Iodine is necessary for the synthesis of the thyroid hormonestriiodothyronine and thyroxine (T3 and T4). In conditions producing endemic goitre, when iodine is not available, these hormones cannot be made. In response to low thyroid hormones, the pituitary gland releases thyroid stimulating hormone (TSH). Thyroid stimulating hormone acts to increase synthesis of T3 and T4, but it also causes the thyroid gland to grow in size by increasing cell division.
Goitre is more common among women, but this includes the many types of goitre caused by autoimmune problems, and not only those caused by simple lack of iodine.
Treatment for goitre may not be necessary if the goitre is small. Hypothyroidism should be treated, and this treatment often leads to a substantial reduction in the size of the goitre. Removal of the goitre may be necessary if it causes difficulty with breathing or swallowing. There is now an alternative to surgery in large goitres. Radioiodine therapy with or without the pre-injection of a synthetic thyroid stimulating hormone, TSH, can relieve obstruction and reduce the size of the goitre by 30-65%. But removal of a goitre requires removing the thyroid. The complete removal of the thyroid gland removes the body's ability to produce thyroid hormone. In this case, oral thyroxine supplements are necessary to avoid harm from hypothyroidism.
History and future
Paracelsus (born Philippus Aureolus Theophrastus Bombastus von Hohenheim) (1493–1541) was the first to describe the connection between goitre and the consumption of minerals, specifically lead in drinking water.
Goitre was previously common in many areas that were deficient in iodine in the soil. For example, in the English Midlands, the condition was known as Derbyshire Neck. In the United States, goitre was found in the Great Lakes, Midwest, and Intermountain regions. The condition now is practically absent in affluent nations, where table salt is supplemented with iodine. However, it is still prevalent in India, Central Asia and Central Africa.
Some health workers fear that a resurgence of goitre might occur because of the trend to use rock salt and/or sea salt, which has not been fortified with iodine.
New research indicates that there may in fact be a tendency to inherit an increased vulnerability to goitre.