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18 Cards in this Set
- Front
- Back
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TH regulation
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TRH -> TSH (7 transmembrane -> caMP R) -> stimulates thyroid follicles-> release T3/T4 -> neg feedback on hypothalamus
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T3 vs T4
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Iodines; 3 iodines vs 4 iodines
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thyroid hormone production
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gland transports iodine into follicle cells and makes the thyroid hormones; combine iodines with tyrosine
enzyme = thyroperoxidase to form MIT and DIT an MIT and DIT couple to form T3 or 2 DITs = T4 |
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TPO
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thyroperoxidase; responsible for oxidation and organization of iodide as well as coupling of MIt and DIT
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Thyroid binding globin
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binds most T3/T4 in blood; only free hormone is active (able to transported into each cell)
T4 deioidinated to T3 which travels to nucleus to thyroid reeptors attached to promtoer regions of genes; T3 attaches to T4-> upregulates transcriptin of that gene producing mRNA and subsequently increasd protein levels |
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only negative T3 receptor
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pituitary; T3 binds to TH receptor in nucleus; shuts off TSH production in pituitary
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What do you check for thyroid status in pt
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TSH (if pituitary is happy then the body has the approrpritate level of thyroid hormone); EXCEPT in pitutiary disease
since total levels change based on TBG total levels are least accurate (but you only care about free levels) |
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when to measure free levels of T3/4
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mainly hyperthyroidism
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high TSH
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pituitary thinks pt is not making enough thyroid hormone; tries to get signal to make more thyroid hormone (pt is tired, cold, constipated
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pt w sweaty hands w soft smooth skin
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hyperthyroidism (esp in the southwest bc no humidity so not normal to be sweaty)
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is thyroid dz familial
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yes! other ppl in the family will have thyroid rpoblems (goiters)
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primary hyperthyroidism
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problem in thyroid gland increasing T3/4; shuts off TRH and TSH (measured, low)
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Low TSH/HIGH FT4
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primary hyperthyroidism
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High TSH/High FT4
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secondary hyperthyroidism
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never do a thyroid scan after a CT scan
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thyroid wont take up iodine
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I123 thyroid scan and uptake
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radioactive iodine capsule given; absorbed into thyroid; measure radioiodine uptake; normal values 6-18% for 4 hrs, 10-35% for 24 hrs
then do a scan of the gland to see what it looks like if you pick up alot of iodine the gland is overactive (making too much TH); if you pick up little youre not making any new thyroid hormone (not necessarily hypothyroid though) |
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tx for toxic multinodular goiter
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antithyroid medication (methimazole)
propranolol (B blocker for palpitations/tremors) |
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hot vs cold nodules
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cold = nonfunctioning
hot = hyperuptake of iodine |
