How amazing is the thyroid!

It governs the functioning of almost all our organs. In particular, it regulates metabolism as well as growth processes, and cooperates to properly develop the central nervous system. It produces two hormones: thyroxine, also called T4, and triiodothyronine, known as T3. They are regulated by a hormone produced in the pituitary gland (hypophysis): TSH, that is Thyroid Stimulating Hormone. We are talking about the thyroid, the endocrine gland that is fundamental to our health and well-being. It is placed under the larynx, in front of the trachea.

And it is so small…

The thyroid has a bizarre shape recalling a butterfly whereby the two lobes correspond to the wings, joined by a central body called isthmus. It is small: each lobe has a length of 4-7 cm, a width of 1-3 cm, a thickness of 1-2 cm, whereas the isthmus is smaller than 5 mm. It is also light: it reaches 20 g in adults. Its weight varies according to age, body weight, sex, type of diet and is influenced by environmental factors as well.
Its size undergoes variations in different life stages: puberty, pregnancy, breast-feeding, menopause and ageing. Usually, sizes are larger in men.

How it works

The hormones produced and synthesized by the thyroid are stored inside the gland in structures called thyroid follicles from where they are released into the blood system which carries them all over the body and makes them available for different functions. If the quantity of hormones released into the blood system is sufficient, the thyroid blocks their production, starting it again when the level drops.


The system self-adjusts in order to reach T3 and T4 values according to the body needs.


Iodine is the key element for the production of thyroid hormones. Food and water are the main natural sources of iodine, which amount depends on concentrations in soil. Iodine gets absorbed in the intestine and released in bloodstream, to then reach the thyroid: the only organ capable of storing iodine.

For further information, please visit the Ministry of Health site