Thyroid

In anatomy, the thyroid is the largest endocrine gland in the body. It is situated on the front side of the neck at the level of C5 and T1 vertebral bodies, just below the laryngeal prominence (Adam's apple), near the thyroid cartilage over the trachea but covered by layers of skin and muscle. The thyroid is quite large for an endocrine gland - 15-40 grams in adults- and butterfly-shaped: the wings correspond to the lobes and the body to the isthmus of the thyroid. Normally it is larger during menstruation and in pregnant women.

Causes of thyroid problems

In areas of the world where iodine - essential for the production of thyroxine - is lacking in the diet, the thyroid gland can be considerably enlarged, resulting in the swollen necks of endemic goitre.

Related Topics:
Iodine - Thyroxine - Goitre

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Thyroxine is critical to the regulation of metabolism and growth, throughout the animal kingdom. Among amphibians, for example, administering a thyroid-blocking agent such as propylthiouracil can prevent tadpoles from metamorphosing into frogs; conversely, administering thyroxine will trigger metamorphosis.

Related Topics:
Metabolism - Amphibians

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In humans, children born with thyroid hormone deficiency will not grow well, and brain development can be severely impaired, in the condition referred to as cretinism. Newborn children in many developed countries are now routinely tested for thyroid hormone deficiency; this is done by analysis of a small drop of blood from the child (usually, the blood also is tested for phenylketonuria and several other metabolic diseases of genetic etiology). Children with thyroid hormone deficiency are easily treated by supplementation with synthetic thyroxine, which enables them to grow and develop normally.

Related Topics:
Cretinism - Phenylketonuria

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Because of the thyroid's selective uptake and extreme concentration of what is actually a quite rare element, it is extremely sensitive to the effects of various radioactive isotopes of iodine produced by nuclear fission. In the event of large accidental releases of such material into the environment, the uptake of radioactive iodine by the thyroid can, in theory, be blocked by saturating the uptake mechanism with a large surplus of non-radioactive iodine, taken in the form of potassium iodide tablets. While biological researchers making compounds labelled with iodine isotopes do this, in the wider world such preventive measures are usually not stockpiled before an accident, nor are they distributed adequately afterward - one consequence of the Chernobyl disaster was an increase in thyroid cancers in the years following the accident. http://news.bbc.co.uk/hi/english/sci/tech/newsid_1319000/1319386.stm

Related Topics:
Isotope - Nuclear fission - Non-radioactive iodine - Chernobyl disaster - Cancer

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Iodised salt is a very cheap and easy way of adding iodine to the diet.

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