Iodine is an essential dietary component that is needed to maintain normal thyroid function. Typical sources of iodine include, breads, chesse, cow’s milk, eggs, frozen yogurt, ice cream, iodized table salt, saltwater fish, seaweed, shellfish, soy milk and soy sauce.(1) Iodine deficiency has been almost completely eradicated in the United States since the introduction of iodized salt in the 1920′s-30′s. In the US, the Recommended Daily Allowance (RDA) for Iodine is 150ug per day.
Approximately 40% of the world remains at risk for iodine deficiency.(1)
The thyroid gland is made up of follicular cells. Thyroxine (T4) and Triiodothyronie (T3) are thyroid homones that are made inside the follicular of the thyroid gland. Dietary iodine is absorbed through the gastrointestinal tract and is then concentrated within the thyroid. It is then used by the follicular cell as an essential component of the thyroid hormones.
T3 and T4 are secreted from the thyroid gland under the regulation of Thyroid Stimulating Hormone (TSH) that is made in the anterior pituitary gland. TSH is released in response to low plasma levels of T3 and T4.
The majority of thyroid hormone is released from the thyroid gland as T4; however, once release from the thyroid, T4 is converted to T3. T3 is the metabolically active form of the hormone. T3 is responsible for increasing the body’s Basal Metabolic Rate (BMR). The BMR is the amount of energy that is expended by a person at rest. An increase in BMR leads to an increase in oxygen and energy consumption. T3 acts on the majority of tissues within the body.
A dietary iodine deficiency results in a deficiency in thyroid hormones (T3 and T4). The result can be hypothyroidism in adults, cretinism in children and in some cases nodular goiter.
A goiter is any swelling of the thyroid gland. Endemic goiter is a type of goiter that is associated with dietary iodine deficiency. Typically endemic goiter can be treated medically, however, in advanced cases where the mass encroaches upon or compresses nearby structures such as the trachea, surgical intervention is necessary.
The Struma Classification of Goiters:
Class I – only found by palpation.
Class II – can be easily seen.
Class III – large, pressure results in compression marks.
- The American Thyroid Association (thyroid.org)