The thyroid gland is located immediately below the larynx on each side of and anterior to the trachea. It is one of the largest of the endocrine glands, normally weighing 15 to 20 grams in adults. The thyroid secretes two major hormones, thyroxine and triiodothyronine, commonly called T4 and T3. Both of these hormones profoundly increase the metabolic rate of the body. Thyroid secretion is controlled primarily by thyroid‐ stimulating hormone (TSH) secreted by the anterior pituitary gland.
About 93 per cent of the metabolically active hormones secreted by the thyroid gland are thyroxine, and 7 per cent triiodothyronine. Thyroxine is eventually converted to triiodothyronine in the tissues. Triiodothyronine is about four times as potent as thyroxine, but it is present in the blood in much smaller quantities and persists for a much shorter time than does thyroxine.
The primary function of the thyroid gland is the secretion of thyroid hormones. Thyroid gland contains the parafollicular C cells which are important for calcium metabolism.
Promotes normal growth & development & regulates energy & heat production.
Especially in the early life in the first one year because it’s deficiency will lead to mental retardation, so early detection of hypothyroidism in infancy & during birth is very crucial… when they treated we can save them from mental retardation & developmental retard at long term… so now a day’s different parts screen every day for the thyroid stimulating hormone (TSH) to find & diagnose paranodular tissue (PNT) with cretinism & congenital hypothyroidism.
So Thyroid hormone is essential for growth & mental health
Physiology or the action of thyroid hormone:
To prevent the delay in growth &mental & physical retardation so pnt with hypothyroid will have mental & physical retardation. So it is important in fetal brain and skeletal maturation.
Interesting Questions about Thyroid:
Hyperthyroidism makes the body speed up. It occurs when there is too much thyroid hormone in the blood (“hyper” means “too much”). Nearly 10 times more frequent in women, it affects about 2% of all women in the United States.
The most common cause of hyperthyroidism, Graves’ disease, is caused by problems with the immune system and tends to run in families. It affects at least 2.5 million Americans, including Olympic athlete Gail Devers who won a gold medal in track after being diagnosed with and treated for Graves’ disease.
- fast heart rate
- increased perspiration
- muscle weakness
- trembling hands
- weight loss
- hair loss
- skin changes
- increased frequency of bowel movements
- decreased menstrual flow and less frequent menstrual flow
- eyes that seem to be popping out of their sockets.
The symptoms of hyperthyroidism rarely occur all at once. However, if you have more than one of these symptoms, and they continue for some time, you should see your doctor.
Thyroiditis is an inflammation of the thyroid gland. Thyroiditis can cause either hyperthyroidism or hypothyroidism, or one followed by the other. It can also cause a goiter, an abnormal swelling in the neck due to an enlarged thyroid. It affects about 12 million people in the United States.
Thyroiditis is the most common cause of hypothyroidism. When patients with thyroiditis have any symptoms, they are usually the symptoms of hypothyroidism. It is also common to have an enlarged thyroid that may shrink over time.
The type of thyroiditis seen most often is Hashimoto’s thyroiditis, a painless disease of the immune system that runs in families. Hashimoto’s thyroiditis affects about 5% of the adult population, increasing particularly in women as they age.
Another form of thyroiditis affects women of childbearing age. Postpartum thyroiditis occurs in 5%-9% of women soon after giving birth and is usually a temporary condition.
Viral and bacterial infections can also cause thyroiditis.
There are several different causes of hyperthyroidism:
- The entire thyroid gland may be overactive, producing too much hormone. Doctors call this problem diffuse toxic goiter, or Graves’ disease.
- One or more lumps (also called nodules) in the gland may be overactive. One such lump is called a toxic autonomously functioning thyroid nodule, and several lumps are called a toxic multi-nodular goiter.
- The gland may be inflamed, a condition called thyroiditis. It can release the thyroid hormone that was stored in the gland, causing hyperthyroidism that lasts for a few weeks or months.
- Some patients may take more thyroid hormone pills than needed or prescribed.
- Some drugs, such as Quadrinal®, amiodarone (Cordarone®), and Lugol’s solution, contain large amounts of iodine, a chemical the thyroid uses to produce its hormones, and may cause the thyroid to produce too much hormone.
® Quadrinal is a registered trademark of Knoll Pharmaceutical.
® Cordarone is a registered trademark of Wyeth Labs.
Have more questions? Need more answers? Check our Full Thyroid FAQ
Effects of Thyroid Hormone:
- Inotropic and chronotropic effects on heart so there will be increase in heart rate & the contraction of heart will be increase by pnt may develop heart failure
- Increase in sensitivity & irritability
- Increase gut motility so pnt will have diarrhea
- Increase in basal metabolic rate
- So Pnts with hyperthyroid may lose weight because there is increase in metabolic rate & because of diarrhea.
- Increases sensitivity to catecholamines
- Increase bone turnover
- Increase in serum glucose, decrease in serum cholesterol.
Physiology of Thyroid Gland:
The basic physiological function of thyroid gland is to secrete predominantly thyroxin (T4) & only a small amount of triiodothyronine (T3).
Production of thyroid hormones is regulated in normal gland by thyroid stimulating hormone (TSH) from the anterior pituitary gland, so it’s under the influence of TSH & the TSH is under the influence of TRH from the hypothalamus, SO we have a feedback mechanism to thyroid gland by TSH.
Hypothalamus>>>anterior pituitary gland>>>thyroid gland.
Approximately 75%-80% of T3 in blood is produced from deiodination of T4 to T3 & thyroid gland secretes only 20%- 25% of T3 so Most of T3 is mainly coming from T4.
T4 is converted to T3 peripherally.
T4 is primary released hormone but T3 is the active form
Because the active form (T3) is about 10 times more than T4 in the peripheral tissues & the blood>>> so the active form & the more active component is the T3.
Thyroid FAQ & Links to Related Articles
|There are four parathyroid glands that are normally having the size of a single rice grain. In some normal cases, they can be as big as the size of a pea.|
|Also called underactive thyroid, hypothyroidism is a disorder that is characterized by abnormal level of thyroid hormones in the body, which is too low.|
|The thyroid is a butterfly (pear)-shaped gland, it consists of 2 symmetrical lobes joined by a central isthmus that normally covers the 2nd & 3rd tracheal rings.|
|Congenital hypothyroidism is a thyroid gland disorder that may lead to deafness or mental retardation if left undetected.|
|Hypothyroidism can cause depression. Most people don?t realize that this feeling is depression caused by the thyroid gland not functioning as it should.|
|Papillary thyroid cancer is one of the thyroid cancer types. This type of thyroid cancer arises from the follicles in the thyroid gland.|
|The thyroid gland is located immediately below the larynx on each side of and anterior to the trachea. It is one of the largest of the endocrine glands|
|These thyroid hormones are responsible in regulating the body?s metabolism, which is how much food will be broken down into useful energy for consumption.|
|When the thyroid gland produces too much thyroid hormone, one may suffer from hyperthyroidism.|
|The thyroid stimulating hormone is produced by the pituitary gland. The thyroid stimulating hormone promotes the growth of the thyroid gland.|
|Thyroid hormones are chemical substances produced by the thyroid gland. The thyroid gland is located in the front of the neck.|
|Natural thyroid supplements are helpful as a remedy to thyroid disorders. Its natural ingredients assure one of its safeties in taking it.|
|The thyroid gland is an endocrine gland that is the primary responsible in regulating the body?s metabolism.|
|Thyroid surgery is used to treat people with thyroid problems such as thyroid cancer, thyroid nodules and hyperthyroidism.|
|Thyroid tests or thyroid function tests are done to check the thyroid function in one?s body. A doctor will be able to determine and diagnose the thyroid disorder.|
|Treatment for thyroid disorders should be done to prevent unwanted results caused by the severity of the condition. Consult a physician for more of these treatments.|
|Thyroidectomy is a surgical process wherein the whole or a part of the thyroid gland is removed. This surgical process is used to treat thyroid disorders.|
|Having an underactive thyroid is a minor problem but it seeks proper attention to avoid further health problems. Consult a physician about any thyroid problem.|
|Low thyroid, also known as hypothyroidism, is a condition where the thyroid gland is under active.|
|Following a healthy meal plan, exercise and proper medication goes hand in hand to treat hypothyroidism. Consult a physician for a more individualized plan.|
|Each thyroid cancer treatment depends on the type of thyroid cancer and the extent or stage of the thyroid cancer one is suffering from.|
|Parathyroid hormones are considered to be the most important endocrine regulator. It basically regulates the calcium and phosphorus concentration in the body.|
|Studies show that since 1925, the standard treatment for parathyroid disease is to surgically remove the parathyroid gland(s) which are overproducing parathyroid hormones.|
|Parathyroid adenoma is a small tumor of the parathyroid gland and is known to be the most common disorder of the gland.|
|Medullary thyroid cancer is one of the types of thyroid cancer. This type of thyroid cancer is more common in women than in men.|
|Most people don?t feel any symptoms. Others can just lose weight and just feel depressed for no reason at all.|
|Suppose you go in for a routine checkup and your doctor decides to test your thyroid function. You?ve experienced no thyroid disease symptoms|
|Hypothyroidism develops for over a long period of time. It?s normally from several months to even several years.|
|People who are suffering from hypothyroidism are advised to get plenty of exercise and have a balanced and healthy diet. The diet must be rich in protein and iodine.|
|Self medicating one?s thyroid disorder with hypothyroidism diet pills without proper information of the diet pill does not address the problem.|
|Hyperthyroidism is when the thyroid gland is overactive and produces too much thyroid hormones more than the body needs.|
|Hypothyroidism is one of the chronic diseases in the world. Hypothyroidism is also known as underactive thyroid; hypo means under or below normal.|
|Anaplastic thyroid cancer is a type of thyroid cancer that is rare and aggressive. It affects the thyroid gland and most especially its function.|
|Problems arise if the thyroid gland is overactive or underactive. There are three common thyroid disorders. These are hypothyroidism, hyperthyroidism and the thyroid nodules.|
Thyroid Hair Loss
|Hair loss may happen for so many reasons but it is commonly associated to thyroid problems such as hyperthyroidism and hypothyroidism.|
|Thyroid Function Tests are the different tests conducted to assess and determine the cause of an individual?s thyroid problems.|