Thyroid-stimulating hormone (also known as TSH or thyrotropin) is a hormone produced by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland.
Physiology
The hypothalamus produces thyrotropin-releasing hormone (TRH) which stimulates the pituitary gland to release TSH. TSH stimulates the thyroid gland to secrete the hormones thyroxine (T4) and triiodothyronine (T3). The production of TSH is inhibited by the production of somatostatin by the hypothalamus. T3 and T4 also inhibit TSH production and secretion, creating a regulatory negative feedback loop.
TSH consists of two subunits, the alpha and the beta subunit. The α (alpha) subunit is identical to that of human chorionic gonadotropin (HCG), luteinising hormone (LH), follicle-stimulating hormone (FSH). All four glycoprotein hormones are produced in the anterior pituitary. The β (beta) subunit is unique to TSH, and therefore determines its function.
The TSH receptor is found mainly on thyroid follicular cells. Stimulating antibodies to this receptor mimic TSH action and are found in Graves' disease.
stimulated by the arrival of thyrotropin releasing hormone (TRH) from the hypothalamus.
Synthesis and release of FSH is triggered by the arrival from the hypothalamus of gonadotropin-releasing hormone (GnRH).
The GH-secreting cells are stimulated to synthesize and release GH by the intermittent arrival of growth hormone releasing hormone (GHRH) from the hypothalamus.
The thyroid gland is located in the front of the neck attached to the lower part of the voicebox (or larynx) and to the upper part of the windpipe (or trachea).
Abnormalities of the thyroid gland are common and affect one in twenty (1 in 20) of the Canadian population.
In Hashimoto's thyroiditis, the goitre is caused by an accumulation of white blood cells and fluid (inflammation) in the thyroid gland.
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