The thyroid gland

The word thyroid comes from the Greek word thyreoeides which means “shield”, since it somewhat resembles this shape.  Leonardo da Vinci drew it as two separate glands, each one beside the larynx, like a butterfly.  The thyroid is a neuroendocrine gland located in the trachea, just below the Adam’s apple, along with the thyroid cartilage.  This glad weighs between 15 and 30 grams in an adult, and is comprised of two lobes connected by the isthmus.  The thyroids are controlled by the hypothalamus and the pituitary.

The thyroids participate in hormone production, basically Thyroxine (T4) and Triiodothyronine (T3).  These hormones are in charge of regulating primarily the body’s basal metabolism, they affect growth and degree of functioning for other body systems.  The thyroids also synthesize the hormone calcitonin which plays an important role in calcium homeostasis.

The most important hormone that the thyroids produces contains iodine, and is known as thyroxine.  It has two effects on the body: it controls energy production in the body, and is necessary for keeping the basal metabolic rate at a normal level.

Iodine is an essential component in the production process of thyroid hormones, especially for T3 and T4.

What functions do the thyroid glands have?

•  Regulate the metabolism and general body development.

Considering the most important metabolic regulations and body development, allow us to mention the following thyroid hormone actions in the body:

• They possess a thermoregulatory action
• They are necessary for proper growth and development.
• They increase oxygen consumption.
• They participate in the processes of muscular contraction and intestinal movement.
• They stimulate the synthesis and breakdown of proteins.
• They balance and regulate the mucoproteins and extracellular fluid.
• They partake in the synthesis and breakdown of fats.
• They participate in glucogen synthesis and glucose (sugar) use.
• They are basic in the formation of vitamin A, from carotenes.
• They stimulate growth and separation.
• They are indispensable for the development of the nervous system, both central and peripheral.
• They participate in dental development and growth.
• They regulate the body’s sensitivity.

They thyroids participate in practically all of the body’s organic functions, activating them and keeping them in sync, and in vital balance.

Bodily reactions to thyroid hormone deficiencies:

As mentioned before, thyroid hormones (thyroxine and triiodothyronine) have a specific effect on development and the metabolism.  When this hormone is deficient during fetal development and during the first few months following birth, the child could present severe effects.

The most prominent changes due to this lack in children:

• Deficient physical or intellectual development, which is proportional to the time that this thyroid hormone was lacking.  This effect is irreversible.

 In adults:

• The primary effect from this deficiency manifests as metabolism changes.  This effect causes changes in oxygen consumption and in the metabolism of proteins, carbohydrates, fats, and vitamins.

Hypothyroidism and hyperthyroidism

We still have not been able to identify the quantitative numbers for thyroid hormone effects.  An abnormal thyroid diagnosis is usually apparent.  Lab tests can detect thyroid dysfunction.  However, more subtle forms of thyroid dysfunction, like subclinical hypothyroidism or hyperthyroidism, present a greater challenge.

Hyperthyroidism is is characterized by very active thyroids due to a metabolic disorder whereby the excessive actions of the thyroid gland produces hypersecretion of the thyroid hormones.  This disorder’s effects cause symptoms like tachycardia, weight loss, anxiety, nervousness, and the shakes.

Hypothyroidism is associated with low activity in the thyroid glands, whose effects cause symptoms like snoring, lethargy, slow speech, changes in memory, constipation, fatigue, dry and rough skin, hair loss, sadness, fertility problems, decreased libido, impotence, irregular menstruation, unexplained weight gain, etc.

Foods for thyroid gland health

Beets and a diet rich in iodine is an advisable diet for nervous system health.  The development of thyroid tumors, which is a condition associated to a growth in the thyroids, is related to very low, or no iodine consumption.

Revised by: Dra. Loredana Lunadei on 09/27/2014

About the author