The Thyroid Gland and Thyroid Hormone The thyroid gland is a butterfly shaped gland that is located over
trachea (wind pipe) just below larynx (voice box). The thyroid gland plays a very important role in most all metabolic processes of body. The thyroid gland with its thyroid hormone is responsible for regulating metabolism.
How Thyroid Hormone is Made
The hypothalamus, often referred to as body's "thermostat" is responsible for making sure thyroid blood levels are normal. When hypothalamus notices thyroid blood levels decreasing it releases TRH (thyroid releasing hormone). The TRH then signals pituitary gland to release TSH (thyroid stimulating hormone). TSH stimulates thyroid gland to begin producing thyroid hormone.
When body's levels of thyroid hormone become normal and body is functioning normally pituitary gland will cease its release of TSH and process stops until hypothalamus notices thyroid hormone levels decreasing again.
Hypothyroidism
Hypothyroidism is caused by insufficient production or absorption of thyroid hormone that causes abnormally low blood thyroid hormone levels. This problem with thyroid gland is usually brought about as a result of iodine insufficiency, a tumor, a damaged thyroid gland, or vitamin deficiencies. This type of hypothyroidism is called "primary hypothyroidism". Hypothyroidism can also be a result of pituitary gland and/or hypothalamus failing to function properly. This type of hypothyroidism is called "secondary hypothyroidism".
Low thyroid hormone levels may not only make you feel old, they can propel you into conditions and diseases associated with aging. Low levels of T4 can be responsible for weight gain, since T4 plays a role in controlling body's metabolism. The changes that are brought about as a result of aging process such as changes in fat to muscle ratio and shrinkage of organs can also be caused by a lack of thyroid hormone. A decrease in amount of lean body mass can in turn interfere with activity of an enzyme that converts thyroxine (T4) into triodothyronine (T3). T3 is about 5 times more potent than T4.
Adequate levels of thyroid hormone are needed to regulate blood sugar, so a deficiency of thyroid hormone can lead to mature-onset diabetes. Low levels of thyroid hormone can also greatly increase risk of cardiovascular disease due to an increase in levels of cholesterol and triglycerides and may cause high blood pressure. Also, iodine is essential to proper functioning of thyroid gland, several studies that have been done have shown a correlation between low iodine levels and an increased risk of cancer.
Hypothyroidism is a fairly common problem. About 1 in 10 women and 1 in 20 men over age of 50 will develop some symptoms of hypothyroidism. Thyroid hormone production decreases as we age, however usual age related decrease in thyroid hormone production is not considered true hypothyroidism. Hypothyroidism is diagnosed when thyroid hormone level drops below what is considered "normal for age".
The general opinion of many in medical community has been that drop that occurs in hormone levels is a normal part of aging process and replacement is not necessary. Although some of their aging patients are having clear symptoms of insufficient thyroid hormone levels, some physicians refuse to place these ailing patients on thyroid medication because they consider their ailing condition a normal part of aging process. These patients are missing out on thyroid replacement therapy that should alleviate or improve most, if not all their symptoms. Thankfully this negative opinion is slowly changing.
