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Flashcards in thyroid and antithyroid Deck (37)
1

function of thyroid peroxidase

oxidation and organification of iodide AND coupling of mono-iodotyrosine and diodotyrosine

DIT + DIT - T4
DIT + MIT - T2

2

thyroid hormone fxn

bone growth and CNS development

enhance B1 receptors in heart = increase CO/HR/SV/contractility

Increase BMR via Na/K ATPase

Increase glycogenolysis, gluconeogenesis, lipolysis

3

thyroglobulin proteins affected by pregnancy and OCP

TBG increases

4

action of reverse T3

binds T3 receptors and blocks T3 receptors

unknown pharmalogical fxn

5

what kind of pathway do TRH, TSH, and T3/T4 use?

TRH = IP3
TSH = cAMP
T3/4 = intranuclear receptor binding

control gene expression

6

what drugs can cause primary hypothyroidism

lithium
amiodarone

7

levothyroxine

T4

8

liothyronine

T3
(not used too frequently)

9

thyroid preparations MOA

stimulation of nuclear receptors = gene expression with RNA formulation and protein synthesis

10

thyroid preparation use

hypothyroidism
cretinism
off label as weight loss supplements

11

thyroid preparation kinetics

T4 --> T3 = T3 is much more potent

any inducers can increase metabolism of thyroid hormones

12

thyroid prep AE

thyrotoxicosis:
sweating, warm skin, inc appetite, dyspnea, tachycardic, weight loss, menstrual irregularity, infertile, increased deep tendon reflexes

13

drugs used in hyperthyroidism

1) thioamides
2) iodine/salts
3) 131 Iodide
4) beta blocker
5) diatrizoate, glucocorticoids

14

propylthiouracil

thioamide

inhibits both TPO and 5-deiodinase = decreases drops in T3 AND T4

reserved for pt who are intolerant to methimazole

used in thyroid storm (b/c dec both T3 and T4)

used in 1st trimester (less teratogen than methimazole)

15

methimazole

thioamide
inhibits only TPO

16

thioamide MOA

inhibit thyroid peroxidase, iodine organification, and conversion of T4 to T3

proprylthiouracil inhibits both thyroid peroxidase and 5-deiodinase

methimazole inhibits TPO only

17

thioamide PK

slow onset - not inhibited preformed T4/T3 - takes 2 to 3 weeks

methimazole - 1x daily

PTU - 3x daily

both pass placental barrier

18

thioamide AE

agranulocytosis
hepatitis
hypothyroidism

19

lugol's solution

iodide

iodide + potassium iodidie

20

potassium iodide

iodide

saturated solution

21

Iodides MOA

inhibition of thyroid hormone synthesis = dec organification and release via brief TPO inhibition

cannot use long term use - thyroid escapes effects after 14 days = "wolff Chaikoff effect"

22

wolff chaikoff effect

"escape effect"
loss of efficacy of iodides b/c thyroid loses TPO inhibition after 14 days

if continued -- multinodular goiter

23

iodides use

pre-op for thyroidectomy = decreases size, fragility, and vascularity of tumor

PTU + b blocker + iodides = used for thyrotoxic crisis

24

Jod Basedow phenomenon

multinodular goiter that develops with continued use after wolff chaikoff effect

25

iodides AE

wolf chaikoff

chronic iodide intoxications

anaphylactoid = angioedema,

larygneal swelling

brassy taste

burning of teeth and gums

enlargement of parotid and maxillary glands

26

radioactive iodidne

taken up and sequestered by thyroid gland = damages tissue through emission of toxic beta rays

27

radioactive iodidne use

hyperthyroidism
Grave's
if refractory to other drugs

contraindicated in pregnant and nursing females

**only medication that causes permanent reduction in thyroid activity

28

radioactive iodine AE

sore throat
hypothyroidism

29

nonselective B blockers used

propranolol
nadolol
esmolol

30

B blocker MOA

competitively blocks B receptors - inhibit T4 to T3 conversion

31

B blocker use

thyroid storm/toxicosis, tremor, stage fright

32

b blocker AE

bronchospasm
AV block
HF

nadolol: longer action that propanolol, less CNS effects
esmolol: shorter acting - used for intra-operative thyroid storm

33

B blocker alternative in asthma pt

CCB: dilitazem and verapamil

34

amiodarone

structurally similar to thyroxine

iodine assoc hyperthyroidism or autoimmune med inflam - use steroids

hypothyroidism - give levothyroxine

35

iohexol/diatrizoate

suppress T4 to T3
rapidly reduces T3 concentration in thyrotoxicosis

36

lithium

inhibits release of hormones and thyroid enlarges

37

drugs that inhibit conversion of T4 to T3

1) steroids
2) propranolol
3) amiodarone
4) diatrizoate and iohexol