Iodine Flashcards
Iodine is a non-metal found in what form?
Ionic form - Iodide (I-)
Where (geographically) are low amounts of Iodide typically found?
Mountainous areas (ex. Himalayans), Frequent flooding (ex. India), Remote areas away from sea (ex. Central africa)
Where is Iodide absorbed?
Throughout the GI tract
What percentage is absorbed?
Nearly 100%
What does Iodide use as a transporter?
Na+ - I- co-transporter
T4 and T3 are absorbed unchanged (no conversion needed) with a bioavailability of 75%, what does this result in for people who need T4 medication?
Allows T4 to be administered orally
What gland traps iodide the most aggressively, and by what type of transport?
Thyroid gland, with sodium-dependent active transport
What percentage of the bodies total iodine does the thyroid gland contain?
75%
What is the main function of Iodine? (hint: synthesis of 2 molecules)
synthesis of T3 (triiodothyronine) and T4 (thyroxine)
Looking at plasma concentration… is T4 or T3 more abundant in the human body?
T4 is 50x more abundant, although T3 is much more potent
What is a cofactor for all three 5’-deiodinase isoenzymes?
Selenium
What is the cofactor for thyroid peroxidase?
Iron
What vitamin deficiency will reduce the uptake of iodine?
Vitamin A
Substances that interfere with iodide metabolism are known as…
Goitrogens
What are the four goitrogens that compete with Iodide’s active transport?
Bromide (Br-), Astatide (At-) - same column periodic table
Lithium (Li-) - bipolar medication
Thiocyanate (SCN-) - cabbage, kale, broccoli
How much Iodide is secreted due to what organ having NO MECHANISM to conserve iodide?
90% secretion due to the Kidney
Iodide deficiency is seen in adults and children as two different types of disorders, what are they and generally what do they involve?
Adult: Endemic Goiter - over stim of thyroglobulin production by TSH
Children: Cretinism - motor disorders and mental deficiency
High intakes of Iodide (toxicity) can cause what to happen to the thyroid?
Thyroiditis in hyper and hypothyroidism
Supplementation is especially crucial for children at what point in their lives?
Birth to 3 years of age, otherwise mental retardation can occur
