Sketchy Pharm: Propylthiouracil, Methimazole, and Levothyroxine

Question 1

Iodide enters the follicular cells through ______________ channels.

Answer 1

sodium/iodide symporter (like the guy carrying a box of peaNAts and carrying a test tube of iodide into the follicuLAIR)

Question 2

Iodide gets _____________ before being stored in the follicle.

Answer 2

oxidized to iodine (like the oxidized rust on the truck storing iodine)

Question 3

What enzyme oxidizes iodide in the follicles?

Answer 3

Thyroid peroxidase (like the briefcase with TransPOrt written on it)

Question 4

_______________ is located in the folicle and can accept many iodine residues.

Answer 4

Thyroglobulin (like the Thyro-Global food truck)

Question 5

T4 and T3 get cleaved from thyroglobulin in which cell compartment?

Answer 5

Inside the follicular cells (represented by the T4 and T3 bombs in the lair – the follicuLAIR)

Question 6

________________ converts T4 to T3.

Answer 6

5’ deiodinase

Question 7

What does T3 do to peripheral tissues?

Answer 7

It upregulates the expression of adrenergic receptors, thereby making the tissues more sensitive to catecholamines.

(Think of the swarm of CATfish in the background and the guy trembling in front of them with the large bowtie that represents hyperthyroidism.)

Question 8

In the U.S., most people with Graves disease are treated with _______________.

Answer 8

radioactive iodide (like the guy who brought the glowing tube of iodide into the lair that burned a hole in the floor)

Question 9

What are two symptoms of radioactive iodide treatment?

Answer 9

• Hypothyroidism due to destruction of the thyroid (like the guy with the untied bowtie)
• Exacerbation of hyperthyroidism (like the guy trembling with fear in the lair after bringing in toxic iodide)
• Worsening of ophthalmopathy (like the night vision goggles worn by the guy infiltrating the lair)

Question 10

_______________ is the drug of choice for hyperthyroidism because it is 10x more potent.

Answer 10

Methimazole

Question 11

What two drugs can treat hyperthyroidism?

Answer 11

• Propylthiouracil (PTU) (like the guy shooting the gun – PTU! PTU! –at the TransPOrter)
• Methimazole (like the evil math equation board being kicked by the antithyroid agent)

Question 12

In addition to inhibiting thyroid peroxidase, PTU also _______________.

Answer 12

inhibits 5’ deiodinase (like the PTU! PTU! shooting of the agent in the bar)

Question 13

How do beta-blockers treat hyperthyroidism?

Answer 13

Two ways:

• They decrease the effect of increased adrenergic receptors (like the agent shooting beta guns at the CATfish tank).
• They block 5’ deiodinase (like the agent shooting his other bugle gun at the henchman who’s converting T4 to T3 bombs).

Question 14

Beta-blockers, PTU, and _____________ all decrease peripheral conversion of T4.

Answer 14

glucocorticoids (like the moon discs being thrown at the converter henchman)

Side note: glucocorticoids can also lessen exophthalmos.

Question 15

What are the side effects of PTU and methimazole?

Answer 15

• Hepatotoxicity (broken liver beaker next to the PTU! PTU! agent
• Maculopapular rash (orange spots on agent’s suit)
• Agranulocytosis (think of the sand timer in the background with the self-destruct sequence initiated)
• Aplastic anemia (like the plastic bones beneath the console)
• Lupus (guard wolf)

Question 16

PTU is not often used because of increased likelihood of side effects, but it is still used in ____________.

Answer 16

pregnant women (like the MaTH board hitting the pregnant woman right in the bump with the tarantula –this symbolizes that methimazole is a teratogen)

Question 17

Severe hypothyroidism can result in ______________.

Answer 17

myxedema coma

Question 18

Any _____________ can decrease the uptake of iodide.

Answer 18

anion –perchlorate, pertechnetate – (like the agent sneaking into the lair in the anion crate)