Physiology of the Pituitary Gland Flashcards
what 2 chemicals are synthesised in the body of the nerve cells within the hypothalamus?
ADH
oxytocin
where are stimulating and inhibiting hormones released from?
body of the nerve cells of the hypothalamus
how many hormones does the anterior pituitary gland secrete?
5
what is thyrotropin?
TSH
what does cortisol do?
regulates BGLs
increases fat in the body
helps to defend the body against infection
what 2 hormones does gonadotropin releasing hormone stimulate the release of ?
luteinizing hormone
follicle stimulating hormone
what is the releasing hormone for GH?
growth hormone releasing hormone
what is the only hormone to be inhibited and not stimulated?
prolactin
what hormone from the pituitary inhibits the release of prolactin?
dopamine
what 2 hormones are released from the posterior pituitary?
vasopressin
oxytocin
is ACTH released from the pituitary or hypothalamus?
pituitary
what hormone stimulates production of ACTH?
CRH
peripheral sex hormones?
testosterone
oestradiol
which hormone has a direct effect on tissues?
GH
what can be affected when pituitary tumours grow up the way?
can hit optic chiasma
what happens when the optic chiasma is affected by a tumour
lose temporal vision
what can be hit if a pituitary tumour grows downwards?
sphenoid sinus
what is done in an insulin stress test?
make them go hypo to force the hypothalamus into secreting hormones
when would the patient have a positive insulin stress test?
in pituitary problems
when would you do a prolonged glucagon test instead of an insulin stress test?
epilepsy
over 60
heart disease
normal cortisol level?
over 500
normal GH level?
> 7ug/l
is the water deprivation test a stimulation or suppression test?
stimulation
what is a pituitary tumour <1cm called?
microadenoma
what is a pituitary tumour >1cm called?
macroadenoma
what can a pituitary tumour hit if it grows laterally?
cranial nerves 4, 3, 6
will a non functioning pituitary adenoma cause hypo or hyper hormone production?
hypo
name the 2 fields of the eye?
nasal
temporal
non drug causes of a raised prolactin?
breast feeding pregnancy stress sleep hypothyroidism stalk lesion prolactinoma
does prolactinaemia present early in women or men?
women
what do women get in prolactinoma that men dont get?
menstrual irregularity
leaking of milk from breast
what do men get in prolactinoma that women dont get?
impotence
visual field problems
headache
anterior pit malfunction
investigations for prolactinoma?
- MRI pituitary
- visual fields
- PFTs if other hormones affected
best treatment for prolactinoma?
NOT surgery
cabergoline PO 2x pw
cause of acromegaly?
GH excess
clinical presentation of acromegaly?
giant thickened soft tissues hypertension CV problems sleep apnoea headaches diabetes colon cancer
are the headaches in acromegaly caused by the tumour or vascular problems?
vascular problems
how is acromegaly measured?
IGF1 levels
GTT
why is GTT measured in acromegaly?
glucose inhibits GH
is IGF1 elevated or low in acromegaly?
elevated
1st line treatment for acromegaly?
pituitary surgery
2nd line treatment for acromegaly?
radiotherapy
3rd line treatment for acromegaly?
somatostatin analogue
short term side effects of somatostatin analogues?
flatulence
diarrhoea
abdo pain
cause of cushings syndrome?
excess cortisol
what actually causes the symptoms of cushings syndrome?
protein loss from tissues
what chemicals other than cortisol are in excess in cushings?
androgens
mineralocorticoid
what condition causes frontal balding in women?
cushings
what condition’s patients are described as a lemon on matchsticks?
cushings
1st line screening test for cushings?
overnight 1mg dexamethasone suppression test PO
what cortisol level in the morning would indicate a normal dexamethasone test?
<50
what would you expect to happen when given dexamethasone test?
cortisol to lower
definitive test for cushings?
2 day 2mg dexamethasone suppression test
what form of steroid is the worst for causing cushings?
inhaled
topical
where does ectopic cushings come from?
thymus
lungs
pancreas
would you expect ACTH levels to be high, normal low in pituitary tumours?
high, around 300
what cushings cause would cause the highest ACTH level?
> 300
treatment for pituitary cushings?
hypophysectomy
bilateral adrenalectomy
treatment for adrenal cushings?
adrenalectomy
treatment for ectopic cushings?
remove source OR
bilateral adrenalectomy
what drug treatment can be given for cushings if other treatment fails?
metyrapone
ketoconazole
somatostatin analogue
causes of hypopituitarism?
lung/breast mets brain tu,oir TB sarcoidosis polyarteritis trauma iatrogenic infection
clinical presentation of hyperpituitarism?
menstrual irregularities gynaecomastia infertility abdominal obesity dry skin and hair
how much thyroxine should you give in hypopituitarism?
100-150mcg
what are all the drugs you need to give for hypopituitarism?
thyroxine hydrocortisone ADH GH HRT/oest/prog pill OR testosterone
causes of cranial diabetes insipidus?
DIDMOAD
trauma
tumour
what is the only hormone that wont go down in hypopituitarism?
prolactin
what test should you do for cranial diabetes insipidus?
water deprivation test