The thyroid gland is a butterfly shaped gland in the neck. As it also looks like a shield, it was given the name “thyroid” which means “shield-like” in Greek. It weighs about 14 to 20 grams. The only function of the thyroid gland is to make hormones.
What are the hormones made by the thyroid gland?
It makes the hormone thyroxine and small amounts of two other hormones: triiodothyronine and calcitonin. Thyroxine (also called T4) is a key hormone as it regulates a very large number of things in your body. These include energy levels, weight, hair and skin health, menstrual cycles, fertility etc. Thyroxine is essential for life.
Triiodothyronine, also called T3, is more active than T4. Although the thyroid gland makes small amounts of T3, most of it is made in other parts of the body such as the liver and kidney. T3 is formed by removing a molecule of iodine from the T4 hormone.
The thyroid also makes a hormone called calcitonin, which plays a very small role in regulating calcium metabolism. However, the exact function of this hormone is still unclear.
What is Hypothyroidism and Hyperthyroidism?
Low levels of thyroxine lead to a condition called hypothyroidism, where the thyroid gland is under-active. High levels lead to the opposite condition: hyperthyroidism, or an over-active thyroid gland. You can read more about these conditions in the next 2 sections: hypothyroidism and hyperthyroidism.
What are thyroid “nodules”?
Sometimes lumps form inside the thyroid gland. They are called thyroid nodules. In the majority of cases, they are usually an overgrowth of normal thyroid cells and are therefore harmless. In fact, almost all of us will have small thyroid nodules! However, rarely some nodules have abnormal cells and can be cancerous. Fortunately this is rare.
What is a “goiter” ?
In some people, the thyroid gland changes shape and becomes larger than normal. The whole gland is overall bigger. The medical term for this is “goiter” and there are different types. When nodules of different size form in the gland, it is called multi-nodular goiter.