020415 hypothyroidism in adult Flashcards
most common hypothyroidism
primary hypothyroidism (Hashimoto’s thyroiditis)
chronic lymphocytic thyroiditis
Hashimoto’s thyroiditis
mechanism of chronic lymphocytic thyroiditis
sensitization of host’s own lymphocytes to various thyroidal antigens (thyroblogulin, thyroid peroxidase, TSH receptor)
cytokine release and inflam ultimately result in glandular destruction
differential diagnosis of hypothyroidism that’s primary
chronic lymphocytic thyroiditis (Hashimoto’s)
thyroidectomy
reversible autoimmune thyroiditis (silent and postpartum thyroiditis)
thyroid irradiation
infilatrative and infectious dis
thyroid dysgenesis (no formation of thyroid)
iodine deficiency
iodine excess (Wolff Chaikoff effect)–thyroid shuts down
drugs
differential diagnosis of secondary/tertiary (central) hypothyroidism
tumors
trauma
infiltrative diseases (sarcoidosis, hemochromatosis)
drugs
inactivating mutations in genes that code for proteins involved in hypothalamic-pituitary-thyroid axis
clinical features of hypothyroidism
losing outer 1/3 of eyebrow periorbital puffiness thickening of skin myxedema affects just about everything
in severe, there’s myxedema (bulging of eyes and pretibial swelling)
how to diagnose hypothyroidism?
do first: serum TSH (much more sensitive than thyroid hormone)
if TSH is abnormal, or if there is a high clinical suspicion for a central disease process, free T4 is ordered to further characterize the thyroid condition. thyroid antibodies often tested.
in secondary/tertiary hypothyroidism, what are the levels of TSH and free T4, T3?
TSH: low or normal
free T4, T3: low
half life of levothyroxine vs liothyronine (T3)
T4 has half life of 7 days
T3: 1 day
myxedema coma
severe hypothyroidism
multiorgan dysfxn, serious hypothermia, hypoventilation, hypotension, and CNS signs
