| thyroid hormone | <endocrinology> Thyroxine and tri iodothyronine are hormones secreted by the thyroid gland in vertebrates. These iodinated aromatic amino acid compounds influence growth and metabolism and, in amphibia, metamorphosis. The hormone calcitonin which has hypocalcaemic effects is also of thyroid origin but is not usually classed with thyroxine and tri iodothyronine as a thyroid hormone. (18 Nov 1997) |
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| thyroid hormone aminotransferase | <enzyme> Chemical name: 3,5-dinitrotyrosine aminotransferase Registry number: EC 2.6.1.26 Synonym: triiodothyrone aminotransferase, triiodothyronine aminotransferase (26 Jun 1999) |
| thyroid hormone resistance syndrome | <syndrome> An inherited syndrome of peripheral resistance to thyroid hormones, transmitted as an autosomal recessive trait, characterised by increased serum concentrations of thyroxine and triiodothyronine, increased thyroid hormone binding ratio, and normal to slightly increased thyroid-stimulating hormone and its response to thyrotropin-releasing hormone. The affected persons are euthyroid to slightly hypothyroid. The absence of hypermetabolism and the presence of possible hypothyroidism indicate the existence of partial resistance to the peripheral action of thyroid hormone. (12 Dec 1998) |
| thyroid hormones | Chemical substances made by the thyroid gland which is located in the front of the neck. The thyroid gland uses iodine to make thyroid hormones. Thyroid hormones are essential for the function of every cell in the body. They help regulate growth and the rate of chemical reactions (metabolism) in the body. The two most important thyroid hormones are thyroxine (t4) and triiodothyronine (T3). (12 Dec 1998) |
| receptors, thyroid hormone | Proteins, usually found in the nucleus, that specifically bind thyroid hormones and regulate DNA transcription. These proteins, termed c-erba, are activated by hormones and cause differentiation of erythroid progenitor cells which irreversibly lose proliferative potential. Thus c-erba proteins act as growth suppressors. The c-erba proteins are encoded by at least two genes, c-erba alpha and c-erba beta. Each of these has two isoforms. Mutations in the ligand-binding domain of the beta form causes thyroid hormone resistance syndrome. (12 Dec 1998) |
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| hormone, thyroid | Chemical substance made by the thyroid gland which is located in the front of the neck. The thyroid gland uses iodine to make thyroid hormones. The two most important thyroid hormones are thyroxine (t4) and triiodothyronine (t3). (12 Dec 1998) |
| hormone, thyroid stimulating | A hormone produced by the pituitary gland (at the base of the brain) that promotes the growth of the thyroid gland (in the neck) and stimulates it to produce its thyroid hormones. Normally, the rate of thyroid hormone production is controlled by the pituitary. When there are insufficient thyroid hormones in the body for normal functioning of the cells, the pituitary releases tsh. Tsh in turn stimulates the thyroid gland to produce more thyroid hormones. In contrast, when there is excessive amount of thyroid hormones, the pituitary gland stops producing tsh. The tsh level then falls and thyroid hormone production is reduced. This mechanism maintains a relatively constant level of thyroid hormones circulating in the blood. This phenomenon is analogous to a thermostat used for temperature regulation in a room: when the temperature rises, the thermostat shuts the heater off and the room temperature falls back to normal. High levels of thyroid hormones cause the tsh level to fall, resulting in no further stimulation of the thyroid gland. In hyperthyroidism, there are continuously elevated levels of the thyroid hormones. Tsh is also known as thyrotropin. (12 Dec 1998) |
| thyroid releasing hormone | <endocrinology> Thyroid releasing hormone (TRH) is a byproduct of the hypothalamus and serves to stimulate the pituitary gland to produce thyroid stimulating hormone (TSH). TRH is produced by the hypothalamus when thyroid hormone (T3 and T4) blood levels are low. (27 Sep 1997) |
| thyroid stimulating hormone | <endocrinology> Polypeptide hormone (28 kD), secreted by the anterior pituitary gland, that activates cyclic AMP production in thyroid cells leading to production and release of the thyroid hormones (T4 and T3). T4 and T3 blood levels feedback on the pituitary gland and decrease thyroid stimulating hormone production when T3 and T4 levels are high. (27 Sep 1997) |
| thyroid-stimulating hormone | thyroid stimulating hormone |
| thyroid-stimulating hormone-releasing factor | <protein> See thyrotrophic releasing hormone. (18 Nov 1997) |
| thyroid-stimulating hormone stimulation test | TSH stimulating test, a test that measures the uptake of 131I in the thyroid gland before and after administration of thyroid-stimulating hormone; useful in distinguishing primary hyperthyroidism (increased TSH serum concentration) from secondary or tertiary hyperthyroidism (low TSH serum concentrations). (05 Mar 2000) |
| receptors, pituitary hormone-regulating hormone | Cell surface receptors that bind the hypothalamic hormones regulating pituitary cell differentiation, proliferation, and hormone synthesis and release, including the pituitary-releasing and release-inhibiting hormones. The pituitary hormone-regulating hormones are also released by cells other than hypothalamic neurons, and their receptors also occur on non-pituitary cells, especially brain neurons, where their role is less well understood. Receptors for dopamine, which is a prolactin release-inhibiting hormone as well as a common neurotransmitter, are not included here. (12 Dec 1998) |
| growth hormone inhibiting hormone | <protein> Gastrointestinal and hypothalmic peptide hormone (two forms: 14 and 28 residues), found in gastric mucosa, pancreatic islets, nerves of the gastrointestinal tract, in posterior pituitary and in the central nervous system. Inhibits gastric secretion and motility: in hypothalamus/pituitary inhibits somatotropin release. (18 Nov 1997) |
| growth hormone-regulating hormone | <endocrinology> Hypothalamic hormones that induce (somatoliberin) or inhibit (somatostatin) the release of growth hormone (somatotropin). (18 Nov 1997) |
| growth hormone-releasing hormone | <endocrinology> Peptide hormone related to the glucagon family, released from the pituitary, acts on the adenohypophysis to release growth hormone. Synonym: somatoliberin, growth hormone-releasing factor. (20 Sep 2002) |
| hormones, hormone substitutes, and hormone antagonists | A collective grouping for both naturally occurring and synthetic hormones, substitutes, and antagonists. (12 Dec 1998) |
| follicle-stimulating hormone-releasing hormone | A decapeptide of hypothalamic origin capable of accelerating pituitary secretion of follitropin. Synonym: follicle-stimulating hormone-releasing factor, follicle-stimulating hormone-releasing hormone. Origin: follicle-stimulating hormone + L. Libero, to free, + -in (05 Mar 2000) |
| luteinizing hormone/follicle-stimulating hormone-releasing factor | gonadotrophin-releasing hormone |