Iodine

Question 1

Iodine is a non-metal found in what form?

Answer 1

Ionic form - Iodide (I-)

Question 2

Where (geographically) are low amounts of Iodide typically found?

Answer 2

Mountainous areas (ex. Himalayans), Frequent flooding (ex. India), Remote areas away from sea (ex. Central africa)

Question 3

Where is Iodide absorbed?

Answer 3

Throughout the GI tract

Question 4

What percentage is absorbed?

Answer 4

Nearly 100%

Question 5

What does Iodide use as a transporter?

Answer 5

Na+ - I- co-transporter

Question 6

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?

Answer 6

Allows T4 to be administered orally

Question 7

What gland traps iodide the most aggressively, and by what type of transport?

Answer 7

Thyroid gland, with sodium-dependent active transport

Question 8

What percentage of the bodies total iodine does the thyroid gland contain?

Answer 8

75%

Question 9

What is the main function of Iodine? (hint: synthesis of 2 molecules)

Answer 9

synthesis of T3 (triiodothyronine) and T4 (thyroxine)

Question 10

Looking at plasma concentration… is T4 or T3 more abundant in the human body?

Answer 10

T4 is 50x more abundant, although T3 is much more potent

Question 11

What is a cofactor for all three 5’-deiodinase isoenzymes?

Answer 11

Selenium

Question 12

What is the cofactor for thyroid peroxidase?

Answer 12

Iron

Question 13

What vitamin deficiency will reduce the uptake of iodine?

Answer 13

Vitamin A

Question 14

Substances that interfere with iodide metabolism are known as…

Answer 14

Goitrogens

Question 15

What are the four goitrogens that compete with Iodide’s active transport?

Answer 15

Bromide (Br-), Astatide (At-) - same column periodic table
Lithium (Li-) - bipolar medication
Thiocyanate (SCN-) - cabbage, kale, broccoli

Question 16

How much Iodide is secreted due to what organ having NO MECHANISM to conserve iodide?

Answer 16

90% secretion due to the Kidney

Question 17

Iodide deficiency is seen in adults and children as two different types of disorders, what are they and generally what do they involve?

Answer 17

Adult: Endemic Goiter - over stim of thyroglobulin production by TSH
Children: Cretinism - motor disorders and mental deficiency

Question 18

High intakes of Iodide (toxicity) can cause what to happen to the thyroid?

Answer 18

Thyroiditis in hyper and hypothyroidism

Question 19

Supplementation is especially crucial for children at what point in their lives?

Answer 19

Birth to 3 years of age, otherwise mental retardation can occur