48 - Thyroid and Anti-thyroid drugs

Question 1

Identify: enzyme that converts iodide to iodine:

Answer 1

thyroid peroxidase (TPO)

Question 2

Identify: protein that transports thyroid hormon in the blood:

Answer 2

thyroxine-binding globulin

Question 3

• Identify: medical emergency representing the end state of untreated hypothyroidism
• treatment:

Answer 3

• myxedema coma

- levothyroxine

Question 4

Drug class of PTU:

Answer 4

thioamide

Question 5

DOA for pregnant hyperthyroid patients:

Answer 5

PTU

Question 6

Give 2 toxicities of PTU:

Answer 6

• fulminant hepatitis

- agranulocytosis

Question 7

Drug class of methimazole

Answer 7

thioamide

Question 8

DOA for non-pregnant hyperthyroid patients:

Answer 8

methimazole

Question 9

PTU vs methimazole:

Answer 9

PTU: shorter half-life, able to inhibit peripheral conversion of T4 to T3, does not cross placenta and is not expressed in breast milk

Question 10

Effect of fetal exposure to methimazole:

Answer 10

aplasia cutis congenita

Question 11

How to treat thioamide-induced agranulocytosis:

Answer 11

discontinue PTU or methimazole, then administer G-CSF

Question 12

Iodide that can provide permanent cure for thyrotoxicosis without surgery

Answer 12

radioactive iodine (131)

Question 13

iodide used for preparation of patient for thyroidectomy:

Answer 13

potassium iodide (KISS)

Question 14

MOA of RAI:

Answer 14

emits beta rays, causing destruction of thyroid parenchyma

Question 15

MOA of KISS (2):

Answer 15

• inhibits iodine organification and hormone release

- reduce size and vascularity of the thyroid gland

Question 16

Wolff-Chaikoff effect vs Jod-Basedow phenomenon:

Answer 16

• Wolff-Chaikoff effect: ingestion of iodine causes HYPOthyroidism
• Jod-Basedow phenomenon: ingestion of iodine causes HYPERthyroidism

Question 17

This beta-blocker is able to inhibit the peripheral conversion of T4 to T3

Answer 17

propranolol

Question 18

• This drug causes clinical improvement of hyperthyroidis without altering thyroid hormone levels:
• MOA of this drug:

Answer 18

• propranolol

- physiologic antagonist

Question 19

Enumerate: (3) antithyroid drugs that act by inhibiting peripheral conversion of T4 to T3:

Answer 19

• PTU
• propranolol
• hydrocortisone

Question 20

Enumerate (3): drugs that can cause drug-induced hyperthyroidism:

Answer 20

• Clofibrate
• Amiodarone
• Methadone

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