Goiter

In medicine and endocrinology, goiter is "enlargement of the thyroid gland that may increase from about 20 grams to hundreds of grams in human adults. Goiter is observed in individuals with normal thyroid function (euthyroidism), thyroid deficiency (hypothyroidism), or hormone overproduction (hyperthyroidism). Goiter may be congenital or acquired, sporadic or endemic (goiter, endemic)."

Classification
Endemic goiter is a "form of iodine deficiency disorders characterized by an enlargement of the thyroid gland in a significantly large fraction of a population group. endemic goiter is common in mountainous and iodine-deficient areas of the world where the diet contains insufficient amount of iodine."

Nodular goiter is an "enlarged thyroid gland containing multiple nodules (thyroid nodule), usually resulting from recurrent thyroid hyperplasia and involution over many years to produce the irregular enlargement. multinodular goiters may be nontoxic or may induce thyrotoxicosis.

Substernal goiter is an "enlarged thyroid gland with at least 50% of the gland situated behind the sternum. it is an unusual presentation of an intrathoracic goiter. Substernal goiters frequently cause compression on the trachea leading to deviation, narrowing, and respiratory symptoms.

Graves Disease is a "common form of hyperthyroidism with a diffuse hyperplastic goiter. It is an autoimmune disorder that produces antibodies against the thyroid stimulating hormone receptor. These autoantibodies activate the TSH receptor, thereby stimulating the thyroid gland and hypersecretion of thyroid hormones. these autoantibodies can also affect the eyes (Graves ophthalmopathy) and the skin (Graves dermopathy)."

Lingual goiter is "pathological enlargement of the lingual thyroid, ectopic thyroid tissue at the base of the tongue. It may cause upper airway obstruction; dysphagia; or hypothyroidism symptoms.