What Does Thyroid Hormone Do?

Thyroid hormones are essential hormones produced in the thyroid gland located in the neck. They play a vital role in regulating the body’s metabolism, and their malfunction can lead to a variety of problems. In this article, we will explore what thyroid hormones do, how they function, the different types of thyroid hormones, their function in the body, and disorders that result from their malfunction.


The thyroid gland produces the hormone thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body’s metabolism. These hormones help to control many bodily functions- including heart rate, body weight, and temperature regulation. The thyroid gland is present in the neck and is responsible for producing and releasing these hormones.

The Role of Thyroid Hormones in the Body

Thyroid hormones affect almost every cell in the body, and their main function is to help regulate metabolism. This includes helping to maintain body temperature, heart rate, and metabolism. In addition to these roles, thyroid hormones also play important roles in the development of the brain, bones, and reproductive organs.

Types of Thyroid Hormones

There are two main types of thyroid hormones, thyroxine (T4) and triiodothyronine (T3). T4 is produced in greater quantities than T3, but T3 is more potent.

Thyroxine (T4)

As mentioned before, T4 is produced in greater quantities than T3. It is processed by the body into T3, which is the more active form of thyroid hormone. T4 is produced by the thyroid gland and is released into the bloodstream, where it is transported throughout the body.

Triiodothyronine (T3)

T3 is the more active form of thyroid hormone and is produced in smaller quantities than T4. It is created when T4 is converted by the body’s cells. T3 plays a vital role in regulating metabolism, and its malfunction can lead to grave consequences.

Function of Thyroid Hormones

The essential function of thyroid hormones is to help regulate metabolism. This includes energy expenditure, digestion, and even mental functions. Some of the specific functions of thyroid hormones are as follow:

Metabolism Regulation:

Thyroid hormones help control the pace of the body’s metabolism. Proper regulation of metabolism ensures that the body can convert food into energy and carry out all necessary bodily functions.

Brain Development:

T3 thyroid hormone is required for the development of the brain. Its deficiency in early stages of life can result in mental retardation and other developmental problems.

Bone Development:

Thyroid hormones play an essential role in the development and maintenance of bones. A deficiency of thyroid hormones can lead to osteoporosis in women and fractures.

Regulation of Body Temperature:

Thyroid hormones also control the body’s temperature regulation mechanism. An underactive thyroid gland can cause the body’s temperature to drop, which results in feeling cold.

Disorders related to Thyroid Hormones

There are a few different types of disorders that are related to thyroid hormones, which can lead to severe consequences. Some of the common thyroid hormone disorders include


Hyperthyroidism occurs when the thyroid gland produces too much hormone resulting in an increased metabolism of the body. Symptoms of hyperthyroidism include weight loss, rapid heartbeat, anxiety, and heightened energy levels.


Hypothyroidism is the opposite of hyperthyroidism and is characterized by too little thyroid hormone being produced. This results in a sluggish metabolism, causing fatigue, weight gain, and many other symptoms.


Goitre is a swollen thyroid gland that is usually the result of an iodine deficiency.

Thyroid Cancer:

Thyroid cancer can occur when abnormal cells begin to grow in the thyroid gland.


Thyroid hormones play a vital role in the development and functioning of the body’s basic systems. Their proper functioning is essential in maintaining the body’s metabolic balance, temperature, brain development, and other key bodily functions. Any malfunction in the thyroid gland’s ability to regulate hormone production can result in a variety of serious problems.


  • Ahmed, R. A., et al. “Thyroid gland: overview, embrogenesis and pathology.” Journal of embryology and Histology 1 (2015): 1-6
  • Chaker, Layal, et al. “Thyroid function and risk of type 2 diabetes.” Jama 324.3 (2020): 229-238.
  • Biondi, Bernadette, et al. “Subclinical hypothyroidism.” Endocrine reviews 40.3 (2019): 789-824.


  • What is the function of thyroid hormones?
    Thyroid hormones help regulate metabolism in the body. They play a vital role in body temperature regulation, proper functioning of the brain, and other basic bodily functions.
  • What happens when a person has hypothyroidism?
    When a person has hypothyroidism, the thyroid gland fails to produce enough thyroid hormone, resulting in weight gain, fatigue, and other symptoms.
  • What factors can cause goitre or thyroid cancer?
    Goitre can result from iodine deficiency, inflammation, drugs, or genetic abnormalities. Thyroid cancer can be caused by the abnormal growth of cells in the thyroid gland.

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