Hypothyroidism

Hypothyroidism

Hypothyroidism is a condition in which the thyroid gland fails to produce enough thyroid hormone. This gland is located in the lower part of the neck, below the Adam's apple. The gland wraps around the windpipe (trachea) and has a shape that is similar to a butterfly - formed by two wings (lobes) and attached by a middle part (isthmus). Thyroid hormones are necessary for normal metabolism, growth, and development. The main functions of thyroid hormones include regulation of basal metabolic rate (a measure of the rate of metabolism), increased heat production, and increased glucose utilization which the body is using high level of the simple sugar (monosaccharide) that serves as the chief source of energy in the body.

The synthesis of the iodine-containing thyroid hormones thyroxine (T4) and triiodothyronine (T3) is controlled by the hypothalamic, pituitary, and thyroid. The hypothalamus synthesizes and releases the peptide thyrotropin releasing hormone (TRH) that travels through a portal blood system to the anterior pituitary, where it stimulates pituitary thyrotropins to produce and release the peptide thyrotropin (thyroid- stimulating hormone; TSH). Thyrotropin enters the systemic circulation, where it travels to and stimulates the thyroid gland, to produce T4 and T3. The thyroid hormones then act through a powerful negative feedback mechanism at the levels of the hypothalamus and pituitary to inhibit further release of TRH and TSH. This allows for tight regulation of thyroid hormone production (Nov.2005).

Hypothyroidism may be caused by or is associated with many risk factors. Some of the risk factors are Iodine deficiency which mostly is available from the diet in foods such as seafood, bread, and salt; autoimmune thyroiditis which is a progressive disease of the thyroid gland characterized by the presence of antibodies directed against the thyroid, and by infiltration of the thyroid gland by lymphocytes (June 2006), and subclinical hypothyroidism which is an illness that stays below the surface of clinical detection. There are some tests and exams that are made to help diagnose hypothyroidism. A physical examination reveals delayed relaxation of muscles during tests of reflexes. Other findings may include pale, yellow skin, thin and brittle hair, coarse facial features, brittle nails, firm swelling of the arms and legs, and mental slowing. Vital signs may show slow heart rate, low blood pressure, and low temperature. Laboratory tests to determine thyroid function include: T4 test (low), T3 test, and Serum TSH which is showing high in primary hypothyroidism, ...