide ions to form iodine atoms for addition onto tyrosine residues on thyroglobulin for the production of thyroxine (T 4 ) or triiodothyronine (T 3 ), the thyroid hormones.