thyroid and antithyroid

Question 1

function of thyroid peroxidase

Answer 1

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

DIT + DIT - T4
DIT + MIT - T2

Question 2

thyroid hormone fxn

Answer 2

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

Question 3

thyroglobulin proteins affected by pregnancy and OCP

Answer 3

TBG increases

Question 4

action of reverse T3

Answer 4

binds T3 receptors and blocks T3 receptors

unknown pharmalogical fxn

Question 5

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

Answer 5

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

control gene expression

Question 6

what drugs can cause primary hypothyroidism

Answer 6

lithium

amiodarone

Question 7

levothyroxine

Answer 7

T4

Question 8

liothyronine

Answer 8

T3

not used too frequently

Question 9

thyroid preparations MOA

Answer 9

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

Question 10

thyroid preparation use

Answer 10

hypothyroidism
cretinism
off label as weight loss supplements

Question 11

thyroid preparation kinetics

Answer 11

T4 –> T3 = T3 is much more potent

any inducers can increase metabolism of thyroid hormones

Question 12

thyroid prep AE

Answer 12

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

Question 13

drugs used in hyperthyroidism

Answer 13

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

Question 14

propylthiouracil

Answer 14

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)

Question 15

methimazole

Answer 15

thioamide

inhibits only TPO

Question 16

thioamide MOA

Answer 16

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

proprylthiouracil inhibits both thyroid peroxidase and 5-deiodinase

methimazole inhibits TPO only

Question 17

thioamide PK

Answer 17

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

methimazole - 1x daily

PTU - 3x daily

both pass placental barrier

Question 18

thioamide AE

Answer 18

agranulocytosis
hepatitis
hypothyroidism

Question 19

lugol’s solution

Answer 19

iodide

iodide + potassium iodidie

Question 20

potassium iodide

Answer 20

iodide

saturated solution

Question 21

Iodides MOA

Answer 21

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”

Question 22

wolff chaikoff effect

Answer 22

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

if continued – multinodular goiter

Question 23

iodides use

Answer 23

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

PTU + b blocker + iodides = used for thyrotoxic crisis

Question 24

Jod Basedow phenomenon

Answer 24

multinodular goiter that develops with continued use after wolff chaikoff effect

Question 25

iodides AE

Answer 25

wolf chaikoff chronic iodide intoxications anaphylactoid = angioedema, larygneal swelling brassy taste burning of teeth and gums enlargement of parotid and maxillary glands

Question 26

radioactive iodidne

Answer 26

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

Question 27

radioactive iodidne use

Answer 27

hyperthyroidism Grave's if refractory to other drugs contraindicated in pregnant and nursing females **only medication that causes permanent reduction in thyroid activity

Question 28

radioactive iodine AE

Answer 28

sore throat | hypothyroidism

Question 29

nonselective B blockers used

Answer 29

propranolol nadolol esmolol

Question 30

B blocker MOA

Answer 30

competitively blocks B receptors - inhibit T4 to T3 conversion

Question 31

B blocker use

Answer 31

thyroid storm/toxicosis, tremor, stage fright

Question 32

b blocker AE

Answer 32

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

Question 33

B blocker alternative in asthma pt

Answer 33

CCB: dilitazem and verapamil

Question 34

amiodarone

Answer 34

structurally similar to thyroxine iodine assoc hyperthyroidism or autoimmune med inflam - use steroids hypothyroidism - give levothyroxine

Question 35

iohexol/diatrizoate

Answer 35

suppress T4 to T3 | rapidly reduces T3 concentration in thyrotoxicosis

Question 36

lithium

Answer 36

inhibits release of hormones and thyroid enlarges

Question 37

drugs that inhibit conversion of T4 to T3

Answer 37

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