Thyrotropic hormone from porcine pituitary can be used as a NCTC-135 medium supplement for isolating the thyroid cells which in turn is used for studying the impact of retinoids on non-transformed cells like thyrocytes. The product can also be used in cell proliferation experiment for studying the impact of increased IGF binding proteins 1 level on the function and growth of the thyroid gland in transgenic mice.
Definition
A hormone secreted by the anterior lobe of the pituitary gland. It increases the rate of removal of iodine from the blood by the thyroid gland, synthesis of the thyroid hormone, and its release into the bloodstream. The thyrotropic hormone is a protein with a low molecular weight (about 10,000) that contains some carbohydrate.
Indications
TSH, or thyrotropin, is a glycosylated protein of two
subunits, and . TSH stimulates the thyroid gland to
produce thyroid hormones. Deficiencies are treated by
giving thyroxine itself rather than TSH, but TSH is
available for diagnostic purposes to differentiate between
pituitary and thyroid gland failure as causes of
hypothyroidism.
Trademarks
Thyrotrophin is INN and BAN.
Allgemeine Beschreibung
The thyrotropic hormone, also called thyrotropin and thyroidstimulatinghormone (TSH), is a glycoprotein consisting oftwo polypeptide chains. This hormone promotes productionof thyroid hormones by affecting the kinetics of the mechanismby which the thyroid concentrates iodide ions from thebloodstream, thereby promoting incorporation of the halogeninto the thyroid hormones and release of hormones by thethyroid. TSH (Thyropar) appears to be a glycoprotein (relativemolecular mass [Mr] 26,000–30,000) containing glucosamine,galactosamine, mannose, and fucose, whose homogeneityis yet to be established. It is produced by thebasophil cells of the anterior lobe of the pituitary gland.TSH enters the circulation from the pituitary, presumablytraversing cell membranes in the process. After exogenousadministration, it is widely distributed and disappears veryrapidly from circulation. Some evidence suggests that thethyroid may directly inactivate some of the TSH by an oxidationmechanism that may involve iodine. TSH thus inactivatedcan be reactivated by certain reducing agents.TSH regulates the production by the thyroid gland of thyroxine,which stimulates the metabolic rate. Thyroxinefeedback mechanisms regulate the production of TSH bythe pituitary gland.
Biochem/physiol Actions
Two-chain glycoprotein hormone. The α-chain is not active, biological specificity attributed rather to the β-chain. Activates adenylate cyclase in the thyroid gland, stimulating iodine uptake, thyroxine synthesis and release. Goitrogenic.
Clinical Use
Recombinant form of human thyroidstimulating hormone (rhTSH). Used
diagnostically for serum thyroglobulin
testing.
Clinical Use
TSH levels are measured as part of a thyroid function
test in patients suspected of hyperthyroidism and hypothyroidism as the simplest and most sensitive indicator.
Primary hypothyroidism/hypothyroidism is characterized by a high/low serum TSH concentration and a
low/high serum free T4 concentration. Subclinical
hypothyroidism/hypothyroidism is defined biochemically as a normal free T4 concentration in the presence
of an increased/decreased TSH concentration. Central
hypothyroidism is characterized by a low serum T4 concentration and a low or normal serum TSH concentration,
whereas TSH-secreting pituitary adenomas may lead to the development of hyperthyroidism through a condition
called the syndrome of the inappropriate secretion of TSH
(SITSH). Recombinant human TSH is used in the follow up of patients with thyroid cancer to ablate the thyroid
remnant following thyroid cancer surgery, and to obtain
reliable diagnostic test results for the recurrence of differentiated thyroid cancer.
Veterinary Drugs and Treatments
The labeled indications for the formerly available veterinary product
Dermathycin? (Mallinckrodt) was for “the treatment of acanthosis
nigricans and for temporary supportive therapy in hypothyroidism
in dogs.” In actuality however, TSH is used in veterinary
medicine principally as a diagnostic agent in the TSH stimulation
test to diagnose primary hypothyroidism.
