pituitary Flashcards
what are the hormones of the ant pit and what are they stimulated by
GHRH - GH
dopamine - NEG regs prolactin
TRH - TSH and prolactin
LHRH - LH FSH
CRH - ACTH
visual field defect with pit macroadenoma (>1cm)
bitemporal hemianopia
macular spared
tested with humphrey’s 30-2 test
C - optic chiasm
I - blood vessels
asterix - air
pit macroadenoma
All around carotid artery - cant have surgery for this
dx?
prolactinoma
always prolactinoma if >6000
what ix should be done if suspecting prolactinoma
pit function test - ensure the pit gland responds to a metabolic stress (ACTH and GH)
Prolactinoma press on other cells and stop them working - so want to do pit func testing
ACTH will kill you if you haevnt got enough
Gold standard to know that the pit is working
Can just measure morning cortisol - because if high then don’t need stress test
how do you do a pit function test
trying to raise the ant pit hormones
make hypoglycaemic (stress -> CRH and GHRH release -> ACTH and GH), give LHRH and TRH (-> TSH and prolactin)
fast pt
weigh them
give IV insulin, TRH, LHRH
pt will have warm flush and vomit
measure blood glucose, cortisol, GH, LH, FSH, TSH and prolactin everyt 30mins for 1 hr and basal thyroxine
check glucose, cortisol and GH up to 120mins
caution with doing pit function test
hypoglycaemia can be dangerous - Make sure no heart problems and ECG normal -> MI
Make sure not epileptic will -> fit
when hypo - first SNS activation ie sweaty and palpitations
when <1.5mM -> neuroglycopenia - aggressive and confused
for test need <2.2mM
what do you do if severe hypoglycaemia occurs
rescue pt with 50ml of 20% dextrose - make sure line already in place because can be difficult to give to an aggressive pt
normal response to pit function test
Glucose Drop with insulin and rises as hormones come up
cortisol reach 450
GH reach 10
if v insulin resistant might need more insulin to get it to <2.2
describe the result
No GH, cortisol, LH, FSH, TSH rise
And prolactin stays high
prolactinoma
what do you need to replace urgently if these are the results of the pit function test - then what else do you need to replace?
hydrocortisone - urgently
thyroxine
oestrogn
GH
rx for high prolactin
cabergoline or bromocriptone (dopamine agonist)
non-functioning adenoma
press on stalk -> pit failure
prevent dopamine reaching pit -> hyperprolactinaemia
mx - hydrocortisone, thyroxine, oestrogen, GH and maybe cabergoline
(can give pred instead of hydrocortisone - longer half life, can give once daily)
Acromegaly
Thyroxine is low - tumour caused hypothyroidism
TSH is low
Failure of pit gland except GH - so acromegaly
adrenals
