Hyperthyroidism

Hyperthyroidism is a condition in which the thyroid gland makes too much thyroid hormone. The condition is often referred to as an “overactive thyroid.”
Causes, incidence, and risk factors

The thyroid gland is an important organ of the endocrine system. It is located in the front of the neck just below the voice box. The gland produces the hormones thyroxine (T4) and triiodothyronine (T3), which control the way every cell in the body uses energy. This process is called metabolism.

Hyperthyroidism occurs when the thyroid releases too much of its hormones over a short (acute) or long (chronic) period of time. Many diseases and conditions can cause this problem, including:

Hypothyroidism

Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.
Causes, incidence, and risk factors

The thyroid gland is located in the front of the neck just below the voice box (larynx). It releases hormones that control metabolism.

Hypothyroidism, or underactive thyroid, is more common in women and people over age 50.