Thyroid Pharm

Question 1

Explain the synthesis of thyroid hormone?

Answer 1

In the thyroid gland, there are many follicles. Each follicle has a lumen surrounded by a layer of epithelium. Inside the lumen, thyroglobulin is waiting to be iodinated by iodine. As the thyroid gland takes up iodide, it is oxidized to iodine by peroxidase. Then the iodine iodinates the tyrosine residues of thyroglobulin, making DIT and MIT. Two moles of DIT with thyroglobulin gives us T4 and one MIT and one DIT with thyroglobulin gives us T3.

Question 2

What three agents can block iodine from iodinating thyroglobulin?

Answer 2

Iodide, thioamides, and PTU

Question 3

What two agents can block the production of T4 and T3 after getting DIT and MIT?

Answer 3

Thioamide and PTU

Question 4

What agent can block proteolysis of T3 and T4?

Answer 4

Iodide

Question 5

What 5 major agents can block peripheral conversion of T4 to T3?

Answer 5

Radiocontrast media, beta blockers, corticosteroids, amiodarone, and PTU

Question 6

What are the two fates of T4 once in peripheral circulation?

Answer 6

Deiodinated to T3 or inactivated

Question 7

What is the relationship between CYP 450s and thyroid hormone?

Answer 7

Drugs that induce CYP 450 activity increase metabolism of thyroid hormone

Question 8

Of T3 and T4, which one is used as the thyroid replacement therapy of choice and why?

Answer 8

T4. Lower cost, more stable and longer half life.

Question 9

What do we use for short term suppression of TSH?

Answer 9

T3

Question 10

3 ways we reduce thyroid activity and the effect of thyroid hormone?

Answer 10

Block production, block interaction with target tissue, destroy thyroid gland with radiation or surgery.

Question 11

If anti thyroid medicine is required for a pregnant lady, how do we use the two?

Answer 11

PTU for first semester, methimazole for second and third trimesters

Question 12

4 functions of thioamides?

Answer 12

Blocks oxidation of iodide, blocks iodination of tyrosine residues, blocks coupling of MIT and DIT to form t3 and t4, and blocks peripheral conversion of t4 to t3.

Question 13

What is the most common adverse effect of thioamides?

Answer 13

Rash with system effects like fever, nausea and GI problems.

Question 14

What is a unique adverse effect more common to PTU and one more common to meth?

Answer 14

Hepatitis

Jaundice

Question 15

What is the most serious complication of using a thioamide, even thought it is more rare?

Answer 15

Huge drop in white blood cell count.

Question 16

What is the MOA of anion inhibitors?

Answer 16

They block the uptake of iodide into the thyroid gland

Question 17

What is the MOA of iodides?

Answer 17

Block organification and hormone release from the thyroid gland.

Question 18

3 clinical uses of iodide?

Answer 18

Thyroid storm, preoperative reduction of a hyperplastic thyroid gland, block the thyroid from taking up radioactive iodine in a radiation emergency

Question 19

What is a contraindication of iodide?

Answer 19

Pregnancy because it can cross the placenta

Question 20

What is the clinical use for radioactive iodine?

Answer 20

Thyrotoxicosis

Question 21

What is the clinical use of beta blockers and what are the two ways they work? Also, which beta blocker is most commonly used?

Answer 21

Thyrotoxicosis or thyroid storm.
They help with the fact that many symptoms of too much thyroid hormone are sympathetic.
Block peripheral conversion of t4 to t3

Question 22

What are the three special populations to consider with thyroid replacement?

Answer 22

Myxedema coma, myxedema and CAD, and hypo and pregnancy.

Question 23

What is myxedema coma and how do we treat it with thyroid?

Answer 23

End state of untreated hypo.

IV.

Question 24

What to consider about myxedema and CAD?

Answer 24

Treat the myxedema cautiously to not provide a cardiac event.

Question 25

What to consider with hypo and pregnancy?

Answer 25

Women who normally hypo are infertile and need replacement. Also, fetal brain development depends on maternal t4.

Question 26

When would we use PTU or meth for Graves’ disease and which one is more preferred and why?

Answer 26

Young paints with small glands, mild disease.

Meth because its once a day.

Question 27

When would we consider surgically removing the thyroid for graves?

Answer 27

Patients with very large glands and multi nodular goiters.

Question 28

When is radioactive iodine the preferred treatment For graves? What are the 3 patient populations that are the exception and what do you do with them?

Answer 28

Really anyone over 21 this is good stuff.

Heart problems, severe thyroid elevation and elderly just go with anti thyroid drugs until stable.

Question 29

What can we use to manage tachycardia in a hyper patient when beta blockers are contraindicated? Give an example of a drug.

Answer 29

Calcium channel blockers like diltiazem

Question 30

What 4 drugs to give for thyroid storm and why?

Answer 30

Beta blockers to control arrhythmia
Potassium iodide to prevent release of hormone
PTU or meth to clock hormone synthesis
IV hydrocortisone to protect against shock and peripheral conversion of t4 to t3

Question 31

In rare situations, what can we do if the thyroid storm regimen isnt working for storm?

Answer 31

Plasmapheresis or peritoneal dialysis to take off thyroid hormone