What condition is an enlargement of the thyroid gland?

A condition involving enlargement of the thyroid gland is called a goiter.

The thyroid is a butterfly-shaped endocrine gland at the front of the neck. A goiter may appear as a visible or palpable swelling in that area. The enlargement describes the thyroid’s size, not necessarily whether it is producing too much, too little, or a normal amount of thyroid hormone.

Iodine deficiency is a classic cause because iodine is needed to make thyroid hormones. The thyroid may enlarge as it responds to stimulation from thyroid-stimulating hormone. Other causes include autoimmune diseases such as Hashimoto thyroiditis or Graves’ disease, thyroid nodules, inflammation, and certain medications.

A goiter can occur with hyperthyroidism, hypothyroidism, or normal thyroid function. That is why goiter is not interchangeable with hyperthyroidism, hypothyroidism, or thyroiditis: those terms describe hormone activity or inflammation, while goiter specifically describes enlargement. The British spelling is “goitre,” while “goiter” is standard in American English.