Thyroid Gland

Thyroid Gland



The thyroid gland is the biggest gland in the neck. It is situated in the
anterior (front) neck below the skin and muscle layers. The thyroid gland takes the shape of a butterfly with the two wings being
represented by the left and right thyroid lobes which wrap around the
trachea. The sole function of the thyroid is to make thyroid hormone.

The function of the Thyroid is to regulate the body's metabolism.

Thyroid Essentials

• The thyroid regulates your metabolism.
  
• The two main thyroid hormones are T3 and T4.
  
• Thyroid disorders are common, and they include goiters, hyperthyroidism, and hypothyroidism.
  

The thyroid’s main role in the endocrine system is to regulate your
metabolism, which is your body’s ability to break down food and convert
it to energy. Food essentially fuels our bodies, and our bodies each
“burn” that fuel at different rates. This is why you often hear about
some people having “fast” metabolism and others having “slow”
metabolism.

The thyroid keeps your metabolism under control through the action of
thyroid hormone, which it makes by extracting iodine from the blood and
incorporating it into thyroid hormones. Thyroid cells are unique in that
they are highly specialized to absorb and use iodine. Every other cell
depends on the thyroid to manage its metabolism.

The pituitary gland and hypothalamus both control the thyroid. When thyroid
hormone levels drop too low, the hypothalamus secretes TSH Releasing
Hormone (TRH), which alerts the pituitary to produce thyroid stimulating
hormone (TSH). The thyroid responds to this chain of events by
producing more hormones. To learn more, read our article about

Anatomy of the Thyroid




Derived from the Greek word meaning shield,
the thyroid is a butterfly-shaped gland located in front of the
windpipe (called the trachea) and just below the larynx or Adam’s apple
in the neck. It is comprised of two halves, known as lobes, which are
attached by a band of thyroid tissue called the isthmus.

During development , the thyroid is actually located in the back of the tongue
and has to migrate to the front of the neck before birth. There are rare
instances when the thyroid migrates too far or too little. There are
even cases when the thyroid remains in the back of the tongue—this is
known as lingual thyroid.
Hormones of the Thyroid

The two main hormones the thyroid produces and releases are
T3(tri-iodothyronine) and T4 (thyroxine). A thyroid that is functioning
normally produces approximately 80% T4 and about 20% T3, though T3 is
the stronger of the pair.

To a lesser extent, the thyroid also produces calcitonin, which helps control blood calcium levels.


Diseases and Disorders of the Thyroid

There are many diseases and disorders associated with the thyroid. They can
develop at any age and can result from a variety of causes—injury,
disease, or dietary deficiency, for instance. But in most cases, they
can be traced to the following problems:

• Too much or too little thyroid hormone (hyperthyroidism and hypothyroidism, respectively).
  
• Abnormal thyroid growth
  
• Nodules or lumps within the thyroid
  
• Thyroid cancer
  

Common Thyroid Problems

• Goiters A thyroid goiter is a dramatic enlargement of the thyroid gland. Goiters
  are often removed because of cosmetic reasons or, more commonly, because
  they compress other vital structures of the neck including the trachea
  and the esophagus making breathing and swallowing difficult. Sometimes
  goiters will actually grow into the chest where they can cause trouble
  as well. Several nice x-rays will help explain all types of thyroid
  goiter problems.
  
• Thyroid Cancer Thyroid cancer is a fairly common malignancy, however, the vast majority have
  excellent long term survival. We now include a separate page on the
  characteristics of each type of thyroid cancer and its typical
  treatment, follow-up, and prognosis. Over 30 pages thyroid cancer.
  
• Solitary Thyroid Nodules There are several characteristics of solitary nodules of the thyroid
  which make them suspicious for malignancy. Although as many as 50% of
  the population will have a nodule somewhere in their thyroid, the
  overwhelming majority of these are benign. Occasionally, thyroid nodules
  can take on characteristics of malignancy and require either a needle
  biopsy or surgical excision. Now includes risks of radiation exposure and the role of Needle Biopsy for evaluating a thyroid nodule. Also a new page on the role of ultrasound in diagnosing thyroid nodules and masses.
  
• Hyperthyroidism Hyperthyroidism means too much thyroid hormone. Current methods used
  for treating a hyperthyroid patient are radioactive iodine, anti-thyroid
  drugs, or surgery. Each method has advantages and disadvantages and is
  selected for individual patients. Many times the situation will suggest
  that all three methods are appropriate, while other circumstances will
  dictate a single best therapeutic option. Surgery is the least common
  treatment selected for hyperthyroidism. The different causes of
  hyperthyroidism are covered in detail.
  
• Hypothyroidism Hypothyroidism means too little thyroid hormone and is a common
  problem. In fact, hypothyroidism is often present for a number of years
  before it is recognized and treated. There are several common causes,
  each of which are covered in detail. Hypothyroidism can even be
  associated with pregnancy. Treatment for all types of hypothyroidism is
  usually straightforward.
  
• Thyroiditis Thyroiditis is an inflammatory process ongoing within the thyroid gland.
  Thyroiditis can present with a number of symptoms such as fever and
  pain, but it can also present as subtle findings of hypo or
  hyper-thyroidism. There are a number of causes, some more common than
  others. Each is covered on this site.