2 - Anterior Pituitary 1 Flashcards
which pituitary hormones are grouped together by differentiation pathways?
GH and prolactin
TSH and LH/FSH
ACTH and melanotropes
common alpha subunit is shared by what hormones?
TSH, LH, FSH, beta-HCG
size cutoff btwn micro and macroadenoma in pituitary
1 cm
4 MC pituitary adenoma cell types / secretion types
35% prolactin
28% “non functioning” (alpha subunit)
17% GH
9% ACTH
visual field defect assoc w/ pituitary tumor
superior temporal quadrantanopsia or temporal hemianopsia
sx of hyperprolactinemia
women: galactorrhea, amenorrhea
men: dec libido, impotence, rarely have galactorrhea
causes of hyperprolactinemia (fairly general)
PREGNANCY (must r/o before working up for prolactinoma)
hypothyroidism (TRH stimulates prolactin release)
prolactinoma
other pituitary masses interfering w/ DA inhibition
cosecretion w/ GH (ex in acromegaly)
anti dopaminergic drugs
chronic renal failure
Hook effect
immunoassays can give false negs if levels of target are too high - abs get covered by so much antigen that nothing can agglutinate
only pituitary adenoma where surg is not considered first line tx
prolactinoma
tx of prolactinoma
dopamine agonists - bromocriptine (used in pregnancy but causes nausea and orthostasis), cabergoline (better tolerated)
cabergoline
DA agonist used for hyperprolactinemia
normal stimuli for GH secretion
diurnal - inc during sleep
physical activity and emotional stress stimulate it
what molecule mediates most growth effects of GH?
insulin like growth factor 1 (IGF-1)
GH effects independent of IGF1
glucose homeostasis (insulin resistance), Ca metab (inc bone density), lipolysis
cause of GH excess
mostly sporatic adenomas
causes of sx in GH excess
neuropathy
enlarged visceral organs (heart important here)
glucose intolerance
how to dx acromegaly
single serum GH > 100 ng/ml (rarely done b/c often dont catch it)
elevated IGF-1 (longer half life so more sensitive)
medical therapy for acromegaly
somatostatin analogues - octreotide, etc
pegvisomant (GH-R antagonist)
dopamine agonist (bromocriptine, cabergoline)
complications of acromegaly
inc mortality rate (2-3x)
often CV problems, respiratory, inc risk of malignancy
can develop overt DM
McCune Albright
inherited cause of GH pituitary adenoma
G protein subunit mutation
cafe au lait spots, precocious puberty, acromegaly/gigantism, thyrotoxicosis
Carney Complex
inherited cause of GH pituitary adenoma
PKA type 1 regulatory subunit problem
spotty skin pigmentation and blue nevi, cardiac myxomas, schwannomas, testicular/ovarian tumors
Multiple endocrine neoplasia (MEN 1)
AD inheritance
menin gene mutation (tumor suppressor)
3 Ps - pituitary adenoma (mostly prolactin, next MC is GH), parathyroid hyperplasia, pancreatic neuroendocrine tumors (mostly gastrinoma, maybe insulinoma)
