Endo III Flashcards
thyroid hormone synthesis
in follicles
-produce T4
T3 - in peripheral tissues - more active
action of thyroid hormones
bone growth
CNS maturation
more B1 on heart
increased basal metabolic rate - more Na/K-ATPase
thyroxine binding globulin
binds most T3/T4 in blood
-only free hormone active
decreased TBG - liver failure, steroid
increased TBG - pregnancy or OCP use
5’deiodinase
convert T4 > T3 peripherally
thyroid peroxidase
oxidation and organification of iodine
also coupling of MIT and DIT
PTU
inhibit thyroid peroxidase and 5’deiodinase
methimazole
inhibit only thyroid peroxidase
wolff chaikoff effect
excess iodine - inhibit thyroid peroxidse
decreased T3 and T4 production
cushings
excess cortisol
MCC - exogenous corticosteroids
screening test cushings
24 hour free cortisol in urine
high cortisol and low ACTH
adrenal tumor - MRI confirm
high cortisol and high ACTH
test further
dexamethasone suppression test
CRH stimulation test
cushing disease
ACTH secreting pituitary adenoma
will be suppressed with high dose dexamethasone
ectopic secretion of ACTH
paraneoplastic
-will not respond to high dose dexamethasone
cushing disease results
1 suppression with high dose dexamethasone
2 increased ACTH and cortisol with CRH
ectopic secretion of ACTH
1 no suppression high dose dexamethasone
2 no increase ACTH/cortisol with CRH
adrenal insufficiency
low secretion of glucocorticoids and aldosterone
weak, fatigue, orthostatic hypotension, muscle ache, weight loss, sugar and salt craving
acute primary adrenal insufficiency
waterhouse friedrichsen
-adrenal hemorrhage with septicemia or shock
chronic primary adrenal insufficiency
addison disease
arophy or destruction by disease
metyrapone test
metyrapone - block convestion 11-deoxycortisol > cortisol
normal response - low cortisol and high ACTH
with adrenal insufficiency - see no rise in ACTH
primary adrenal insufficiency
hypotension
hyperK
metabolic acidosis
skin and mucosa hyperpigment - MSH - byproduct of increased ACTH production from POMC
secondary adrenal insufficiency
decreased pituitary ACTH production
no hyperpigmentation
no hyperK - aldosterone synthesis preserved
tertiary adrenal insufficiency
chronic steroid use
-aldosterone ok
neuroblastoma
adrenal medulla tumor in children
-from neural crest
has homer wright rosette
abdomnal mass - cross midline
HVA and VMA elevated
bombesin and neuron specific enolase positive
neuroblastoma genetic
associated with overexpression N-myc
pheochromocytoma
MC tumor adrenal medulla in adults
from chromaffin cells - neural crest
see catecholamines and metanephrines in urine
rule of 10s
with pheochromocytoma
-10 % malignant, B/L, extra-adrenal, calcify, kids
episodic HTN
pheochromocytoma
associations with pheochromocytoma
NF1
VHL
MEN 2A
MEN 2B
tx pheochromocytoma
irreversibla a-antagonist
-phenoxybenzamine
followed by B-blocker
a-blockade first - avoid HTN crisis
hypothyroid
less reflexes
hypercholesterol - decreased LDL receptors
hyperthyroid
more reflexes
hypocholesterol - increased LDL receptors
hashimotos
autoimmune - anti-thyroid peroxidase Abs
-also - antimicrosomal and anti-thyroglobulin Abs
with HLA-DR5
enlarged nontender thyroid
risk with hashimotos
non-hodgkin lymphoma
early hyperthyroid in hashimotos
due to follicular rupture - thyrotoxicosis
hurthle cells
hashimotos - lymphoid aggregate - germinal centers
cretinism
congenital hypothyroid
pot belly, pale, puffy face, protruding umbilicus, protuberant tongue, poor brain development
de quervain thyroiditis
subacute
follow flu-like illness
granuloma inflammation
jaw pain - very tender thyroid
riedel thyroiditis
thyroid - replace with fibrous tissue
manifestation of IgG4 systemic disease
fixed hard painless goiter
