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endoII exam2 > Kinder, thyroid drugs > Flashcards

Kinder, thyroid drugs Flashcards

1
Q

What thyroid agents do we use

A

levothyroxine T4

liothyronine T3

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2
Q

what are the antithyroid agents

A

methimazole
propylthiouracil
potassium iodide

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3
Q

how is iodide transferred into thyroid gland

A

Na/iodide symporter

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4
Q

what anions impair iodide transport

A

thiocyanate, pertechnetate, perchlorate

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5
Q

how does iodide travel to the follicular lumen

A

iodide transporter called pendrin

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6
Q

what oxidizes iodide

A

thyroidal peroxidase

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7
Q

what do thioamide drugs block

A

thyroid peroxidase

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8
Q

what drugs can inhibit 5’ deiodinase needed to convert T4 to T3

A

amiodarone, iodinated contrast media, beta blockers, corticosteroids, severe illness, starvation

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9
Q

what inhibits TSH release

A

somatostatin, dopamine T3T4

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10
Q

thyroid effects are from what process

A

activation of nuclear R leading to protein synthesis

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11
Q

which type of thyroid syndrome causes decreased drug metabolism? increased warfarin requirement?

A

hypothyroidism

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12
Q

where is T4 absorbed

A

duodenum and ileum

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13
Q

what can alter absorption of given thyroid hormones

A

severe myxedema with ileus

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14
Q

how does T3 T4 clearance change in hypo and hyper thyroidism

A

in hyper clearance is increased

in hypo clearance is decreased

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15
Q

what agents increase hepatic CYP and enhance degradation of thyroid hormone

A

rifampin, phenobarbital, carbamazepine, phenytoin, HIV protease inhibitors

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16
Q

what agents interfere with T4 absorption

A

oral bisphosphonates, bile acid sequestrants, cipro, ppis, sucralfate, antacids, bran, soy, coffee

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17
Q

what agents induce autoimmune thyroid disease with hypo or hyperthyroidism

A

INF-a
lithium
amiodarone

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18
Q

CI T2 liothyronine

A

those with cardiac disease because increased risk for cardiotoxicity

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19
Q

why is T3 replacement not commonly used

A

requires multiple daily dosing, higher cost, difficulty monitoring

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20
Q

what are the thioamides

A

meth`imazole, propylthiouracil

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21
Q

MOA thioamides

A

prevent thyroid hormone synthesis

inhibit thyroid perozidase catalyzed reactions, blocks iodine organification, blocks coupling of iodotyrosines

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22
Q

what additional affect does PTU have

A

peripheral deiodination T4 to T3

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23
Q

onset of action of thioamides and why

A

slow 3-4 weeks before stores of T4 depleted because affects synthesis not release

24
Q

What thioamide is more portent

A

methimazole

25
Q

what thioamide is rec for pregnant women in 1st trimester or someone in thyroid storm

A

PTU

26
Q

why is PTU preferred in pregnancy

A

protein bound so crosses placenta less readily

27
Q

adverse effects to thioamides

A

maculopapular rash with fever sometimes
urticarial rash, vasculitis, lupus-like reaction, lymphadenopathy, hypoprothrombinemia, exfoliative dermatitis, acute arthralgia

28
Q

What is an adverse effect PTU

A

severe hepatitis

29
Q

most dangerous complication with thioamides

A

agranulocytosis

30
Q

What are the anion inhibitors we use in hyperthyroidism

A

perchlorate, pertechnetate and thiocynate which competitively inhibit iodide transport mech blocking iodide uptake

31
Q

what is MOA potassium iodide

A

inhibit iodide rganification and hormone release, decrease size and vascularity of hyperplastic gland

32
Q

major action potassium iodidie

A

inhibits hormone release (possibly inhibition thyroglobulin proteolysis)

33
Q

therapeutic use of potassium iodide

A

thyroid storm
preoperative reduction hyperplastic gland
block thyroidal uptake of radioactive isotopes of iodine in a radiation EM
after thioamide therapy

34
Q

why do you use potassium iodide after thioamide use

A

may delay thioamide by increasing intraglandular stores of iodine

35
Q

whye should iodides never be used alone

A

gland escapes block in 2-8 weeks and withdrawl may produce severe exacerbation of thyrotoxicosis in iodine enriched gland

36
Q

Adverse effects iodidies

A

uncommon
acneiform rash, swollen salivary glands, mucous membrane ulcerations, conjunctivitis, rhinorrhea, drug fever, metallic taste, bleeding disorders, anaphylactic reactions

37
Q

are iodides used in pregnancy

A

no because cross placenta and can cause fetal goiter

38
Q

MOA radioactive iodine

A

destruction of thyroid parenchyma thorugh epithelial swelling, necrosis, follicular disruption, edema and leukocyte infiltration

39
Q

advantages radioactive iodine

A

easy administration, effective, low expense, absence pain

40
Q

CI RI iodine

A

pregnancy or breast feeding

destroys fetal thyroid gland

41
Q

which medications can improve the Sx of hyperthyroism but do not alter the thyroid hormone

A

beta blockers: metoprolol, propanolol, atenolol

42
Q

general Tx strategy for hashimoto

A

levothyroxine unless drug induced hypothyroidism

43
Q

how long does it take for levothyroxine to work

A

6-8 weeks

44
Q

signs of thyroxine toxicity

A

children: restless ness, insomnia, acclerated bone maturation and growth
adults: increased nervousness, heat intolerance, episodes of palpitations and tachy, unexplained weight loss

45
Q

chronic overTx with T4 can lead to what

A

a fib and accelerated osteoporosis

46
Q

hypothyroid patient has progressive weakness, stupor, hypothermia, hypoventilation, hypoglycemia, hypoNa and water intoxication, shocky

A

myxedema coma! medical EM!!

47
Q

Tx myxedema coma

A

IV levothyroxine loading dose with following mainta=enance doses

48
Q

What is your worry in myxedma with patient who has CAD

A

low levels thyroxine protect heart from increasing demands so want to avoid provoking cardiac event with drugs

49
Q

what is preferred patient for antithyroid drugs

A

young patients with small glands and mild disease

50
Q

preferred patient for thyroidectomy

A

large glands or multinodular goiters hyperthyroidism

51
Q

what should you do prior to thyroidectomy

A

Tx with potassium iodide 10-14 days prior to diminish gland vascularity

52
Q

preferred patient for radioactive iodine

A

over 21 y.o

no heart disease

53
Q

how do you Tx patient with heart disease with Radioactive iodine

A

antithyroid drugs until euthyroid
stop medication 3-5 days before RAI, may resume 3-7 days post
taper antithyroid medication over 4-6 weeks as thyroid functio normalizes

54
Q

what are adjunts to antithyroid therapy

A

beta blockers to control tachy, HTN and a fib

55
Q

if patient cannot have beta blocker how do you treat heart when alost on antithyroid meds

A

diltiazem

CaCh blocker

56
Q

management thyroid storm

A

beta blocker
potassium iodidie to prevent release of thyroid hormones
PTU to block synthesis
hydrocortisone IV to protect against shock
supportive therapy for fever, or underlying diseases

57
Q

what is used last resort to lower circulating thyroxine in thyroid storm

A

oral bile acid sequestrants, plasmapheresis or peritoneal dialysis

endoII exam2 (18 decks)

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