Pituitary Flashcards
sx from tumor pressing superior to pituitary
optic chiasm –> CN II - visual field cuts and blindness
pituitary stalk and hypothalamus –> messed up delivery of hypothalamic releasing factors, ADH, satiety centers
sella turcica and tentorium sella –> headache, destruction of pituitary tissue
sx from tumor pressing inferior to pituitary
sphenoid sinus –> CSF rhinorrhea and risk of meningitis
sx from tumor pressing lateral to pituitary
cavernous sinus compression of CN III, IV VI –> ocular palsies
temporal lobe –> temporal lobe epilepsy
menopause - what happens
ovaries involute. pituitary still makes LH and FSH but ovaries don’t respond. high LH and FSH b/c no estradiol and progesterone for negative feedback.
somatostatin
neg feedback to pituitary in thyroid axis and growth hormone axis
where is IGF1 made?
liver
prolactin axis control
tonic inhibition by dopamine from hypothalamus
TRH can swim prolactin if produced in gross excess
glycoprotein hormones
Pituitary hormones: FSH, LH, TSH
hCG
all have same alpha subunit, but unique beta subunits
glycosylation req for function
pituitary apoplexy
acute bleeding into pre-existing adenoma –> headache, visual disturbances, acute panhypopituitaryism
causes of acromegaly
somatic mutation in g protein of GH-secreting cells of pituitary
tx of acromegaly
surgery or radiation
med therapy:
- dopamine antagonist
- long-acting somatostatin analog (octreotide)
acromegaly and T2D
increased IGF-1 w/ ANTI-insulin effects –> insulin resistance –> resembles T2D
ddx hyperprolactinemia
hypothalamic disease
pituitary disease: prolactinoma, mechanical compression
primary hypothyroidism (TRH –> upreg prolactin)
neurally mediated
drugs: antipsychotics, antidepressants, opiates, dopaminergic antagonists
prolactin and gonadal function
prolactin INHIBITS GnRH secretion and LH effects
why and how tx prolactinoma
why: infertility, mass effect, osteoporosis
how: surgery, radiation, dopamineric agonists –> shrinkage
draw the PROP1/PIT1 scheme
see notes
IGFBP-3
binding protein. growth hormone dependent. used clinically as a marker for GH deficiency
thyroid hormone and growth
hypothyroidism –> impaired GH release, delayed bone maturation
hyperthyroidism –> accelerated linear growth and bone maturation
gonadal steroids and growth
estrogen + testosterone spur linear growth in pubertal growth spurt
bone maturation is due to estrogens
what is responsible for fetal growth?
most rapid stage of growth
not GH dependent, dependent on maternal placental factors
what is responsible for growth in infancy?
transition towards pituitary depend growth and IGF-1
what is responsible for growth in childhood?
sensitive to growth hormone and thyroid hormone
not sex steroids
what is responsible for pubertal growth?
growth spurt due to sex hormones
- direct effect on linear growth
- increase production of growth hormones and IGF-1
GH deficiency
decreased linear growth
hypoglycemia in infancy (b/c GH is counter-reg to insulin)
