pituitary tumours Flashcards
what are the 5 types of anterior pituitary cells
somatotrophs lactotrophs thyrothrophs gonadotrophs corticotrophs
what can a somatotroph tumour cause
acromegaly
what can a lactotroph tumour cause
prolactinoma
what can a thyrotroph tumour cause
tshoma (very unusual)
what can a gonatroph tumour cause
gonadotrophinoma(unusual)
what can a corticotroph tumour cause
cushings disease/ corticotroph adenoma
how to classify pituitary tumours
- radiological:
size: microadenoma <1cm
macroadenoma>1cm
sella/suprasella
compressing optic chiasm?
invading cavernous sinus
functioning or not?: secretions
benign/malignant:
what does hyperprolactinaemia effect the gonads
prolactin binds to prolactin receptors on kisspeptin neurone
kisspeptin release is inhibited
gnrh neurones are not able to travel down hypophyseal portal circulation
decrease in downstream gnrh,lh,fsh,t,oest
causes oligo amennorrhoea
low libido
infertility
osteoporosis
(symptoms of secondary hypogonadism)
what are prolactinomas
commonest functioning pituitary adenoma
>5000 mu/l serum prolactin
presntation of prolactinoma
menstrual disturbance erectile dysfunction reduced libido galactorrhoea subfertility
other causes of elevated prolactin
pregnancy/breastfeeing
stress/exercise/seizures/venepuncture
pathological - hypothyroidism,pcos,chronic renal failure
lactrogenic - anti psychotics, ssris, antiemetics, high dose oestrogen, opiates
what is a macroprolactin
sticky prolactin
polymeric form of prolactin - antigen antibody complex of prolaction and igG
recorded as elevated prolactin
what can the stress of venepuncture cause
elevated prolactin
use cannulated prolactin series instead
once confirmed prolactinoma what should you do
organise pituitary mri
treatment of prolactinoma
medical!
dopamine recpetor agonist - Cabergoline
safe in preg
shrinks prolactinoma
what are some symptoms/sign of acromegaly
sweatiness headache macroglossia prominent nose large jaw - prognathism increased hand and feet size snoring/obstructive sleep apnoea hypertension impaired glucose/ diabetes mellitus (increased cvd)
what are the mechanisms of GH?
direct effects - binds to receptors on bone
gh also travels to liver to screte igf1 and igf2(fetal growth)
diagnosis of acromegaly
gh is pulsatile
can do an igf1 test - elevated
then oral glucose tolerance test- in acromegaly gh increases after oral glucose load
treatment of acromegaly
trans sphenoidal pituitary surgery can use medical beforehand to shrink tumour somatostatin analogues - octreotide dopamine agonists e.g cabergoline aim is to dcrease cvd risk radiotherapy?
what are the signs and symptoms of cushins
red cheeks fat pads moon face easil bruising depression impaired glucose tolerance
what is cushings syndrome cause by?
- excess of cortisol or other glucocorticoid
acth dependent:
adenoma of corticotrophs - cushings disease
ectopic acth - lung cancer
acth independent:
steroid use e.g in asthma ,rheum arth
adrenal ademona/carcinoma
how to investigate cushings disease
elevation of 24h urine free cortisol
salivary/blood test at night
failure to supress cortisol after dexamethasone
after confirming hypercortisolism what should you do
measure acth
if high - acth dependent
what is a feature of non functioning pituitary adenoma
bitemporal hemianopia
can cause hypopituitarism
sometimes high prolactin
trans sphenoidal surgery needed
