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- Thyroid Hormones
- NIS Symporter
- Thyroid Hormone Synthesis
- Thyroid Regulation
- Iodine Deficiency
- Iodine Excess
- Thyroid Iodine
IODINE AND THE THYROID
Iodine is an essential nutrient primarily because of its role as an indispensable component of the thyroid hormones T3 and T4. The thyroid hormones are the only iodine-containing hormones in vertebrates. Without iodine there is no biosynthesis of thyroid hormones. Therefore, thyroid function ultimately depends on an adequate supply of iodine to the gland.
A remarkably efficient and specialized system has evolved in the thyroid that ensures that most of the ingested dietary I- (the only source of I-) is accumulated in the gland and thus made available for T3 and T4 biosynthesis.
The significance of this becomes more apparent when one considers that I- is rather scarce in the environment.
In addition to this essential role in thyroid hormone formation, iodine also influences a wide variety of specific functions in the thyroid, affecting many chemical processes and even the size of the thyroid.
What are the major hormones produced by the thyroid? Why are they important? How much iodide do they contain? How do they get from the thyroid to the cells? What affects the thyroid hormone receptors? How does T4 get transformed into T3? How do extra-thyroidal processes control hormone levels in the cells? What do the hormones do in the cells?
How does iodide get into the thyroid cell? What is the NIS symporter? How does it function, and what controls it? Where is it found besides the thyroid? What are the iodine/iodide transporters besides the NIS?
How is the iodide turned into hormones? What components besides iodide are necessary for this process? What happens to the hormones once they are created?
How does the thyroid adapt to changing conditions so that it can provide the hormones that are needed? What is TSH and why is it important? How does the thyroid use iodide in its own autoregulation?
What are the effects of iodine deficiency on the thyroid? What happens to the T4, T3, and TSH when there is not very much iodine? How does the thyroid adapt to conditions of iodine deficiency? How much iodine is necessary?
What are the effects of iodine excess on the thyroid? What happens to the T4, T3, and TSH when there is lots of iodine? How does the thyroid adapt to conditions of iodine excess? How much iodine is too much?
How much iodine is in the thyroid?
How do the above principles of thyroid physiology relate to some common thyroid problems: hypothyroidism, hyperthyroidism, goiter, autoimmune issues, and cancer? What is the role of iodine in each of these?