thyroxine


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Related to thyroxine: Levothyroxine

thyroxine

 (T4) [thi-rok´sin]
a thyroid hormone that contains iodine and is a derivative of the amino acid tyrosine, occurring naturally as l-thyroxine; its chemical name is tetraiodothyronine. It is formed and stored in the thyroid follicles as thyroglobulin and released from the gland by the action of a proteolytic enzyme. It is deiodinated in peripheral tissues to form triiodothyronine (T3), which has a greater biological activity.



Thyroxine acts as a catalyst in the body and influences a great variety of effects, including metabolic rate (oxygen consumption); growth and development; metabolism of carbohydrates, fats, proteins, electrolytes, and water; vitamin requirements; reproduction; and resistance to infection. Pharmaceutical preparations of thyroxine, extracted from animals or made synthetically, are called levothyroxine.
free thyroxine the fraction of thyroxine in the serum that is not bound to a binding protein.

thy·rox·ine (T4),

, thyroxin (thī-rok'sēn, -sin),
The l-isomer is the active iodine compound existing normally in the thyroid gland and extracted therefrom in crystalline form for therapeutic use; also prepared synthetically; used for the relief of hypothyroidism, cretinism, and myxedema.

thyroxine

/thy·rox·ine/ (T4) (thi-rok´sin) an iodine-containing hormone secreted by the thyroid gland, occurring naturally as l-thyroxine; its chief function is to increase the rate of cell metabolism. It is deiodinated in peripheral tissues to form triiodothyronine, which has greater biological activity. A preparation of thyroxine, levothyroxine, is used pharmaceutically.

thyroxine

(thī-rŏk′sēn′, -sĭn) also

thyroxin

(-rŏk′sĭn)
n.
An iodine-containing hormone, C15H11I4NO4, produced by the thyroid gland, that increases the rate of cell metabolism and regulates growth and that is made synthetically for treatment of thyroid disorders.

thyroxine (T4)

[thīrok′sēn]
a hormone of the thyroid gland, derived from tyrosine and deiodinated in the periphery to T3 (triiodothyronine) that stimulates metabolic rate. Also called tetraiodothyronine.

thyroxine

T4, 3,5,3',5'-Tetraiodothyronine A hormone that stimulates metabolism and O2 consumption, which is secreted by the thyroid gland in response to TSH–thyrotropin produced in the adenohypophysis–anterior pituitary gland ↑ in Hyperthyroidism, acute thyroiditis, myasthenia gravis, preeclampsia, pregnancy, viral hepatitis, therapy with clofibrate, OCs, estrogens, perphenazine ↓ in Hypothyroidism, malnutrition, vigorous exercise, hypofunction of adenohypophysis–anterior pituitary gland, renal failure, therapy with corticosteroids, chlorpromazine, heparin, lithium, phenytoin, propranolol, reserpine, salicylates, sulfonamides, testosterone, tolbutamide. See Triiodothyronine–T3, Thyroxine-binding globulin.

thy·rox·ine

, thyroxin (thī-rok'sēn, -sin)
The active iodine compound existing normally in the thyroid gland and extracted therefrom in crystalline form for therapeutic use; also prepared synthetically; used for the relief of hypothyroidism, congenital hypothyroidism, and myxedema.

thyroxine

The principal thyroid hormone. Thyroxine has four iodine atoms in the molecule and is often known as T4. The sodium salt of thyroxide (levothyroxine) is sold as a drug used to treat thyroid deficiency disorders (hypothyroidism) under the brand name Eltroxin.

thyroxine

a complex organic compound containing iodine which is the main hormone produced by the THYROID GLAND.

Thyroxine (T 4 )

Thyroid hormone that regulates many essential body processes.
Mentioned in: Hypothyroidism
thyroxine; T4 natural secretion of thyroid gland (also produced synthetically for treatment of underactive thyroid); converted in muscle/liver/kidney to active triiodothyronine (T3)

thy·rox·ine

, thyroxin (thī-rok'sēn, -sin)
The active iodine compound existing normally in the thyroid gland and extracted therefrom in crystalline form for therapeutic use; also prepared synthetically; used for the relief of congenital hypothyroidism, and myxedema.

thyroxine (thīrok´sin),

n the hormone secretion of the thyroid gland, L-3,5,3´,5´-tetraiodothyronine.

thyroxine, thyroxin

a hormone of the thyroid gland that contains iodine and is a derivative of the amino acid tyrosine. The chemical name for thyroxine is tetraiodothyronine (symbol, T4); it is formed and stored in the thyroid follicles as thyroglobulin, the storage form. Thyroxine is released from the gland by the action of a proteolytic enzyme. T4 is deiodinated in peripheral tissues to form tri-iodothyronine (T3), which has a greater biological activity.
Thyroxine acts as a catalyst in the body and influences a great variety of effects, including metabolic rate (oxygen consumption); growth and development; metabolism of carbohydrates, fats, proteins, electrolytes and water; vitamin requirements; reproduction; and resistance to infection.
Thyroxine can be extracted from animals or made synthetically; it is used in the treatment of hypothyroidism and some types of goiter.

free thyroxine
the metabolically active fraction of thyroxine; abbreviated FT4, Tf. T4 = Tf + TBG. The amount is very small and difficult to estimate so that the amount present in serum is not used as a more accurate indicator of thyroxine status than T4.
thyroxine-binding globulin (TBG)
most (99.95%) of the thyroxine in plasma is bound to globulin and a small amount bound to prealbumin.
thyroxine-binding prealbumin
bound to a small fraction of circulating T4. This is the only known function of prealbumins.
L-thyroxine
References in periodicals archive ?
From then on, textbooks relied on the Mayo Clinic, other "major figures," and these two misinterpreted reports, and the clinical evaluation for judging appropriate thyroxine dose went "out the window" in conventional medicine.
4) A T4 is requested if the TSH is elevated in a patient not on thyroxine replacement therapy to differentiate subclinical from overt hypothyroidism.
0 mIU/L and low free T4, the decision to start treatment with thyroxine is usually easy.
The University of Aberdeen has already identified that mice with a higher metabolic rate live longer, and greater thyroxine in the body helps this.
The drug thyroxine is used to supplement thyroid hormone when it is too low (Hypothyroidism) or when the gland is under active.
aurantium dietary supplements without any medical advice, with possible interactions with adrenergetic, antidepressant, cardiovascular drugs, and thyroxine like in the reported case.
Gonad development is increased in absence of light, due to the repression on thyroxine (2).
Diminished thyroxine (T4) levels are believed responsible for hemodynamic instability after brain death.
The text's description of the structural similarities between the three types of molecules doesn't agree with the figure of the structures of the molecules of PBDE-100, PCB-153, and thyroxine.
One chemical that affects the metabolic rate is thyroxine.
Rana catesbeiana tadpoles (hindlimb bud stage) were exposed to exogenous dilute concentrations of thyroxine.

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