Thyroid Disorders

Question 1

• Gold standard
• Most sensitive index for hyperthyroidism and replacement therapy

Answer 1

TSH

Question 2

What does the TSH test measure?

Answer 2

pituitary TSH level

Question 3

• Most accurate
• May be normal in mild thyroid disease

Answer 3

FreeT4

Question 4

What does FreeT4 test measure?

Answer 4

direct measurement of free thyroxine

Question 5

ATgA

Answer 5

• Antibodies to thyroglobulin
• increased in autoimmune disease
• undetectable during remission

Question 6

TPO-Ab

Answer 6

• thyroperoxidase antibodies
• more sensitive of the two antibodies

Question 7

TRAb

Answer 7

• thyroid receptor stimulating antibody
• confirms Graves’ disease

Question 8

What are the hyperthyroidism treatment options?

Answer 8

• thioamides
• radioactive iodine (RAI)
• surgery (thyroidectomy)

Question 9

What are the thioamide treatment options?

Answer 9

• propylthiouracil
• methimazole

Question 10

Which thioamide blocks T4 to T3 conversion?

Answer 10

propylthiouracil

Question 11

Which thioamide is more commonly prescribed?

Answer 11

methimazole

Question 12

What are the adverse effects of thioamides?

Answer 12

• nausea/ vomiting
• rash
• agranulocytosis
• hepatitis

Question 13

What are counseling points for thioamides?

Answer 13

• take with meals, divided doses
• treat maculopapular rash with diphenhydramine
• if systemic reaction (wheals, hives, SOB), must use RAI or surgery
• if hepatitis, use RAI or surgery

Question 14

How often do you monitor levels during thioamide treatment?

Answer 14

• every 4-8 weeks until euthyroid
• every 4-6 weeks once D/C (for 3-4 months)
• yearly thereafter

Question 15

When could a thyroidectomy be indicated?

Answer 15

• obstructive symptoms from large glands
• multinodular goiter
• cancer
• medication failure
• ophthalmopathy
• pregnancy

Question 16

When are B-blockers used as a hyperthyroidism adjunct treatment?

Answer 16

• short term use to alleviate symptoms
• used in patients with HR > 90 bpm

Question 17

Which drugs are commonly used as hyperthyroidism adjunct therapies?

Answer 17

• propranolol
• metoprolol
• atenolol

Question 18

Which B-blockers should be avoided for adjunct?

Answer 18

• acebutolol
• carteolol
• penbutolol
• pindolol

Question 19

What are the calcium channel blocker adjunct treatment options?

Answer 19

• diltiazem
• verapamil

Question 20

Which drug is used to supplement T4?

Answer 20

levothyroxine

Question 21

List the branded dosage forms of levothyroxine:

Answer 21

• Tirosint (caps)
• Tirosint-SOL
• Ermeza (sol)
• Thyquidity (sol)
• Euthyrox
• Synthroid
• Levoxyl
• Unithroid Direct
• Unithroid

Question 22

Which drug is used to supplement T3?

Answer 22

Liothyronine

Question 23

What are the brand names of liothyronine?

Answer 23

• cytomel
• triostat

Question 24

Which thyroid supplement isn’t recommended?

Answer 24

Desiccated thyroid (Armour Thyroid)

Question 25

What should be the first choice in replacement therapy for all hypothyroid patients?

Answer 25

Levothyroxine (T4)

Question 26

What is the black box warning for levothyroxine?

Answer 26

weight loss - high doses may produce serious/ life-threatening effects when used with anorectic drugs (sympathomimetic amines)

Question 27

Effects of levothyroxine (T4):

Answer 27

- peripheral T4 --> T3 conversion - provides necessary hormone w/o bolus effects of T3

Question 28

Counseling tips for levothyroxine (T4):

Answer 28

- empty stomach - 60 min before breakfast or 4 hours after dinner

Question 29

What are the (levothyroxine) replacement therapy dosing guidelines for an uncomplicated adult?

Answer 29

- 1.6 mcg/kg/day - use IBW in obese patients - Average starting dose 100 mcg/day - increase by 12.5-25 mcg every 6-8 weeks

Question 30

What is the average starting dose of levothyroxine for uncomplicated adults?

Answer 30

100 mcg/day

Question 31

What are the (levothyroxine) replacement therapy dosing guidelines for an elderly (older than 65)?

Answer 31

- less than 1.6 mcg/kg/day - start at 25-50 mcg/day - increase by 12.5-25 mcg every 6-8 weeks as tolerated

Question 32

What is the typical starting dose of levothyroxine for elederly?

Answer 32

25-50 mcg/day

Question 33

What are the (levothyroxine) replacement therapy dosing guidelines for pts w cardiovascular disease/ angina?

Answer 33

- start 12.5 - 25 mcg per day - increase by 12.5 - 25 mcg every 6-8 weeks as tolerated

Question 34

What is the typical starting dose of levothyroxine for pts with CVD?

Answer 34

12.5-25 mcg/day

Question 35

What are the (levothyroxine) replacement therapy dosing guidelines for an pts with longstanding hypothyroidism (longer than a year)?

Answer 35

- dose slowly - start 12.5 - 25 mcg/day - increase by 12.5 -25 mcg every 4-6 weeks as tolerated

Question 36

What are the (levothyroxine) replacement therapy dosing guidelines for pregnant patients?

Answer 36

- may require 45% increase in dose

Question 37

What are the effects of liothyronine (T3)?

Answer 37

- rapid absorption of T3 can cause hyperthyroid symptoms - cardiac toxicities

Question 38

What are the main uses of liothyronine (T3)?

Answer 38

- short-term hormone replacement - diagnostic agent in T3 suppression test

Question 39

What is the potency of desiccated thyroid based on?

Answer 39

iodine content - unpredictable potency result in over and under supplementation

Question 40

What can cause high or fluctuating TSH despite high levothyroxine dose (>200 mcg/day)?

Answer 40

- poor adherence - drug-food interaction - drug-drug interaction

Question 41

What decreases T4 absorption?

Answer 41

- bile acid sequestrants (cholestyramine, colestipol) - Al(OH)3 antacids - ferrous sulfate - sucralfate - calcium supplements

Question 42

What increases thyroxine-binding globulin (TBG) concentration?

Answer 42

estrogen

Question 43

What increases T4 requirement?

Answer 43

- enzyme inducers: - Phenytoin (PHT) - carbamazepine (CBZ) - rifampin - phenobarbital (PB)

Question 44

What is a disease-drug interaction?

Answer 44

warfarin