thyrotropin

(thī'rätrō`pĭn) or

thyroid-stimulating hormone

(TSH), hormonehormone,
secretory substance carried from one gland or organ of the body via the bloodstream to more or less specific tissues, where it exerts some influence upon the metabolism of the target tissue.
..... Click the link for more information. released by the anterior pituitary glandpituitary gland,
small oval endocrine gland that lies at the base of the brain. It is sometimes called the master gland of the body because all the other endocrine glands depend on its secretions for stimulation (see endocrine system).
..... Click the link for more information. that stimulates the thyroid glandthyroid gland,
endocrine gland, situated in the neck, that secretes hormones necessary for growth and proper metabolism. It consists of two lobes connected by a narrow segment called the isthmus. The lobes lie on either side of the trachea, the isthmus in front of it.
..... Click the link for more information. to release thyroxinethyroxine
, substance secreted by the thyroid gland. The hormone thyroxine forms by combining the amino acid tyrosine with iodine. Complexed to a protein, it is stored in the follicle stems between thyroid cells.
..... Click the link for more information. . The release of thyrotropin is triggered by the action of thyrotropin-releasing factor (TRF), a substance found in the hypothalamus of the brain. TRF, once released from the hypothalamus, travels in the bloodstream to the anterior pituitary, where it causes the release of thyrotropin. This latter substance, a glycoprotein (see proteinprotein,
any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight.
..... Click the link for more information. ), is carried to the thyroid gland by the blood, where it stimulates the uptake of iodine, the conversion of diiodotyrosine to thyroxine, and the secretion of thyroid hormones into the bloodstream. Thyroxine inhibits the further release of thyrotropin by interfering with the action of TRF; thus the levels of thyroid hormones are regulated. If not enough iodine is available in the diet, then not enough thyroxine will be made to shut off the release of thyrotropin. Prolonged stimulation of the thyroid by thyroid-stimulating hormone results in an abnormal enlargement of the gland, known as goiter, a condition which has been largely eradicated by the widespread usage of iodized salt.

Thyrotropin

(thyrotropic hormone, thyroid-stimulating hormone, TSH), a hormone produced by the anterior lobe of the hypophysis in vertebrate animals and man that controls the development and functions of the thyroid gland. Thyrotropin is a glycoprotein with a molecular weight of 28,000–30,000. It stimulates the splitting of the protein thyroglobulin in the thryoid follicles and the release of the active thyroid hormones, thyroxine and triiodothyronine, into the blood. It also promotes the enlargement of follicular cells, the absorption of iodine, and the synthesis of thyroxine.

The mechanism of action of thyrotropin, like that of several other hormones, is related to the hormone’s capacity to activate the synthesis of cyclic adenylic acid (cAMP), which stimulates the splitting of thyroglobulin. The synthesis and secretion of thyrotropin are controlled by the central nervous system and, primarily, by the hypothalamus, which produces the special thyrotropin releasing factor. When the concentration of thyroid hormones in the blood increases, the hormones inhibit by negative feedback the secretion of thyrotropin by acting both on the hypothalamic regulatory centers and directly on the hypophysis, causing the secretion of thyroxine and triiodothyronine to diminish. Epinephrine and the corticosteroids also suppress the secretion of thyrotropin, which accounts for the decrease in thyroid activity in various stress reactions (except cold stress). (See alsoADAPTATION SYNDROME and NEUROSECRETION.)

I. V. KRIUKOVA

thyrotropin

[thī′rä·trə·pən] (biochemistry) A thyroid-stimulating hormone produced by the adenohypophysis.

thyrotropin

[thi´ro-tro″pin, thi-rot´rah-pin] a hormone secreted by the anterior lobe of the pituitary gland" >pituitary gland that has an affinity for and specifically stimulates the thyroid gland. Called also thyroid-stimulating hormone.thyrotropin alfa a recombinant form of human thyrotropin; it binds to thyrotropin receptors and stimulates the steps in thyroid hormone synthesis, including iodine uptake and synthesis and secretion of thyroglobulin; used as a diagnostic adjunct in serum thyroglobulin testing, with or without radioiodine scanning, in followup of patients with well-differentiated thyroid cancer, administered intramuscularly.thyrotropin-releasing hormone stimulation test (thyrotropin-releasing hormone test) a thyroid function test that assesses release of thyrotropin by the pituitary gland; a bolus of hormone" >thyrotropin-releasing hormone is administered and serum concentrations of thyrotropin are assessed at intervals; if serum levels do not increase within 30 to 40 minutes, the pituitary thyrotrophs are dysfunctional. Called also TRH test and TRH stimulation test.

thy·rot·ro·pin

(thī-rot'rō-pin, thī-rō-trō'pin), A glycoprotein hormone produced by the anterior lobe of the hypophysis that stimulates the growth and function of the thyroid gland; also used as a diagnostic test to differentiate primary and secondary hypothyroidism. Synonym(s): thyroid-stimulating hormone, thyrotrophin, thyrotropic hormone [for thyrotrophin, fr. thyro- + G. throphē, nourishment; corrupted to -tropin, and reanalyzed as fr. G. tropē, a turning]

thyrotropin

(thī′rə-trō′pĭn, thī-rŏt′rə-) also

thyrotrophin

(-fĭn)n. A hormone secreted by the anterior lobe of the pituitary gland that stimulates and regulates the activity of the thyroid gland. Also called thyroid-stimulating hormone, thyrotropic hormone.

thy′ro·tro′pic (-trō′pĭk, -trŏp′ĭk), thy′ro·tro′phic (-trō′fĭk, -trŏf′ĭk) adj.

thyrotropin

Thyroid stimulating hormone. See TSH.

thy·rot·ro·pin

(thī'rō-trō'pin) A glycoprotein hormone produced by the anterior lobe of the hypophysis that stimulates the growth and function of the thyroid gland; it also is used as a diagnostic test to differentiate primary and secondary hypothyroidism.
Synonym(s): thyroid-stimulating hormone, thyrotrophin. [fr. thyro- + G. throphē, nourishment; corrupted to -tropin, and reanalyzed as fr. G. tropē, a turning]

Thyroid stimulating hormone (thyrotropin)

A hormone that stimulates the thyroid gland to produce hormones that regulate metabolism.Mentioned in: Pituitary Dwarfism

thy·rot·ro·pin

(thī'rō-trō'pin) Glycoprotein hormone produced by anterior lobe of hypophysis; also used as a diagnostic test to differentiate primary and secondary hypothyroidism. [fr. thyro- + G. throphē, nourishment; corrupted to -tropin, and reanalyzed as fr. G. tropē, a turning]

thyrotropin

thy·ro·tro·pin

thyrotropin

thyrotrophin

thy•ro•tro•pin

also thy•ro•tro•phin

thyrotropin

thyrotropin

thyroid-stimulating hormone

Thyrotropin

thyrotropin

thyrotropin

thyrotropin

thy·rot·ro·pin

thyrotropin

thyrotrophin

thyrotropin

thy·rot·ro·pin

Thyroid stimulating hormone (thyrotropin)

thy·rot·ro·pin

thyrotropin

Synonyms for thyrotropin

noun anterior pituitary hormone that stimulates the function of the thyroid gland

Synonyms

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