013015 anterior pituitary Flashcards
the pituitary sits close by to
optic chiasm cavernous sinus (which holds common carotid artery, cranial nerves)
what controls pituitary prolactin release?
dopamine (negative effect on prolactin release)
TRH (thyrotropin-releasing hormone), estrogen, vasopressin, vasopressin, vasoactive intestinal polypeptide (VIP, oxytocin, epidermal growth factor stimulate prolactin production
how do you diagnose hyperprolactinemia?
single measurement of increased serum prolactin
a serum prolactin concentration over 250 ng/ml suggests
prolactinoma (prolactin secreting pituitary tumor) some drugs (metoclopramide and risperidone-dopamine antagonists)
microprolactinomas can also have prolactin in 100-250 ng/ml range
mild to moderate hyperprolactinemia (25-100 ng/ml)
hyperprolactinemia due to infundibular stalk compression
hyperprolactinemia due to infundibular stalk compression is
presence of a larger pituitary mass, more likely to be due to nonprolactin-secreting tumor with infundibular stalk compression and inhibition of dopamine transport to the lactotroph
physiological and other causes of hyperprolactinemia
pregnancy
lactation
exercise, sleep, stress–won’t pick up on blood test
meds
pathological causes of hyperprolactinemia
hypothalamic-pituitary stalk DAMAGE:
(infiltrative disorders, irradiation to brain, trauma, tumors)
pituitary causes:
- prolactinomas (cause HIGHEST levels of prolactin-over 250. all the rest on here cause mild to moderate increase)
- macroadenoma (compression of infundibular stalk)
- lymphocytic hypophysitis (autoimmune)
clinical presentation of hyperprolactinemia
young women-menstrual irregularities galactorrhea, infertility
men-decrease in libido, erectile dysfxn
hypogonadism
if prolactinoma–in women, it usually a microadenoma due to early presentation. in men and postmenopausal women, it’s usually macroprolactinoma
how to tx hyperprolactinemia
dopamine agonists–activate D2 receptors:
- -cabergoline-preferred (longer half life, high affinity and selectivity)
- -bromocriptine (for pts undergoing fertility induction that also have hyperprolactinemia)
initial tx for macroprolactinomas that have caused compromise of vision, neurologic deficits and pituitary fxn
dopamine agonists
what factors control GH secretion?
somatostatin (-)
GHRH (+)
IGF-1 (-) (its synthesis occurs due to GH, and it negatively feedbacks on GH)
clinical features of acromegaly
headache enlarged lips, nose, tongue frontal bossing pronathism thickened skin hepatomegaly arhtorpathy carpal tunnel (entrapment of nerves)
how to dyou diagnose acromegaly
measure serum IGF-1 (in excess in acromegaly)
oral glucose tolerance test (normally glucose suppresses GH levels)
tx of acromegaly
transphenoidal surgery (curative for many microadenomas)
radiation therapy (takes 10 yrs to normalize GH levels, so meanwhile will use drug therapy)
drug therapy:
- STOMATOSTAIN RECEPTOR LIGANDS (octreotide, lanreotide)
- cabergoline (less effective)
- pevisomant (a GH receptor antagonist-only used when pt on max doses of somatostatin)
