Lec 3 Pituitary Tumors Flashcards
What are the 3 major types of functional pituitary tumors?
- prolactin secreting
- GH secreting
- ACTH secreting
What is MIB-1 index?
proliferation index –> predicts aggressive behavior if MIB1 >3%
What are 4 signs of hyperprolactinemia?
- galactorrhea
- menstrual abnormalities
- infertility
- decreased libido
What is usual presentation of prolactinoma in females?
small + present earlier in females b/c of abnormal menses
What is relationship level of serum prolactin and prolactinoma tumor size?
well corrleated
What levels of prolactin associated wtih macroprolactinoma?
> 150 ng/ml
What should you think if large pituitary tumor but only modest elevation in prolactin?
may be secondary to stalk compression from non-secretory tumor = lack of dopamine coming down stalk causes increase in prolactin
What is medical therapy for prolactinoma?
dopamine agonist
What are 6 potential causes of hyperprolactinemia?
- prolactinoma
- non-secretory macroadenoma w/ stalk compression
- hypothalamic lesion
- hypothyroid [high TRH stimulates prolactin]
- medication [DA antagonists = psychiatrics]
- pregnancy/nursing
What do you see histologically in pituitary adenoma
highly monomorphic cells
absence of small clusters and sinusoids
What 3 tests should you order if signs of hyperprolactinemia?
- prolactin
- TSH
- pregnancy test
What is treatment for microprolactinoma?
first line is medical = dopamine agonist
What is treatmetn for macroprolactinoma?
surgical probably
What is effect of high GH in kids vs adults?
kids –> gigantism
adults –> acromegaly
What is presentation of kid with GH secreting tmor?
gigantism
- tall height
What are signs of acromegaly?
- large tongue with deep furrows
- deep voice
- large hands and feet
- coarse facial feat.
- insulin resistance [imparied glucose tolerance]
- space between teeth
What are metabolic consequences of high GH?
- insuline resistance
- hyperinsulinemia
- glucose intolerance
What is major cause of mortality in patients with acromegaly?
cardiovascular disease
What type of tumor primarily secretes GH?
macroadenoma
What is typical etiology of GH secreting tumors?
activation point mutation in alpha subunit of Gs protein which is coupled to GHRH receptor –> persistent activation of adenylate cyclase
get cellular proliferation and increased GH secretion
What is action of somatostatin?
inhibits GH secretion
What is action of GHRH?
induces GH secretion
What is best lab test for acromegaly?
IGF1 level –> represents GH secretion over 24 hours
What is problem with random GH level as screening test?
not specific –> protein ingestion increases GH; glucose suppresses GH; diurnal variation
What do you see in glucose tolerance test w/ GH secreting tumor?
glucose is supposed to suppress GH but in GH secreting tumor –> have paradoxical increase in GH with glucose
What are 3 long term sequelae of acromegaly?
- mortality due to cardiovascular risk
- increased risk colonic polyps + colon cancer
- sleep apnea
What is treatment for acromegaly?
pituitary adenoma resection
treat with octreotide = somatostatin analog or pegvisomant = GH receptor antagonist
What do you see in TSH producing tumor?
hyperthyroidism with non-suppressed TSH [but not necessarily elevated]
What is typical manifestation of gonadotropin tumors?
usually are clinically silent b/c do not generally secrete biologically active LH/FSH
present with hypogonadism
Can you treat gonadotropin tumors medically?
nope! need surgery
How do you differentiate pituitary from ectopic cushings [non-pituitary source of ACTH]?
measure ratio of central [next to pituitary] and peripheral ACTH before and after CRH
if pituitary cushings –> higher ACTH centrally than peripherally; gradient increases after CRH
