What is the difference between iodide and iodine? which is beneficial for goiter?

What is the difference between iodide and iodine? which is beneficial for goiter?

thyroid follicles take up iodide to form t3 and t4 but iodine blocks the formation of t3 and t4?

User Comments

1. Iodine is an element, I
   
   Iodide is an ion that forms compounds such as Postassium Iodide, KI.
   
   I believe elemental iodine is poisonous and should not be taken orally, but KI is added to salt to make it iodized.
2. Iodine does not block the formation of T3 and T4, but the key element. During the process of transformation, iodine binds with other polymers and become ionized, a state called iodide. Only when ionized, can iodine be active and interact with other elements.
   
   The cause of goiter is iodine deficiency, and the body tries to compensate the deficiency with enlarged thryroid gland. T3 and T4 both are beneficial to goiter. The difference is T4 is usually converted to T3 by deiodinases, so T3 is considered as the major thryroid hormone, altough the plasma concentration of T4 is much higher.