Chapter 45: Thyroid Disorders Flashcards
Which thyroid hormone is more potent, but has a shorter half-life
T3
Free ___ is the unbound, active form that is monitored in patients with thyroid disorders
T4
Hypothyroidism = ↓ __ & ↑ __
↓ T4 & ↑ TSH
Most common cause of hypothyroidism
Hashimoto’s disease (autoimmune)
What is an uncommon, but potentially fatal complication of hypothyroidism
Myxedema coma
Initial treatment for myxedema coma
IV levothyroxine
What are s/sx of hypothyroidism
- 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
Key drugs and conditions that can cause hypothyroidism
- Remember: I TALC*
- Interferons (also hyperthyroid)
- TKIs (e.g., sunitinib)
- Amiodarone (also hyperthyroid)
- Lithium
- Carbamazepine
- Conditions: Hashimoto’s Disease
TSH level and symptoms should be monitored every __-__ weeks until levels are normal
4-6 weeks
Too high of a thyroid hormone replacement dose in elderly patients can cause what conditions
Afib and fractures
What is the drug of choice for hypothyroidism
Levothyroxine (T4)
Levothyroxine brand name
Synthroid, Levoxyl, Unithroid
Where should you check for therapeutic equivalencies of a generic brand of levothyroxine
Orange book
Full replacement dose of levothyroxine is ___ mcg/mg/day (IBW)
1.6
If known CAD, start with __-__ mcg daily of levothyroxine
12.5-25
Thyroid, desiccated (T3 & T4) brand name
Armour Thyroid
Liothyronine (T3) brand name
Cytomel
Levothyroxine PO should be taken with ___ at the same time each day for consistent absorption, at least __ min before breakfast or at ____
water
60 min
bedtime (at least 3 hours after the last meal)
Levothyroxine IV to PO ratio
0.75:1
Levothyroxine tablet colors
- 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
Which drugs can ↓ levothyroxine absorption
-Antacids and polyvalent cations containing iron, Ca, Al, or Mg multivitamins, cholestyramine, sevelamer and sucralfate –> separate doses by 4 hours
Hyperthyroidism = ↓ __ & ↑ __
↓ TSH & ↑ T4
What are the signs and symptoms of hyperthyroidism
- 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
Most common cause of hyperthyroidism
Graves’ disease (autoimmune)
Drug-induced causes of hyperthyroidism
Iodine, amiodarone, and interferons
Treatment of hyperthyroid involves drugs &
destroying part of the gland via radioactive iodine or surgery
What can be used for symptom control of hyperthyroidism
Beta-blockers
remember you are trying to slow things down
How long does it take to control symptoms with anti-thyroid meds in hyperthyroidism
1-3 months
MOA of thionamides for hyperthyroidism
Inhibit synthesis of thyroid hormones (PTU also inhibits peripheral conversion)
Which two drugs are used for hyperthyroidism
PTU and methimazole
PTU boxed warnings
Severe liver injury and acute liver failure
PTU and methimazole warnings
Hepatotoxicity, agranulocytosis, DILE
PTU and methimazole SE
GI upset
Which drug is preferred in thyroid storm
PTU
Which trimesters can methimazole be used in
2nd and 3rd (has less risk of liver toxicity)
PTU is preferred in which trimester
1st
What is the role of potassium iodide after exposure to radiation
it blocks the accumulation of radioactive iodine in the thyroid gland, thus preventing thyroid cancer
S/sx of thyroid storm
- Fever (> 103F)
- Tachycardia, tachypnea
- Dehydration
- Profuse sweating
- Agitation
- Delirium
- Psychosis
- Coma
Drug treatment for thyroid storm
PTU + SSKI or Lugol’s Solution + Propranolol + Dexamethasone + Aggressive cooling with APAP and cooling blankets
What is the safest and preferred treatment for hypothyroidism in pregnancy
Levothyroxine
Pregnant women treated with thyroid hormone replacement will require __-__% (increase or decrease) in the dose
30-50% increase
