Definition: What is the Thyroid?The thyroid is an endocrine gland that's essential for the body to function properly. Butterfly-shaped, it is located at the neck, under the Adam's apple. Its role is to regulate the metabolism of the body's cells. The thyroid is the root of several pathologies such as hypothyroidism, hyperthyroidism, thyroiditis, or thyroid cancer. The Function of the ThyroidThe thyroid produces thyroid hormones called thyroxine (T4), triiodothyronine (T3), and calcitonin. Their production is stimulated production is stimulated by the thyroid stimulating hormone (TSH), which is secreted by the pituitary gland. The pituitary gland constantly monitors the hormone levels and makes the decision to increase or decrease production. The thyroid hormones then circulate in the blood and enter the nucleus of the cells, resulting in the synthesis of several proteins. They make it possible to regulate cell metabolism. The thyroid manages energy expenditure, muscle energy, reflexes, weight, body temperature, blood pressure, and heart rate. It also plays a vital role in the growth and maturation of the central nervous system.Hypothyroidism and HyperthyroidismDysregulation of the thyroid gland can lead to many complications. It is estimated that every two in 100 people are affected by thyroid disease in the UK, although doctors are speculating that the rate could be higher. There are several types of diseases. When the production of hormones is insufficient, it is called hypothyroidism. This manifests itself through a slowing of the metabolism. Conversely, hyperthyroidism is too much secretion, causing an acceleration of the metabolism. Thyroiditis: Thyroid Disease There exist also many inflammations of the thyroid or thyroiditis. Some are autoimmune, such as Graves' disease, the most common cause of hyperthyroidism. There's also Hashimoto's thyroiditis, which often causes hypothyroidism. An example of a non-autoimmune thyroid disease is acute thyroiditis. Infectious, it often follows a bacterial infection with a staph or streptococcus. The cause of thyroiditis can also be treated with medication. In this case we're referring to iatrogenic thyroiditis. In rare cases, the thyroid can become cancerous. There are several forms of this. Papillary cancers are the most common (about 70%), but there is also vesicular cancer, anaplastic cancer, and spinal cord carcinoma.