Iodine, Selenium, Chromium Flashcards
iodine: functions
component of thyroid hormones
regulates BMR, macronutrient metabolism, growth and development
iodine: goiter development
enlargement of thyroid of any cause
endemic goiter
multinodular d/t iodine deficiency
cretinism
mental retardation, growth retardation, deaf- mutism, altered craniofacial growth and development, malocclusion
hypothyroidism
can be autoimmune, iatrogenic, congenital, chronic, hasimoto’s
hyperthyroidism
grave’s disease
iodine status
goiter rate, urine iodine excretion, TSH conc in blood, thyroglobin (dried blood spots by finger prick)
IDDs
endemic goiter, reproduction problems, neurocognitive impairment (cretin –> neurologic, myxedematous)
goitrogens
they compete w iodine for thyroidal uptake
Food: cyanogenic glucosides, glucosinolates, isoflavones
environment: perchlorate, disulfides (coal processing), smoking
Selenocysteine
synthesized by mammals, incorporated into proteins, functionally active by 21st UGA codon
selenomethionine
plants, Se replaces S in Met randomly. no specific function
Se biochem: glutathione peroxidases
removes H2O2 + lipid hydroperoxides (GPX1-4)
Se biochem: deiodinases
catalyze activation of T4–> T3
Se biochem: thioredoxin reductase
catalyzes reduction of thioredoxin for DNA synthesis
Se biochem: selenoprotein P
major transporter of Se to peripheral tissues
Se biochem: selenoprotein S
anti inflammatory in ER
Se deficiency, toxicity
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
Trivalent Cr III
in food. low absorption, low oral toxicity
Hexavalent Cr VI
toxic, strong oxidant, can penetrate cell membranes and cause tissue damage
Cr: glucose tolerance factor
nutritional yeast. protein bound, natural Cr in yeast
Cr: biochem function
(+) insulin activity, potentiates action, involved in CHO, fat, protein metabolism
Cr mechanism for glucose absorption
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
Glucose tolerance (Cr)
Cr increases glucose tolerance, potentiates action of insulin
endemic cretinism
deaf- mutism, spasticity, motor dysfunction in addition to/ instead of usual manifestations
