notes

Question 1

drugs that can cause hypothyroidism

Answer 1

amiodarone
carbamazepine
eslicarbazepine
oxcarbazepine
interferons
lithium
phenytoin
TKIs especially sunitinib

Question 2

What is the most common cause of hypothyroidism?

Answer 2

Hashimoto’s disease - an autoimmune disease

Question 3

If left untreated, what life threatening emergency can occur it hypothyroidism?

Answer 3

myxedema coma

Question 4

diagnosis of hypothyroidism?

Answer 4

low free T2

high TSH

Question 5

monitoring parameter in hypothyroidism

Answer 5

TSH q4-6 weeks until levels are normal then q4-6 months rarely use T4

Question 6

Too high doses of thyroid replacement hormone can lead to what in elderly pts?

Answer 6

atrial fibrillation and fractures

Question 7

how to treat hypothyroidism in pregnancy

Answer 7

levothyroxine is safe in pregnancy and aggressive treatment is warranted (30-50% increase in dose)

Question 8

What is the drug of choice in hypothyroidism?

Answer 8

levothyroxine (T4) - use same formulation

Question 9

What are other supplemental medications used in hypothyroidism?

Answer 9

liothyronine (T3, Cytomel, Triostat)
dessicated thyroid (T3 & T4, Armour Thyroid)

Question 10

How should levothyroxine be taken?

Answer 10

60 minutes before breakfast or 3 hours after dinner at bedtime. Should be taken consistently.

Question 11

What is the dose of levothyroxine in pts w/ CAD?

Answer 11

12.5 to 25 mcg/day

Question 12

warnings levothyroxine

Answer 12

decrease dose in CAD and decreased BMD

Question 13

levothyroxine brand

Answer 13

Synthroid, Levoxyl, Tirosint, Unithroid

Question 14

SE levothyroxine

Answer 14

if euthyroid, no symptoms. Hyperthyroid symptoms if too high of dose

Question 15

drugs that decrease levothyroxine absorption

Answer 15

space out by 4 hours:
aluminum antacids
calcium
iron
magnesium
cholestyramine
sucralfate
sevelamer
vitamins containing ADEK, iron, folate
orlistat

space out by 3 hours:
Kayexelate

space out by 2 hours:
lanthanum

Question 16

drugs that decrease thyroid hormone levels

Answer 16

estrogen
SSRIs
hepatic inducers

Question 17

drugs that decrease conversion of T4 to T3

Answer 17

amiodarone
propylthiouracil
steroids

Question 18

thyroid hormones are highly protein bound. drugs that can cause protein binding displacement

Answer 18

NSAID
salicylates >2g/day
phenytoin
heparin

Question 19

levothyroxine and warfarin

Answer 19

can increase PT/INR

Question 20

levothyroxine and digoxin

Answer 20

decrease digoxin levels

Question 21

levothyroxine and theophylline

Answer 21

decrease theophylline levels

Question 22

levothyroxine and antidiabetic agents

Answer 22

decrease antidiabetic agent levels

Question 23

levothyroxine tablet colors

Answer 23

Orangutans Will Vomit On You Right Before They Become Large, Proud Giants

Question 24

what is IV:PO levothyroxine ratio

Answer 24

0.75:1

Question 25

Liotrix brand | whats in it?

Answer 25

Thyrolar contains levothyroxine and liothyronine in a 1:4 ratio

Question 26

What is the most common cause of hyperthyroidism?

Answer 26

Grave's disease

Question 27

which drugs can cause hyperthyroidism?

Answer 27

iodine amiodarone interferon (amiodarone and interferon can also cause hypothyroidism)

Question 28

What agent is typically used first for symptom control in hyperthyroidism?

Answer 28

beta blockers to control palpitations, tachycardia, tremors

Question 29

initially when treating hyperthyroidism with drugs, how long does it take for symptom control?

Answer 29

1-3 months on a high dose and then dose reduce to prevent hypothyroidism

Question 30

What are thionamides?

Answer 30

they are used in hyperthyroidism to prevent oxidation of iodine. propylthiouracil also prevents conversion of T4 to T3 in the periphery.

Question 31

pregnancy and thionamides

Answer 31

1st trimester: PTU | 2 and 3 trimester: switch to methimazole

Question 32

brand methimazole

Answer 32

Tapazole

Question 33

BW PTU

Answer 33

acute hepatic failure, severe liver injury

Question 34

SE methimazole, PTU

Answer 34

``` GI upset (take w/ food to decrease) hepatitis, agranulocytosis ```

Question 35

which thionamide is preferred in thyroid storm?

Answer 35

PTU

Question 36

Iodides used in hyperthyroidism

Answer 36

Lugol's solution - potassium iodide and iodine | SSKI, Thyroshield - saturated solution potassium iodide

Question 37

why is potassium iodide recommended right after thyroid radiation?

Answer 37

It blocks the accumulation of radioactive iodine therefore preventing thyroid cancer

Question 38

Drug treatment in Thyroid storm

Answer 38

``` PTU 500-1000mg LD followed by 250mg q4h inorganic iodide w/ Lugol's or SSKI beta blocker systemic steroids aggressive cooling with acetaminophen and cooling blankets supportive therapy ```

Question 39

what is the starting dose of levothyroxine?

Answer 39

1. 6 mcg/kg/day | 12. 5 to 25 in CAD

Question 40

PTU and warfarin

Answer 40

can decrease INR