Iodine, Selenium, Chromium

Question 1

iodine: functions

Answer 1

component of thyroid hormones

regulates BMR, macronutrient metabolism, growth and development

Question 2

iodine: goiter development

Answer 2

enlargement of thyroid of any cause

Question 3

endemic goiter

Answer 3

multinodular d/t iodine deficiency

Question 4

cretinism

Answer 4

mental retardation, growth retardation, deaf- mutism, altered craniofacial growth and development, malocclusion

Question 5

hypothyroidism

Answer 5

can be autoimmune, iatrogenic, congenital, chronic, hasimoto’s

Question 6

hyperthyroidism

Answer 6

grave’s disease

Question 7

iodine status

Answer 7

goiter rate, urine iodine excretion, TSH conc in blood, thyroglobin (dried blood spots by finger prick)

Question 8

IDDs

Answer 8

endemic goiter, reproduction problems, neurocognitive impairment (cretin –> neurologic, myxedematous)

Question 9

goitrogens

Answer 9

they compete w iodine for thyroidal uptake

Food: cyanogenic glucosides, glucosinolates, isoflavones

environment: perchlorate, disulfides (coal processing), smoking

Question 10

Selenocysteine

Answer 10

synthesized by mammals, incorporated into proteins, functionally active by 21st UGA codon

Question 11

selenomethionine

Answer 11

plants, Se replaces S in Met randomly. no specific function

Question 12

Se biochem: glutathione peroxidases

Answer 12

removes H2O2 + lipid hydroperoxides (GPX1-4)

Question 13

Se biochem: deiodinases

Answer 13

catalyze activation of T4–> T3

Question 14

Se biochem: thioredoxin reductase

Answer 14

catalyzes reduction of thioredoxin for DNA synthesis

Question 15

Se biochem: selenoprotein P

Answer 15

major transporter of Se to peripheral tissues

Question 16

Se biochem: selenoprotein S

Answer 16

anti inflammatory in ER

Question 17

Se deficiency, toxicity

Answer 17

keshan: cardiomyopathy
kashin beck: osteoarthritis, necrotic degradation of chondrocytes

Toxicity: selenosis. loss of hair/ nails, skin lesions, garlic breath, tooth decay, abnormalities of nervous system

Question 18

Trivalent Cr III

Answer 18

in food. low absorption, low oral toxicity

Question 19

Hexavalent Cr VI

Answer 19

toxic, strong oxidant, can penetrate cell membranes and cause tissue damage

Question 20

Cr: glucose tolerance factor

Answer 20

nutritional yeast. protein bound, natural Cr in yeast

Question 21

Cr: biochem function

Answer 21

(+) insulin activity, potentiates action, involved in CHO, fat, protein metabolism

Question 22

Cr mechanism for glucose absorption

Answer 22

LMWCr/chromodulin. oligopeptide that transports Cr in body from Asp, Cys, Glu, Gly, +4 Cr centers.
interacts w insulin receptor, prolonging kinase activity by (+) tyr kinase pathway –> inc glucose absorption

Question 23

Glucose tolerance (Cr)

Answer 23

Cr increases glucose tolerance, potentiates action of insulin

Question 24

endemic cretinism

Answer 24

deaf- mutism, spasticity, motor dysfunction in addition to/ instead of usual manifestations

Question 25

myxedematous cretinism

Answer 25

severe iodine deficiency, hypothyroidism in mom 3rd trimester, delayed growth of long bones, myxedema, sometimes goiter