Located in the neck below the thyroid cartilage, which forms the adam's apple, or laryngeal prominence and at the same height as the cricoid cartelage, it controls how quickly a body uses energy and makes proteins.
It also controls the sensitivity of a body to other hormones. It takes part in these important processes by generating various thyroid hormones.
The two main hormones produced are firstly triiodothyronine (T3) and secondly thyroxine (T4). They regulate the metabolism rate and affect growth and function of other body systems. Both are synthesised from iodine and tyrosine.
Calcitonin, another product of the thyroid, plays an active role in so-called calcium homeostasis.
The most commonly encountered problems with the thyroid are an over-active gland, known as hyperthyroidism and hypothyroidism, an under-active gland.
Hyperthyroidism can in extreme cases lead to toxic goiters caused by excessive growth of the gland in response to no negative feedback being received.
This may either be treated via radioactive iodine being administered and taken up by the thyroid, eventually destroying at least part of it; or, if all else fails, by completely removing the thyroid gland.
Removing the thyroid will result in hypothyroidism. Typical symptoms of this condition include tiredness, abnormal weight gain, bradicardia, baldness and cold intolerance.
Hypothyroidism is usually treated with a therapy of hormone replacement. This treatment is usually required by the patient for the rest of his or her life.
Being administered and continually monitored by a physician, this treatment may take several weeks before becoming fully effective.
In conclusion, this means that it is possible to live without a thyroid gland but effects of the removal will result in a condition known as hypothyroidism, requiring life--long treatment and regular supervision by a physician.