Iodine Metabolism and Thyroid Hormones Flashcards
What is the RDI for iodine?
150 micro grams
Why is iodine used as an antiseptic?
because it inactivates proton pumps in bacteria because it is a strong oxidiser and therefore is an antimicrobial
What are the symptoms of iodine deficiency?
underactive thyroid gland, goitre, mental and physical retardation in infants
What are the symptoms of iodine toxicity?
underactive thyroid gland, goitre
What foods are goitrogens and what do they do?
vegetables like cabbage, kale, brussel sprouts and broccoli - inhibit iodide uptake in the thyroid
Why do inland populations have more iodine deficiency than coastal populations?
because the ocean is the world’s major source of iodine
What is the world’s most common and most preventable cause of mental retardation?
cretinism (iodine deficiency)
What is the action of thyroid hormones?
determine basal metabolic rate, act as a sympathomimetic, stimulate brown fat to generate heat
What stimulates the production of thyroid hormones?
TSH from the anterior pituitary
Under what condition is thyroid hormone output greatly depressed?
starvation
What percentage of thyroid hormones released by the thyroid is T4?
80%
How much more active is T3 than T4?
four times more active
Where does the tyrosine required for thyroid hormone production come from?
the protein thyroglobulin
What is the action of thyroperoxidase?
condenses iodinated tyrosines on thyroglobulin and oxidises iodide to a chemically reactive form (iodine)
What causes iodine uptake into follicular cells?
a symport with sodium which is driven by a sodium gradient created by a sodium potassium ATPase
