Kinder, thyroid drugs

Question 1

What thyroid agents do we use

Answer 1

levothyroxine T4

liothyronine T3

Question 2

what are the antithyroid agents

Answer 2

methimazole
propylthiouracil
potassium iodide

Question 3

how is iodide transferred into thyroid gland

Answer 3

Na/iodide symporter

Question 4

what anions impair iodide transport

Answer 4

thiocyanate, pertechnetate, perchlorate

Question 5

how does iodide travel to the follicular lumen

Answer 5

iodide transporter called pendrin

Question 6

what oxidizes iodide

Answer 6

thyroidal peroxidase

Question 7

what do thioamide drugs block

Answer 7

thyroid peroxidase

Question 8

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

Answer 8

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

Question 9

what inhibits TSH release

Answer 9

somatostatin, dopamine T3T4

Question 10

thyroid effects are from what process

Answer 10

activation of nuclear R leading to protein synthesis

Question 11

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

Answer 11

hypothyroidism

Question 12

where is T4 absorbed

Answer 12

duodenum and ileum

Question 13

what can alter absorption of given thyroid hormones

Answer 13

severe myxedema with ileus

Question 14

how does T3 T4 clearance change in hypo and hyper thyroidism

Answer 14

in hyper clearance is increased

in hypo clearance is decreased

Question 15

what agents increase hepatic CYP and enhance degradation of thyroid hormone

Answer 15

rifampin, phenobarbital, carbamazepine, phenytoin, HIV protease inhibitors

Question 16

what agents interfere with T4 absorption

Answer 16

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

Question 17

what agents induce autoimmune thyroid disease with hypo or hyperthyroidism

Answer 17

INF-a
lithium
amiodarone

Question 18

CI T2 liothyronine

Answer 18

those with cardiac disease because increased risk for cardiotoxicity

Question 19

why is T3 replacement not commonly used

Answer 19

requires multiple daily dosing, higher cost, difficulty monitoring

Question 20

what are the thioamides

Answer 20

meth`imazole, propylthiouracil

Question 21

MOA thioamides

Answer 21

prevent thyroid hormone synthesis

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

Question 22

what additional affect does PTU have

Answer 22

peripheral deiodination T4 to T3

Question 23

onset of action of thioamides and why

Answer 23

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

Question 24

What thioamide is more portent

Answer 24

methimazole

Question 25

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

Answer 25

PTU

Question 26

why is PTU preferred in pregnancy

Answer 26

protein bound so crosses placenta less readily

Question 27

adverse effects to thioamides

Answer 27

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

Question 28

What is an adverse effect PTU

Answer 28

severe hepatitis

Question 29

most dangerous complication with thioamides

Answer 29

agranulocytosis

Question 30

What are the anion inhibitors we use in hyperthyroidism

Answer 30

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

Question 31

what is MOA potassium iodide

Answer 31

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

Question 32

major action potassium iodidie

Answer 32

inhibits hormone release (possibly inhibition thyroglobulin proteolysis)

Question 33

therapeutic use of potassium iodide

Answer 33

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

Question 34

why do you use potassium iodide after thioamide use

Answer 34

may delay thioamide by increasing intraglandular stores of iodine

Question 35

whye should iodides never be used alone

Answer 35

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

Question 36

Adverse effects iodidies

Answer 36

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

Question 37

are iodides used in pregnancy

Answer 37

no because cross placenta and can cause fetal goiter

Question 38

MOA radioactive iodine

Answer 38

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

Question 39

advantages radioactive iodine

Answer 39

easy administration, effective, low expense, absence pain

Question 40

CI RI iodine

Answer 40

pregnancy or breast feeding | destroys fetal thyroid gland

Question 41

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

Answer 41

beta blockers: metoprolol, propanolol, atenolol

Question 42

general Tx strategy for hashimoto

Answer 42

levothyroxine unless drug induced hypothyroidism

Question 43

how long does it take for levothyroxine to work

Answer 43

6-8 weeks

Question 44

signs of thyroxine toxicity

Answer 44

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

Question 45

chronic overTx with T4 can lead to what

Answer 45

a fib and accelerated osteoporosis

Question 46

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

Answer 46

myxedema coma! medical EM!!

Question 47

Tx myxedema coma

Answer 47

IV levothyroxine loading dose with following mainta=enance doses

Question 48

What is your worry in myxedma with patient who has CAD

Answer 48

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

Question 49

what is preferred patient for antithyroid drugs

Answer 49

young patients with small glands and mild disease

Question 50

preferred patient for thyroidectomy

Answer 50

large glands or multinodular goiters hyperthyroidism

Question 51

what should you do prior to thyroidectomy

Answer 51

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

Question 52

preferred patient for radioactive iodine

Answer 52

over 21 y.o | no heart disease

Question 53

how do you Tx patient with heart disease with Radioactive iodine

Answer 53

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

Question 54

what are adjunts to antithyroid therapy

Answer 54

beta blockers to control tachy, HTN and a fib

Question 55

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

Answer 55

diltiazem | CaCh blocker

Question 56

management thyroid storm

Answer 56

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

Question 57

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

Answer 57

oral bile acid sequestrants, plasmapheresis or peritoneal dialysis