The endocrine system consists of a group of glands that produce hormones -- substances produced in one part of the body that act on cells in another part of the body. The thyroid gland, located in the neck, produces two major hormones, T3 and T4, that regulate the conversion of oxygen and calories into energy, which means they affect nearly every tissue in the body. Goiter describes a condition in which the thyroid gland grows larger than normal. The Mayo Clinic reports that worldwide the most common cause of goiter is a lack of iodine in the diet.
The Institute of Medicine sets the recommended daily intake of iodine at 150 mcg per day for adults. Salt manufacturers began adding iodine to salt more than a century ago. Since then, the incidence of iodine deficiency and goiter caused by a lack of iodine has become rare in the United States. However, because only 70 percent of the world's households can get iodized salt, iodine deficiency disorders continue to plague those in other countries, according to the Salt Institute.
The symptoms caused by goiter vary depending on how large the thyroid becomes. Many experience no noticeable symptoms, and the doctor may suggest a wait-and-see approach that involves watching for additional growth and assessing the onset of any symptoms. As the goiter grows larger, it can press on the other structures in the neck such as the trachea or esophagus. This can lead to symptoms including a visible swelling at the base of the neck, coughing, difficulty swallowing, tight feeling in the throat, hoarseness or trouble breathing. Your doctor may suggest surgery to remove all or part of the thyroid gland or the use of radioactive iodine or iodine supplements.
The thyroid gland contains the only cells in the body that can absorb iodine. Because of this, doctors can use a specific form of iodine known as radioactive iodine to treat conditions of the thyroid. Usually used to treat hyperthyroidism -- the over-production of thyroid hormone -- or thyroid cancer, radioactive iodine preferentially destroys thyroid cells, resulting in a decrease in the size of the goiter.
Goiter caused by an iodine deficiency may decrease in size when you increase your intake of iodine. A quarter teaspoon of iodized salt provides 95 mcg of iodine. Seafood such as fish, shrimp and seaweed also serve as good sources of dietary iodine. Supplements in the form of potassium iodide are available. Iodine accounts for approximately 77 percent of the total weight of potassium iodide, according to the Linus Pauling Institute. Multivitamins that contain iodine can also provide up to 100 percent of the daily recommended intake.