pituitary tumours Flashcards
what are the types of cells in pituitary and hormones they release?
somatotrophs: GH, corticotrophs: ACTH (corticotrophin) , thyrotrophs (TSH) thyrotrophin, gonadotrophs LH FSH, lactotrophs: PROLACTIN
what happens when you have a functioining pituitary tumour arising from a somatotroph?
acromegaly
what happens when you have a pituitary tumour arising from a lactotroph?
prolactinoma
what happens when you have a pituitary tumour arising from a thyrotroph?
TSHoma
is a TSHoma common?
no
what happens when you have a pituitary tumour arising from a gonadotroph?
gonadotrophinoma
what happens when you have a pituitary tumour arising from a corticotroph?
cushings disease (corticotroph adenoma)
what are th etwo pit cell types for wchich a pit tumour leads to a NAMED disease and what are the diseases
corticotrophs: cushings, somatotrophs: acromegaly
what can you find out about pit tumours in MRI
when you want to find out 1) size and 2) location
classifications on size
microadenoma < 1cm
macro adenoma> 1cm
how common is it to have a microadenoma?
1/5 ppl have one
3 classifications/ standard considerations based on location
1) sellar (in sella turnica) and supprasellar (above sella turnica)
2) compressing optic chiasm or not
3) invading cavernous sinus or not
pit tumour classifications based on function
functional if they lead to increased pit hormone release, and non functioning adenoma if they dont
what is a malignant pituitary tumour called?
pituitary carcinoma
how common are pit carcinomas?
very rare <0.5% of pit tumours
what index is used to measur emitotic index and below what percentage is a tumour considered beingn?
ki67 index <3%
can benign pituitary adenomas invade nearby structures in the brain?
yes, because even though they have benign histology they can display malignant behaviour
what does the excess prolactin do in hyperprolactinaemia?
binds to prolactin receptors on kisspeptin neurons in hypothalamus inhibiting kisspeptin release
what chain of hormones is stimulated by kisspeptin?
kisspeptin stimulates GnRH release from hypothalamus, which stimulates LH and FSH release from gonadotrophs in anterior pituitary which stimulates oestrogen progesterone in reproductibe organs
what are the end symptoms of kisspeptin inhibition by prolactin?
oligomenorrhoea/ low libido (in both genders) / infertility / osteoporosis
what is the most common type of functional pit adenoma?
prolactinoma
what is the usual prolactin serum level in prolactinomas?
prolactin> 5000 mU/L
does an increase in size of the prolactinoma affect the prolactin serum levels?
yes they increase
presenting symptoms of prolactinomas:
only women:
1)mentrual disturbance
2)subfertility
3 related to sex and reproduciton:
erectile dysfunction
low libido
subfertility
do men or women more usually present with larger prolactinomas?
Men: big (bc no clear syptoms just low libido)
Women: usually smaller bc picked earlier bc you notice irregular periods also women try to have babies so
other physiological causes of elevated prolactin? (3 categories 5 specifics)
breastfeeding,
“stress” stimulus:
1)exercise
2)seizure
3) venepuncture
nipple/ chest wall stimulation
3 pathological causes of high prolactin other than prolactinoma
primary hypothyroidism
polycystic ovarian syndrome
chronic renal failure
what type of drugs usually cause high prolactin?
dopamine antagonists
what are 5 specific drugs that cause high prolactin? (iatrogenic causes of high prolact)
1) antipsychotics
2) selective serotonin re-uptake inhibitors
3) anti-emetics
4) high dose oestrogen
5) opiates
WHEN should you order a pituitary MRI for prolactinaemia?
only once you have confirmed PATHOLOGICAL elevation of serum prolactin
is the first line treatment of prolactinomas medical or surgical?
medical
what type of drug do you give as a first line treatment of prolactinomas?
dopamine receptor agonists
what is the currently commonly used dopamine receptor agonist?
cabergoline
which specific dopamine receptor does cabergoline attack?
D2 receptor
is cabergoline safe in pregnancy?
yes
what (2 things) do dopamine receptor agonists do?
1) reduce prolactin serum levels
2) shrink prolactinomas
what would you do differently in temrs of drug administration for micro and macroprolactinomas?
lesser and greater dose equivalently
how do dopamine receptor agonists work?
bind to D2 (dopamine) receptors on lactotrophs, immitating the effect of dopamine and blocking prolactin release
what is the consequence of excess GH in adults
acromegaly
what is the consequence of excess GH in children
gigantism
what is the meantime of diagnosis from onset of sympotms from acromegaly and why?
10 yrs bc it comes on gradually and ppl dont notice it
sympotms of acromegaly other than enlarged stuff
sweating
headache
hypertension
impaired glucose tolerance/ diabetes melitus
symptoms of acromegaly linjed to enlarged stuff
1)coarsening of facial features: macroglossia, prominent nose, large jaw: prognathnism
2)increased hand and feet size
3)snoring and obstructive sleep apnea (cartilage on throat enlarges)
what is the mechanism of GH action that leads to imparied glucose tolerance in acromegaly?
GH stimulates release of insulin like growth factor (somatomedin: a version of growth factor that is structurally a lot like insulin) from the liver
what system is at risk if acromegaly is left untreated?
cardiovascular
is the first line treatment of acromegaly surgical or medical and what is it spesifically?
surgical: transsphenoidal pit surgery (through nose)
what is the aim of surgical intervention for acromegaly?
lower GH and IGF-1 LEVELS
WHEN CAN YOU use medical treatment in treating acromegaly and with what purpose?
before surgery to shrink tumour or after surgery if surgical resection is incomplete
what drugs are used to treat acromegaly: types and 1 ex each
somatostatin analogues eg octreotide
dopamine agonists eg cabergoline
why do dopamine agonists work for acromegaly treatment?
bc GH pit tumours frequently exoress d2 receptors
what other mehtod of treatign other than surg and drugs and what is disadvanatge
radiotherapy
which biovhemical test confirms acromegaly?
rise in GH after glucose load
skin related symptoms in cushings syndrome
easy bruising
red cheecks
poor wound healing
thin skin: (easily pulled )
fat related symptoms in cushings syndrome
moon face
fat pads (buffalo bump - bit afto pou ehei i mama stin plati pano pano )
purple/ red striae (stretch marks)
pendulus abdomen (hanging over pubis)
other cushings syndrome symptoms
1) osteoporosis
2) proximal myopathy (you can also tell by thin arms and legs)
3) impaired glucose tolerance
4) high bp
5) mental changes
differencee between cushings disease and syndrome
disease: caused by pit adenoma, syndrome is just the symtpoms, may have any cause
what are the 3 investigations you carry out for cushings disease
1) test for free cortisol in urine -24h round bc of incr cortisol secretion
2) cortisol in blood or saliva at midnight
3) give oral dexamethasone (exogenous glucocorticoid) ull see failure to supress cortisol: incr cortisol secr
what causes of cushings SYNDROME are acth independent?
oral steroids (common)
adrenal adenoma or carcinoma
why do you need to measure cortisol at midnight? what does high at midninght mean ?
(bc cortisol is low at night, if its high midnight means loss of diurnal rhythm)
what causes of cushings SYNDROME are acth dependent?
cushings disease, (pituitary corticotroph adneoma)
ectopic acth: lung cancer
what do you do once you confirm hypercotisolism?
measure ACTH
when should you order a pituitary MRI (cushigs syndrome related)
when you find high acth after high cortisol
what do non functioning pit adenomas often present with?
visual disturbance (bitemporal hemianopia)
can a non funtioning pituitary adenoma affect pit hormones?
typically doesnt but it CAN cause
1)hypopituitarism or
2) raised serum prolactin
how do pituitary adenomas sometimes raise serum prolactin?
they squeeze the pituitary stalk and dopamine cant travel down from hypithalamus
what treatment is needed for pituitary adenomas?
trans-sphenoidal surgery for larger tumors epsecially if they are causing a visual disturbance
