thyroid and antithyroid Flashcards

1
Q

function of thyroid peroxidase

A

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

DIT + DIT - T4
DIT + MIT - T2

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2
Q

thyroid hormone fxn

A

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

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3
Q

thyroglobulin proteins affected by pregnancy and OCP

A

TBG increases

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4
Q

action of reverse T3

A

binds T3 receptors and blocks T3 receptors

unknown pharmalogical fxn

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5
Q

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

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

control gene expression

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6
Q

what drugs can cause primary hypothyroidism

A

lithium

amiodarone

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7
Q

levothyroxine

A

T4

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8
Q

liothyronine

A

T3

not used too frequently

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9
Q

thyroid preparations MOA

A

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

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10
Q

thyroid preparation use

A

hypothyroidism
cretinism
off label as weight loss supplements

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11
Q

thyroid preparation kinetics

A

T4 –> T3 = T3 is much more potent

any inducers can increase metabolism of thyroid hormones

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12
Q

thyroid prep AE

A

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

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13
Q

drugs used in hyperthyroidism

A

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

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14
Q

propylthiouracil

A

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)

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15
Q

methimazole

A

thioamide

inhibits only TPO

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16
Q

thioamide MOA

A

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

proprylthiouracil inhibits both thyroid peroxidase and 5-deiodinase

methimazole inhibits TPO only

17
Q

thioamide PK

A

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

methimazole - 1x daily

PTU - 3x daily

both pass placental barrier

18
Q

thioamide AE

A

agranulocytosis
hepatitis
hypothyroidism

19
Q

lugol’s solution

A

iodide

iodide + potassium iodidie

20
Q

potassium iodide

A

iodide

saturated solution

21
Q

Iodides MOA

A

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
Q

wolff chaikoff effect

A

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

if continued – multinodular goiter

23
Q

iodides use

A

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

PTU + b blocker + iodides = used for thyrotoxic crisis

24
Q

Jod Basedow phenomenon

A

multinodular goiter that develops with continued use after wolff chaikoff effect

25
Q

iodides AE

A

wolf chaikoff

chronic iodide intoxications

anaphylactoid = angioedema,

larygneal swelling

brassy taste

burning of teeth and gums

enlargement of parotid and maxillary glands

26
Q

radioactive iodidne

A

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

27
Q

radioactive iodidne use

A

hyperthyroidism
Grave’s
if refractory to other drugs

contraindicated in pregnant and nursing females

**only medication that causes permanent reduction in thyroid activity

28
Q

radioactive iodine AE

A

sore throat

hypothyroidism

29
Q

nonselective B blockers used

A

propranolol
nadolol
esmolol

30
Q

B blocker MOA

A

competitively blocks B receptors - inhibit T4 to T3 conversion

31
Q

B blocker use

A

thyroid storm/toxicosis, tremor, stage fright

32
Q

b blocker AE

A

bronchospasm
AV block
HF

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

33
Q

B blocker alternative in asthma pt

A

CCB: dilitazem and verapamil

34
Q

amiodarone

A

structurally similar to thyroxine

iodine assoc hyperthyroidism or autoimmune med inflam - use steroids

hypothyroidism - give levothyroxine

35
Q

iohexol/diatrizoate

A

suppress T4 to T3

rapidly reduces T3 concentration in thyrotoxicosis

36
Q

lithium

A

inhibits release of hormones and thyroid enlarges

37
Q

drugs that inhibit conversion of T4 to T3

A

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