Thyroid & Iodine - Part 2

Medical Author: Ruchi Mathur, M.D.
Medical Editor: William C. Shiel, Jr., MD, FACP, FACR

Part 1 of this article focused on the mechanisms of iodine and iodide as related to thyroid hormone production. We outlined the amount of iodine needed for normal thyroid function and we discussed the availability and consumption of iodine throughout the world. In this section, we will discuss the effects of iodine deficiency and excess on thyroid function.

Iodine Deficiency

Most animals, including humans, have an ability to conserve the iodine within their bodies if there is a deficiency of iodine consumed in food. If an inadequate intake continues, however, the ability to make thyroid hormone is slowly depleted. Many cellular processes occur to keep the thyroid as efficient as possible and the thyroid gland often enlarges in an attempt to maintain function. Subsequently, a goiter may form as the thyroid is stimulated to try to make more thyroid hormone.

Basically, the changes in hormone levels (namely T4, T3, and TSH) are similar to those that occur in patients who develop low thyroid hormone blood levels (hypothyroidism) from an underlying disease, such as Hashimoto's disease.

Medically Reviewed by a Doctor on 12/1/2014