Thyroid-stimulating hormone
[1] It is a glycoprotein hormone produced by thyrotrope cells in the anterior pituitary gland, which regulates the endocrine function of the thyroid.
[2][3] TSH (with a half-life of about an hour) stimulates the thyroid gland to secrete the hormone thyroxine (T4), which has only a slight effect on metabolism.
[1] TSH is secreted throughout life but particularly reaches high levels during the periods of rapid growth and development, as well as in response to stress.
Somatostatin is also produced by the hypothalamus, and has an opposite effect on the pituitary production of TSH, decreasing or inhibiting its release.
In pregnancy, prolonged high concentrations of hCG can produce a transient condition termed gestational hyperthyroidism.
[citation needed] Reference ranges for TSH may vary slightly, depending on the method of analysis, and do not necessarily equate to cut-offs for diagnosing thyroid dysfunction.
[15] The National Academy of Clinical Biochemistry (NACB) stated that it expected the reference range for adults to be reduced to 0.4–2.5 μIU/mL, because research had shown that adults with an initially measured TSH level of over 2.0 μIU/mL had "an increased odds ratio of developing hypothyroidism over the [following] 20 years, especially if thyroid antibodies were elevated".
In pregnancy, TSH measurements do not seem to be a good marker for the well-known association of maternal thyroid hormone availability with offspring neurocognitive development.
[20] Synthetic recombinant human TSH alpha (rhTSHα or simply rhTSH) or thyrotropin alfa (INN) is manufactured by Genzyme Corp under the trade name Thyrogen.
[33] In this review it was found that the recombinant human thyrotropin-aided radioactive iodine appeared to lead to a greater reduction in thyroid volume at the increased risk of hypothyroidism.
[34] The first standardised purification protocol for this thyrotropic hormone was described by Charles George Lambie and Victor Trikojus, working at the University of Sydney in 1937.
