Chapter 45: Thyroid Disorders

Question 1

Which thyroid hormone is more potent, but has a shorter half-life

Answer 1

T3

Question 2

Free ___ is the unbound, active form that is monitored in patients with thyroid disorders

Answer 2

T4

Question 3

Hypothyroidism = ↓ __ & ↑ __

Answer 3

↓ T4 & ↑ TSH

Question 4

Most common cause of hypothyroidism

Answer 4

Hashimoto’s disease (autoimmune)

Question 5

What is an uncommon, but potentially fatal complication of hypothyroidism

Answer 5

Myxedema coma

Question 6

Initial treatment for myxedema coma

Answer 6

IV levothyroxine

Question 7

What are s/sx of hypothyroidism

Answer 7

• Cold intolerance/sensitivity
• Dry skin, coarse hair or loss of hair
• Fatigue; weakness
• Muscle cramps; myalgia
• Voice changes
• Constipation
• Weight gain
• Goiter
• Depression; memory & mental impairment
• Bradycardia
• Menorrhagia

Question 8

Key drugs and conditions that can cause hypothyroidism

Answer 8

• Remember: I TALC*
• Interferons (also hyperthyroid)
• TKIs (e.g., sunitinib)
• Amiodarone (also hyperthyroid)
• Lithium
• Carbamazepine
• Conditions: Hashimoto’s Disease

Question 9

TSH level and symptoms should be monitored every __-__ weeks until levels are normal

Answer 9

4-6 weeks

Question 10

Too high of a thyroid hormone replacement dose in elderly patients can cause what conditions

Answer 10

Afib and fractures

Question 11

What is the drug of choice for hypothyroidism

Answer 11

Levothyroxine (T4)

Question 12

Levothyroxine brand name

Answer 12

Synthroid, Levoxyl, Unithroid

Question 13

Where should you check for therapeutic equivalencies of a generic brand of levothyroxine

Answer 13

Orange book

Question 14

Full replacement dose of levothyroxine is ___ mcg/mg/day (IBW)

Answer 14

1.6

Question 15

If known CAD, start with __-__ mcg daily of levothyroxine

Answer 15

12.5-25

Question 16

Thyroid, desiccated (T3 & T4) brand name

Answer 16

Armour Thyroid

Question 17

Liothyronine (T3) brand name

Answer 17

Cytomel

Question 18

Levothyroxine PO should be taken with ___ at the same time each day for consistent absorption, at least __ min before breakfast or at ____

Answer 18

water
60 min
bedtime (at least 3 hours after the last meal)

Question 19

Levothyroxine IV to PO ratio

Answer 19

0.75:1

Question 20

Levothyroxine tablet colors

Answer 20

• Remember: Orangutans Will Vomit On You Right Before They Become Large Proud Giants*
• 25 mcg = orange
• 50 mcg = white (no dye)
• 75 mcg = violet
• 88 mcg = olive
• 100 mcg = yellow
• 112 mcg = rose
• 125 mcg = brown
• 137 mcg = turquoise
• 150 mcg = blue
• 175 mcg = lilac
• 200 mcg = pink
• 300 mcg = green

Question 21

Which drugs can ↓ levothyroxine absorption

Answer 21

-Antacids and polyvalent cations containing iron, Ca, Al, or Mg multivitamins, cholestyramine, sevelamer and sucralfate –> separate doses by 4 hours

Question 22

Hyperthyroidism = ↓ __ & ↑ __

Answer 22

↓ TSH & ↑ T4

Question 23

What are the signs and symptoms of hyperthyroidism

Answer 23

• Heat intolerance or increased sweating
• Weight loss
• Agitation, nervousness, irritability, anxiety
• Palpitations and tachycardia
• Fatigue and muscle weakness
• Frequent bowel movements or diarrhea
• Insomnia
• Tremor
• Thinning hair
• Goiter
• Exophthalmos, diplopia
• Light or absent menstrual periods

Question 24

Most common cause of hyperthyroidism

Answer 24

Graves’ disease (autoimmune)

Question 25

Drug-induced causes of hyperthyroidism

Answer 25

Iodine, amiodarone, and interferons

Question 26

Treatment of hyperthyroid involves drugs &

Answer 26

destroying part of the gland via radioactive iodine or surgery

Question 27

What can be used for symptom control of hyperthyroidism

Answer 27

Beta-blockers | remember you are trying to slow things down

Question 28

How long does it take to control symptoms with anti-thyroid meds in hyperthyroidism

Answer 28

1-3 months

Question 29

MOA of thionamides for hyperthyroidism

Answer 29

Inhibit synthesis of thyroid hormones (PTU also inhibits peripheral conversion)

Question 30

Which two drugs are used for hyperthyroidism

Answer 30

PTU and methimazole

Question 31

PTU boxed warnings

Answer 31

Severe liver injury and acute liver failure

Question 32

PTU and methimazole warnings

Answer 32

Hepatotoxicity, agranulocytosis, DILE

Question 33

PTU and methimazole SE

Answer 33

GI upset

Question 34

Which drug is preferred in thyroid storm

Answer 34

PTU

Question 35

Which trimesters can methimazole be used in

Answer 35

2nd and 3rd (has less risk of liver toxicity)

Question 36

PTU is preferred in which trimester

Answer 36

1st

Question 37

What is the role of potassium iodide after exposure to radiation

Answer 37

it blocks the accumulation of radioactive iodine in the thyroid gland, thus preventing thyroid cancer

Question 38

S/sx of thyroid storm

Answer 38

- Fever (> 103F) - Tachycardia, tachypnea - Dehydration - Profuse sweating - Agitation - Delirium - Psychosis - Coma

Question 39

Drug treatment for thyroid storm

Answer 39

PTU + SSKI or Lugol's Solution + Propranolol + Dexamethasone + Aggressive cooling with APAP and cooling blankets

Question 40

What is the safest and preferred treatment for hypothyroidism in pregnancy

Answer 40

Levothyroxine

Question 41

Pregnant women treated with thyroid hormone replacement will require __-__% (increase or decrease) in the dose

Answer 41

30-50% increase