Main Role of the Thyroid Gland in the endocrine system lies in the regulation of metabolism, i.e., the body’s ability to break down food and convert it into energy.
Food essentially nourishes the body, and each of our organs uses this fuel at a different rate.
That’s why you often hear that some people have a “fast” metabolism, while others have a “slow” one.
The thyroid gland keeps your metabolism under control through the action of thyroid hormone, which it produces by extracting iodine from the blood and incorporating it into thyroid hormones.
Thyroid cells are unique in that they specialize in absorbing and using iodine. Every second cell depends on the thyroid gland to regulate its metabolism.
The pituitary gland and hypothalamus control the thyroid gland. When thyroid hormone levels drop too low, the hypothalamus releases thyrotropin-releasing hormone (TRH), which signals the pituitary gland to produce thyroid-stimulating hormone (TSH).
The thyroid gland responds to this chain of events by producing more hormones.
Anatomy of the Thyroid Gland
The thyroid gland is a butterfly- or shield-shaped gland located in front of the trachea and just below the larynx or Adam’s apple (in men) on the neck. It consists of two halves, known as lobes, which are connected by a strip of thyroid tissue called the isthmus.
During development, the thyroid gland is actually located at the back of the tongue and should migrate to the front of the neck before birth. There are rare cases when the thyroid gland migrates too far or too little. There are even cases when the thyroid gland remains at the back of the tongue — this is known as a lingual thyroid.
Thyroid Hormones
The thyroid gland produces and releases two main hormones:
T3 (triiodothyronine) and T4 (thyroxine)
A normally functioning thyroid gland produces approximately 80% T4 and about 20% T3, although T3 is the more potent of the pair.
To a lesser extent, the thyroid gland also produces calcitonin, which helps control the level of calcium in the blood.
Thyroid Diseases and Disorders
There are many diseases and disorders associated with the thyroid gland. They can develop at any age and may be caused by various factors, such as injury, illness, or dietary deficiency. But in most cases, they can be attributed to the following issues:
Some of the most common thyroid diseases:
Goiter
A goiter is a swelling in the neck. Toxic goiter is associated with hyperthyroidism, while non-toxic goiter, also known as simple or endemic goiter, is caused by iodine deficiency.
Hyperthyroidism
Hyperthyroidism is caused by an excessive amount of thyroid hormones. People with hyperthyroidism are often sensitive to heat, hyperactive, and eat excessively. A goiter is sometimes a side effect of hyperthyroidism. This occurs due to excessive stimulation of the thyroid gland and inflamed tissues, respectively.
Hypothyroidism
Hypothyroidism is a common condition characterized by a deficiency of thyroid hormones. In infants, this condition is known as cretinism. Cretinism has very serious side effects, including abnormal bone formation and intellectual disability. If you have hypothyroidism in adulthood, you may experience sensitivity to cold, poor appetite, and general lethargy. Hypothyroidism often goes unnoticed, sometimes for many years, before it is diagnosed.
Solitary Thyroid Nodules
Solitary nodules or lumps in the thyroid gland are actually quite common—it’s estimated that more than half of the population has thyroid nodules. The vast majority of nodules are benign. Typically, a fine-needle aspiration biopsy (FNAB) helps determine if a nodule is malignant.
Thyroid cancer
Thyroid cancer is quite common, although long-term survival rates are excellent. Sometimes people with thyroid cancer experience symptoms such as hoarseness, neck pain, and enlarged lymph nodes. Thyroid cancer can affect anyone at any age, although it most commonly develops in women and people over thirty.
Thyroiditis
Thyroiditis is an inflammation of the thyroid gland, which may be associated with impaired thyroid function (particularly hyperthyroidism). The inflammation can lead to the destruction of thyroid cells, causing the thyroid gland to be unable to produce enough hormones to maintain normal metabolism in the body. There are five types of thyroiditis, and the treatment for each is specific.
Doctor - Obstetrician-Gynecologist, Ultrasound Diagnostics Doctor