Quiz 5: Iodine Flashcards
Iodine is an __ element
Iodine is an ultratrace element
iodine deficiency disorder (IDD) is the leading cause of __
iodine deficiency disorder (IDD) is the leading cause of mental development disorders in young children
iodine deficiency promotes
- impaired cognitive development (mild –> mental retardation (cretinism))
- stunted growth
- poor school performance
- reduced work capacity
iodine deficiency also causes
stillbirth
miscarriage
physical impairment
thyroid dysfunction
biological form of iodine
I-
what is iodine a component of
tri-iodothyonine (T3)
thyroxine (T4)
main way to meet iodine requirements
iodized salt
iodine abundance in __ is varied
iodine abundance in soil is varied
when is there increased iodine RDA
infants
pregnancy
lactation
with age
A 50% increase in maternal __ is needed to maintain maternal __ and transfer __ to fetus
A 50% increase in maternal T4 is needed to maintain maternal euthyroidism and transfer thyroid hormone to fetus
why is iodine requirement increased during pregnancy? (2)
- iodine needs to be transferred to the fetus to make fetal thyroid hormones
- increased renal iodine clearance
major food source of iodine
bread and milk
variable food sources of iodine
beans
eggs
meats
fish
fortified sources of iodine
iodized salts
goitrogens promote __ which are __
goitrogens promote goiters which are enlarged thyroid glands
goitrogen = substances that inhibits __ uptake and or __ and __ release
goitrogen = substances that inhibits iodine uptake and or organification and thyroid hormone release
3 chemical goitrogens
goitrin
perchlorate
lithium
food sources of goitrogens
- cruciferous vegetables
- cassava
- millet
- insecticides
iodine toxicity is __ and causes __ issues
iodine toxicity is rare and causes thyroid issues
2 chemical food forms of iodine
- iodide (I-) bound to amino acids
- iodate (IO3-) in bread or iodized salts
where is iodine absorbed
upper intestine (duodenum and jejunum)
iodine is secreted into
gastric lumen
in healthy adults, __% of iodine is absorbed
in healthy adults, > 90% of iodine is absorbed
main iodine transporter
NIS
NIS is dependent on __
NIS colocalizes with __ in __
NIS is inhibited by high __
NIS is dependent on Na
NIS colocalizes with ATPase in small intestine
NIS is inhibited by high I-
where is NIS found?
thyroid gland (for uptake)
lactating mammary gland (secretion into milk)
salivary glands and stomach cells (secretion into digestive tract)
NIS absorption steps
- iodate –> glutathione –> I-
- NIS pulls I- in, Na out
- NaK ATPase takes Na out, K in
- I- crosses cell to blood
70-80% of iodine is stored in __ (100-fold more than in __)
rest in _, _, and __
70-80% of iodine is stored in thyroid gland (100-fold more than in plasma)
rest in salivary glands, stomach, and ovary and testis
excretion of iodine is mainly in __(%)
rest in __
excretion of iodine is mainly in urine(80-90%)
rest in feces (10-20%)
__ have major mechanism to regulate iodine reabsorption
kidneys have major mechanism to regulate iodine reabsorption