Goiter refers to an abnormal enlargement of the thyroid gland, which is a butterfly-shaped gland found at the base of the neck, explains Mayo Clinic. It is often painless although a large goiter causes coughing and makes it hard for a person to breathe or swallow.
Iodine deficiency is the most common cause of goiter around the world, according to Mayo Clinic. In the United States, iodine deficiency isn't the cause of most goiters because Americans have a sufficient intake of iodine through the consumption of iodized salt. Most Americans with goiter suffer from too much or insufficient production of the thyroid hormones that develop in the gland.
The gland needs enough iodine to produce adequate thyroid hormones, says the American Thyroid Association. When the body lacks iodine and the thyroid hormone level is too low, the brain sends a signal to the thyroid, which stimulates the thyroid to produce thyroid hormones and increase in size. This abnormal growth in size becomes a goiter. Other causes of goiter include Hashimoto’s thyroiditis, Graves’ disease and multinodular goiters.
The American Thyroid Association notes that when a person has a goiter, it does not necessarily mean that his thyroid gland is malfunctioning. It indicates the presence of a condition that causes the thyroid to grow abnormally. Hyperthyroidism means the gland produces too much hormone, while hypothyroidism means the gland produces too little hormone. Euthyroidism is a condition wherein there is a correct amount of hormone.