What is thyroid gland?

The thyroid is a butterfly-shaped gland the size of a small mandarin, and is located in the neck area, right in front of the trachea. Just like all our organs and tissues, the thyroid gland has a very specific function, which plays an important role in the evolution and survival or our organism. It can be compared to a conductor and controls all the metabolic processes and energy outputs of the human body.

The thyroid gland’s main function is to produce two important hormones, which act on all our cells by controlling their metabolism and energy expenditure. The two hormones are T4 (thyroxine), produced in big quantities, and T3 (triiodothyronine), produced in very small quantities. T4 is a prohormone that is hardly active, and is transformed by specific cells into the active T3 hormone. Thyroid hormones have many different roles:

  • They control our basic metabolism
  • They ensure protein syntheses
  • They act on some cells by increasing their sensitivity to certain hormones called catecholamines (epinephrine and norepinephrine).

The main component of thyroid hormones is iodine. This is a mineral that is crucial for the normal growth of our body and our survival. In case of chronic lack of or excess of iodine, a disruption in the functioning of the thyroid gland may occur, leading to important consequences on the rest of the body.

People are generally familiar with the thyroid gland due to the association of two main pathologies – hyperthyroidism and hypothyroidism.

In the case of an increased production of T4 and T3, patients will experience an increase of their metabolic rate, along with all the associated symptoms of hyperthyroidism including weight loss, nervousness, jitters, sleep troubles and heat flashes. Conversely, if not enough T4 and T3 hormones are produced, patients may suffer from hypothyroidism along with lack of energy, depression and hypothermia.

The gland’s function is tightly regulated by a small structure located inside the brain called the pituitary gland. This gland produces another specific hormone called TSH that directly controls the production of T4 and T3 hormones. In case of medical disorder, TSH dosage is a frequent test requested by the doctor since it allows them to evaluate the correct functioning of the thyroid gland. This is an easy way to detect any case of hyper- or hypothyroidism.