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According to the American Thyroid Association, millions of Americans (especially women) suffer from a thyroid disorder, and many of them dont even know it. In fact, thyroid disorders occur much more often than even many doctors realize. The butterfly-shaped thyroid is in the neck, its two wings wrapped around the windpipe just below the Adams apple. This vitally important gland normally weighs less than an ounce, but it can have an enormous impact on your health. Think of it as your bodys metabolism regulator. It does the job by releasing two hormones, most of which is the iodine-containing hormone thyroxine. The hormones help regulate your heartbeat, body temperature, the smooth working of your muscles, how quickly you burn calories, how swiftly food moves through your digestive tract and more. Normally, the thyroid doles out just the right amount of hormone to keep these processes humming smoothly.
But in some cases it may become overactive and pump out too much hormone called hyperthyroidism. And on the other hand it may slow down and produce too little hormone called hypothyroidism. Most thyroid problems-involving overactive or underactive glands-are caused by an autoimmune reaction. Normally the immune system functions to defend the body from invading microbes. In an autoimmune reaction, however, the immune system turns against the body itself and goes on the attack. In graves disease the antibodies attach to the thyroid receptors and stimulate the thyroid to produce excessive amounts of thyroid hormones.
In both cases serious imbalances in the bodys energy regulation system occur. The good news is that both kinds of thyroid problems respond well to treatment after they are diagnosed. Normally the thyroid gland is located in the front of the neck just below the Adams apple (Bayliss, 1982). This butterfly-shaped gland located at the base of your neck plays a role in your bodys metabolism. By releasing thyroid hormones, the thyroid actually regulates how your body uses fuel (Morgan 1996). The thyroid is an endocrine gland.
Other endocrine glands include the pituitary gland, pancreas, ovaries in women and testes in men, the adrenal glands, and the parathyroid glands. The thyroid manufactures certain chemical substances (hormones) that are secreted into the bloodstream and induce an effect on cells and tissues elsewhere in the body (Bayliss 1982). The thyroid makes two hormones- thyroxine, which because this chemical compound contains four iodine atoms is often called T4, and triiodothyronine which contains three iodine atoms thus calledT3 (Korte 1994). Both are secreted into the bloodstream and carried throughout the body. In many respects these thyroid hormones can be likened in their action to the speed control on a record player. They regulate the metabolic activity of all body cells and tissues. Too little thyroid hormone means that the body cells work at too slow a rate.
The result is much the same as playing a 45r.p.m. record at 331/3 r.p.m.; it is slowed and sluggish. By contrast too much hormone induces the cells to work too fast, like playing a 45 r.p.m. record at 63 r.p.m. and the result is the chipmunk effect (Epps 1995). Although the two thyroid hormones influence the proper working of all body cells, their effect is particularly evident in certain functions (Foley 1993).
For example growth and development, both physical and mental, depend upon the presence of an adequate amount of thyroxine. Without thyroxine a tadpole will not metamorphose into a frog, and without thyroxine a newborn baby will not grow properly nor will its brain develop properly. Thyroxine regulates the rate of oxygen consumption, which is another way of saying it controls the speed of activity of body cells(Morgan 1996). The secretory activity of the thyroid gland is regulated by the pituitary glands secretion of thyroid-stimulating hormone (TSH or thyrotrophin). The pituitary gland is the size of a grape and lies at the base of the brain. It secretes many different hormones including the TSH.
This hormone passes into the bloodstream and activates the thyroid gland to secrete more T4 and T3 (Thibodeau1992). As a result of this stimulation of the thyroid cells, the level of T4 and T3 in the bloodstream rises; the pituitary cells that secrete TSH sense this and the output of thyroid-stimulating hormone is reduced (Morgan 1996). This feedback control is similar to a thermostat that senses when the temperature in a house has risen to the required degree then turns off the furnace so the heat production is stopped or reduced. Vise versa, when the blood levels of T4 and T3 fall below a certain point, the TSH-secreting cells of the pituitary gland recognize this, and produce more TSH. This activates the thyroid cells to increase their output of T4 and T3 just as when rooms temperature falls below a certain point the thermostat activates the furnace to produce more heat (Bayliss 1992). Some diseases are specific or particular to the thyroid gland and do not, indeed cannot, occur elsewhere in the body.
For example overactivity of the gland and underactivity are, in the symptoms produced, diseases only associated to the thyroid (Thibodeau 1992). Certain other disorders such as acute or subacute inflammation (thyroiditis) and cancers are not so specific to the thyroid because inflammation or malignant change occurs in other organs (Epps 1995). Hyperthyroidism, also known as thyrotoxicosis, is a clinical state in which increased amounts of the two thyroid hormones thyrocine (T4) and triiodothyronine (T3) are usually present in the bloodstream. Sometimes only the T3 level is raised so called T3 toxicosis. Causes of Hyperthyroidism (Graves disease) (Bayliss 1992). The causes of hyperthyroidism are many but in practice 99% of cases are caused by increased secretion of hormones from a gland that is being overstimulated by thyroid-stimulating antibodies (Graves disease or diffuse toxic goiter) (Korte 1994). The commonest cause of hyperthyroidism is Graves disease.
Because all the thyroid cells are made overactive by stimulating antibodies circulating in the bloodstream, the whole gland is hyperactive, and this is shown by a radioactive isotope scan in which the isotope is found uniformly distributed throughout both lobes (Epps 1995). The gland is usually symmetrically enlarged to a moderate degree although it may range from being normal in size to visually obvious enlargement. Certain changes often occur in the eyes of a patient with this primary hyperthyroidism (Graves disease) (Foley 1993). Thyrotoxicosis due to Graves disease occurs ten times more in woman than in men and the reason for this is unknown. It tends to run in families and those with a particular constitutional body cell type (HLA B8-DRW3) seem most vulnerable. What triggers off the disease is unknown. In some instances Graves disease seems to follow an emotional upset but it has not proved possible to establish scientific proof of such a cause and effect relationship (Morgan 1996).
Tiredness is usually the first symptom of Graves disease, to be followed by weight loss, palpitations of the heart or consciousness of the hearts action, nervousness, apprehension or irritability and increased sweating (Foley1993). The patient feels hot all the time and is uncomfortable in warm weather. There is often generalized itching of the skin. The eye complications are the first and most obvious manifestation of Graves disease (Bayliss 1996). Progressively patients with Graves disease proceed on to a classified case of hyperthyroidism. Patients with hyperthyroidism are usually thin or show evidence of weight loss.
They are restless and anxious. It is hard for them to sit still and they fidget. Their hands are hot and when held outstretched there is a fine tremor-not a course shaking. Because it is overactive and producing too much thyroid hormone, the blood flow through the gland is increased (Thibodeau 1992). This is detected as a swishing murmur when a stethoscope is held over the front of the neck. Often the patient has starey eyes and this may be the first sign that alerts the doctor to the diagnosis (Bayliss 1982). Involvement and changes of the eyes are common in hyperthyroidism. There is a tendency for the upper eyelids to ....
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