Week 13 - Hypothyroidism Flashcards
What is hypothyroidism? (4)
- insufficient thyroid hormone
- Most often autoimmune
“Hasimoto’s Thyroiditis” - affects ~2% of population
Why hypothyroidism, symptoms are related to decreased _____. (2)
Metabolism
think “slow”
When do symptoms for hypothyroidism occur?
- unless due to thyroidectomy or antithyroid tx, sx usually insidious for months to years
What are the symptoms of hypothyroidism? (7)
- vital sign changes
- goitre
- Fatigue, lethargy
- constipation
- weight gain (will not be hungry or eat a lot, but you will gain weight)
- Cold intolerance, susceptible to infection
- mental changes
heart loses contractility force
Myxedema may be displayed with hypothyroidism. What is it? (3)
- Those with severe, longstanding hypothyroidism
- thickened, non-pitting edematous changes to the soft tissues
- causes puffiness, periorbital edema, masklike effect
basically the thyroid hormone is not there to tell the cells to use energy
What is a myxedema coma? (3)
- medical emergency
- Gradual or sudden advancement in sluggishness, drowsiness, and lethargy of hypothyroidism progresses to impaired LOC (coma)
- May need ventiliator
What is myxedema precipitated by? (4)
Stress
- infection
- drugs (narcotics, tranqs, barbs)
- exposure to cold and trauma
What happens to temperature, BP and ventilation with myxedema coma? (3)
- decreased temperature
- decreased BP
- Hypoventilation
What is the tx to myxedema coma? (2)
- support vital functions
- hormone replacement
How is hypothyroidism diagnosed? (4)
- History and physical exam
- Blood test for TSH and T4
- May also look for TPO antibodies against thyroid
- May have high cholesterol and triglycerides, anemia and increased creatine kinase
We would see an increase in TSH and decrease in T3 and T4
THINK: Why does hypothyroidism cause an increase in TSH, but a decrease in T3 and T4?
In primary hypothyroidism, the thyroid produces insufficient amounts of T3 and T4, which leads to loss of negative feedback inhibition, and increased production of TSH from the anterior pituitary
What medications are used to treat hypothyroidism?
levothyroxine (synthroid)
What is levothyroxine used to treat? (3)
- primary hypothyroidism
- myxedema coma
- simple goitre
What are some considerations when administering levothyroxine? (2, 4)
- Oral absorption is reduced by food
- should be taken on an empty stomach in the morning (30-60 minutes before breakfast) - Highly protein bound (99.7%)
- half life is ~7 days, which allows for once a day dosing, but takes about 1 month to reach plateau
On it forever!!
What are the adverse effects of levothyroxine? (3)
- rare with appropriate dosing
- acute overdose can cause thyrotoxicosis
- Chronic overdose can lead to accelerated bone loss and increased risk of afib (esp. in older adults)
