Thyroid hormones in the context of "Thyroid disease"

Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at 114 °C (237 °F), and boils to a violet gas at 184 °C (363 °F). The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek Ιώδης, meaning 'violet'.

Iodine occurs in many oxidation states, including iodide (I), iodate (IO
₃), and the various periodate anions. As the heaviest essential mineral nutrient, iodine is required for the synthesis of thyroid hormones. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities.

Thyroid disease is a medical condition that affects the structure and/or function of the thyroid gland. The thyroid gland is located at the front of the neck and produces thyroid hormones that travel through the blood to help regulate many other organs, meaning that it is an endocrine organ. These hormones normally act in the body to regulate energy use, infant development, and childhood development.

There are five general types of thyroid disease, each with their own symptoms. A person may have one or several different types at the same time. The five groups are:

The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is a butterfly-shaped gland located in the neck below the Adam's apple. It consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the isthmus (pl.: isthmi). Microscopically, the functional unit of the thyroid gland is the spherical thyroid follicle, lined with follicular cells (thyrocytes), and occasional parafollicular cells that surround a lumen containing colloid.

The thyroid gland secretes three hormones: the two thyroid hormones – triiodothyronine (T₃) and thyroxine (T₄) – and a peptide hormone, calcitonin. The thyroid hormones influence the metabolic rate and protein synthesis and growth and development in children. Calcitonin plays a role in calcium homeostasis.

Graves' disease, also known as toxic diffuse goiter or Basedow's disease, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyroid. Signs and symptoms of hyperthyroidism may include irritability, muscle weakness, sleeping problems, a fast heartbeat, poor tolerance of heat, diarrhea and unintentional weight loss. Other symptoms may include thickening of the skin on the shins, known as pretibial myxedema, and eye bulging, a condition caused by Graves' ophthalmopathy. About 25 to 30% of people with the condition develop eye problems.

The exact cause of the disease is unclear, but symptoms are a result of antibodies binding to receptors on the thyroid, causing over-expression of thyroid hormone. Persons are more likely to be affected if they have a family member with the disease. If one monozygotic twin is affected, a 30% chance exists that the other twin will also have the disease. The onset of disease may be triggered by physical or emotional stress, infection, or giving birth. Those with other autoimmune diseases, such as type 1 diabetes and rheumatoid arthritis, are more likely to be affected. Smoking increases the risk of disease and may worsen eye problems. The disorder results from an antibody, called thyroid-stimulating immunoglobulin (TSI), that has a similar effect to thyroid stimulating hormone (TSH). These TSI antibodies cause the thyroid gland to produce excess thyroid hormones. The diagnosis may be suspected based on symptoms and confirmed with blood tests and radioiodine uptake. Typically, blood tests show a raised T₃ and T₄, low TSH, increased radioiodine uptake in all areas of the thyroid, and TSI antibodies.

Thyroiditis is the inflammation of the thyroid gland. The thyroid gland is located on the front of the neck below the laryngeal prominence, and makes hormones that control metabolism.

Thyroiditis is a group of disorders that all cause thyroidal inflammation. Symptoms, diagnosis and treatment depend on the cause of thyroiditis. Forms of thyroiditis are Hashimoto's thyroiditis, postpartum thyroiditis, subacute (de Quervain's) thyroiditis, silent thyroiditis, drug-induced thyroiditis, radiation-induced thyroiditis and acute thyroiditis.

Intracellular receptors are globular protein receptors located inside the cell rather than on its cell membrane. The word intracellular means "within or inside a cell." Molecules that cross a cell membrane to bind with a receptor are generally nonpolar and may be relatively small. These molecules are also known as ligands, these trigger how genes are turned on or off which are essential for processes like growth metabolism etc. Hormones that use intracellular receptors include thyroid, aldosterone, and steroid hormones.