Iodine Metabolism Flashcards
Iodine is abundant where?
sea, low on land
how much iodine needed per day?
150ug
Thyrotropin releasing hormone aka?
TRH
Thyrotropin aka?
TSH
Cretinism is?
maternal iodine deficiency causing congenitcal condition
iodine-131 does what to thyroid?
destroy
thyroid hormones operate via? act on?
- operate via membrane receptors
- direct activation of genes in DNA
Iodine used externally as?
antiseptic
Active form I2 is a?
potent oxidizer
iodinated contrast avoided with who?
patients with possible thyroid carcinoma, interferes with post-operative radioactive iodine
how much iodine do we have in our body?
20mg
top 3 sources of iodine?
kelp
marine fish
shellfish
upper limit for iodine per day?
1100ug/day
What are goitrogens? examples?
inhibit iodide uptake:
soy, cabbage, kale, broccoli
Cretinism preventable?
Yes, mothers need iodine
iodine fortification in food include?
salt
bread
Thyroid hormone alters energy levels via elevating?
ATP Acetyl-CoA NADH NADPH enzymes synthesis
how much T4 and T3 % does thyroid make?
80% T4
20% T3
precursor to T3 and T4?
tyrosine in the protein thyroglobulin
condensations of DITs and MITs to form T3 and T4 catalysed by?
thyroperoxidase
Half life of T4
T3?
T4: 6-9 days
T3: 24-36 hours
what to do with excess iodine?
reverse T3 (3,3’,5): inactive to dump
what is the uptaker for iodine?
NIS (Sodium/iodine symport)
What drives the NIS for iodine uptake?
TSH-receptor activation and cAMP 2ndary messenger
iodine-131 emits?
beta particles
Propylthiouracil/methimazole inhibit what?
thyroperoxidase
Grave’s Disease does what?
auto-antibodies activated TSH receptor = +++Thyroid hormone
T4 to T3 in liver happens how?
via Type 1 deiodinase
T4 to T3 in brain happens how?
via type 2 deiodinase
T4 to T3 in brown adipose, pituitary happens how?
within cells
thyroid hormone receptors in DNA do what? what happens when T3 gets in?
usually repress
T3 takes away inhibition
How long for T3 to produce an effect? lasts how long?
1-10 hours
lasts a few days
hyperthyroidism symptoms?
difficulty sleeping heat intolerance infertility irritability muscle weakness nervousness scant menstrual periods
hypothyroidism symptoms
arthritis cold intolerance depression dry skin fatigue forgetfulness heavy menstrual periods infertility muscle aches