Thyroid gland hormones produced

TSH, or thyrotropin, is a glycosylated protein of two subunits, a and p. 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 (see Chapter 65). 

Biosynthetic defects in thyroid hormonogenesis may also result in an inability of the thyroid gland to produce sufficient hormone and may be due to inherited enzymatic deficiencies or the ingestion of natural or therapeutically administered antithyroid agents. An example in the latter category is lithium, widely used to treat psychiatric disorders and associated with the development of hypothyroidism and goiter. It is concentrated by the thyroid, where it inhibits thyroidal I uptake, incorpora-... 

Thyroid Hypofunction Hypothyroidism is the most common disorder of thyroid function. It can be divided into patients who have a failure of the thyroid gland to produce sufficient thyroid hormone (primary hypothyroidism) and patients in which pituitary or hypothalamic disease is associated with impaired TSH stimulation (central or secondary hypothyroidism). Worldwide, primary hypothyroidism is caused most often by iodine deficiency. In areas where iodine is sufficient, chronic autoimmune thyroiditis (Hashimoto s thyroiditis) accounts for most cases. Other causes include postpartum thyroiditis, surgical removal, or radioactive iodine ablation of the gland. Hypothyroidism present at birth (cretinism) is the most common preventable cause of mental retardation in the world. 

Figure 84.1 Showing a huge goiter of a femaie inhabitant aged 78 years, who lived for a long time in an iodine-deficient area in Austria. Hypothyroidism caused by iodine deficiency led to an increase in thyroid-stimulating hormone produced in the pituitary gland leading to such an enlargement of the thyroid gland.

Parathyroid Glands Small glands, usually located within the thyroid gland, which produce parathyroid hormone this hormone regulates calcium levels in the bloodstream and bones. 

Several years ago, it was discovered that the thyroid gland was also the source of a hypocalcemic hormone having effects in general opposition to those of the parathyroid hormone. This hormone is produced in mammals by the parafollicular C-ceUs and in other vertebrates by the ultimobrachial bodies (45). Originally called thyrocalcitonin, it is now referred to as calcitonin (CT). 

Thyroid autonomy appears as a solitary toxic nodule or toxic multinodular goitre. In toxic thyroid, the nodule s synthesis and secretion of thyroid hormones is autonomous from the thyroid-stimulating hormone (TSH), which is produced in the pituitary gland. Accordingly TSH is suppressed and the extranodular thyroid tissue is functionally downregulated. Thyroid autonomy occurs frequently in iodine-deficient countries, whereas it is much less common in iodine-sufficient areas. Constitu-tively activating mutations in the TSH receptor and in the Gs a protein are the major molecular aetiology of toxic thyroid nodules. 

C03-0144. The thyroid gland produces hormones that help regulate body temperature, metabolic rate, reproduction, the synthesis of red blod cells, and more. Iodine must be present in the diet for these thyroid hormones to be produced. Iodine deficiency leads to sluggishness and weight gain, and can cause severe problems in the development of a fetus. One thyroid hormone is thyroxine, whose chemical formula is... 

A trophic hormone acts on another endocrine gland to stimulate secretion of its hormone. For example, thyrotropin, or thyroid-stimulating hormone (TSH), stimulates the secretion of thyroid hormones. Adrenocorticotropin, or adrenocorticotropic hormone (ACTH), stimulates the adrenal cortex to secrete the hormone cortisol. Both trophic hormones are produced by the pituitary gland in fact, many trophic hormones are secreted by the pituitary. The pituitary gland is sometimes referred to as the "master gland" because its hormones regulate the activity of other endocrine glands. 

The thyroid gland is a butterfly-shaped structure lying over the ventral surface of the trachea just below the larynx. This gland produces two classes of hormones synthesized by two distinct cell types ... 

To understand the MOA by which the thyroid tumors are produced, the effect of pyrethrins on rat thyroid gland, thyroid hormone levels, and hepatic thyroxine UDP-glucuronosyltransferase activity was also investigated [128]. The treatment of male rats with 8,000 ppm pyrethrins, female rats with 3,000 and 8,000 ppm pyrethrins, and both sexes with phenobarbital resulted in increased thyroid gland... 

Thyroid Gland A highly vascular endocrine gland consisting of two lobes, one on either side of the trachea, joined by a narrow isthmus it produces the thyroid hormones which are concerned in regulating the metabolic rate of the body. [NIH]... 

Trace amounts of iodine are required for a healthy body. Iodine is part of the hormone thyroxin produced by the thyroid gland. Thyroid secretions control the physical and mental development of the human body. A goiter, a swelling of the thyroid gland, is caused by the lack of iodine. Adding thyroid medication and iodized salt to the diet helps prevent this disease. Radioactive iodine (1-131), with a half-life of eight days, is used to treat some diseases of the thyroid gland. 

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