Pituitary Tumours Flashcards
What are the anterior pituitary cells and their hormones?
Corticotrophs- ACTH/ Corticotrophin
Gonadotrophs- FSH/LH (gonadotrophin)
Lactotrophs- Prolactin
Somatotrophs- Growth hormone/ somatotrophin
Thyrotrophs- TSH/ thyrotrophin
Functioning pituitary tumor types?
Somatotrophs- Acromegaly
Gonadotrophs- Gonadotrophinoma
Lactotrophs- Prolactinoma
Thyrotrophs- TSHoma
Corticotrophs- Cushing’s disease (corticotrophin adenoma
what is the most common functioning pituitary tumour
prolactinoma
what is a micro vs macroadenoma
micro - <1cm
macro - >1cm
HOW DOWE classify of pituitary tumours?
Radiological (MRI)
size- microadenoma vs macroadenoma
sellar/suprasellar
compressing optic chiasm or not
invading cavernous sinus or not
benign or malignant-pituitary carcinomas are very rare (<0.5% of pituitary tumours)
Mitotic index measured using Ki67 index – benign is <3%
Pituitary adenomas can have benign histology but display malignant behaviour)
functioning or non-functioning
Excess secretion of a specific pituitary hormone
eg prolactinoma
No excess secretion of pituitary hormone (Non Functioning Adenoma)
how do prolactinomas affect fertility?
prolactin binds to prolactin receptors on kisspeptin neurones in hypothalamus
inhibits kisspeptin release
decreases downstream GnRH/LH/FSH/Oest/Test
Causes oligoamenorrhoea/low libido/erectile dysfunction/ reduced pubic hair/ osteoporosis/infertility
how do prolactinomas present?
menstrual disturbance
erectile dysfunction
reduced libido
reduced pubichair
galactorrhoea (less common in men)
sub-fertility
what is normal serum [prolactin] and what is it in prolactinoma
men usually 300
women usually 550
> 5000mU/L
what may be physiological causes of falsely elevated prolactin?
pregnancy/breastfeeding
stress: exercise, seizure, venepuncture
nipple/chest wall stimulation
what may be some pathological causes for elevated prolactin besides prolactinoma?
primary hypothyroidism
polycystic ovarian syndrome
chronic renal failure (excretion issue)
what may be some iactrogenic causes of elevated prolactin besides prolactinoma
antipsychotics
SSRIs
anti-emetics
high dose oestrogen
opiates
what must you think of if you see mild serum prolactin elevation with no clinical features?
review the patients’ medication list
consider the stress of venepuncture
consider macroprolactin - sticky prolactin
what is macroprolactin?
polymeric form of prolactin - antibody-antigen complex of monomeric prolactin and IgG (natural variation in some people)
how do you resolve the stress of venepuncture?
measure sequential serum prolactin 20 mins apart with an indwelling cannula to reduce venepuncture stress
Investigation for prolactinomas
Once you have confirmed a true pathological elevation of serum prolactin, should you organise a pituitary MRI
how do you treat prolactinomas?
What does dose depend on?
What is the aim of treatment?
first line: medical
dopamine receptor agonists form mainstay of treatment e.g. Cabergoline (bromocriptine)
Safe in pregnancy
dose depends upon size of tumour
Aim is to normalise serum prolactin & shrink prolactinoma
How do dopamine receptor agonists reduce prolactin and shrink prolactinomas?
Prolactin secreting anterior pituitary lactotrophs have D2 receptors.
Dopamine binding D2 receptors inhibits prolactin secretion
Dopamine receptor agonists mimic dopamine andproduce this same effect
what is acromegaly?
excess growth hormone
How does excess growth hormone present in childrenvs adults
Children- gigantism
Acromegaly- adults
Acromegaly onset
Often insidious presentation – mean time to diagnosis from onset of symptoms = 10y
what are the symptoms of acromegaly?
sweatiness
headaches
coarsening of facial features- macroglossia, prominent nose, prognathism
snoring and obstructive sleep apnoea
increased hand&feet size
hypertension
impaired glucose tolerance/diabetes mellitus
Mechanisms of growth hormone action
how do you diagnose acromegaly?
GH pulsatile – so random measurement unhelpful
Elevated serum IGF-1
Failed suppression (‘paradoxical rise’) of GH following oral glucose load – oral glucose tolerance test
Prolactin can be raised – co-secretion of GH & prolactin
Once confirm GH excess, pituitary MRI to visualise pituitary tumour
What group of diseases does GH excess increase the risk of
Cardiovascular
treatment for acromegaly?
Aim of treatment?
First-line treatment is surgical – trans-sphenoidal pituitary surgery
Can use medical treatment prior to surgery to shrink tumour or if surgical resection incomplete
Somatostatin analogues eg octreotide – ‘endocrine cyanide’
Dopamine agonists eg cabergoline (GH secreting pituitary tumours frequently express D2 receptors)
Radiotherapy (slow, not specific for GH)
Aim to normalise serum GH and IGF-1
what is cushing’s syndrome?
excess of cortisol or other glucocorticoid
what are the symptoms of cushing’s syndrome
depression
red cheeks
fat pads
moon face
thin skin easy bruising, poor wound healing, purple striae and pendulous abdomen
Proximal myopathy
Osteoporosis
impaired glucose tolerance
hypertension
what are the ACTH dependent causes of cushings syndrome?
cushings disease - corticotroph adenoma (pituitary)
ectopic ACTH lung cancer
what are the ACTH independent causes of cushings syndrome?
steroids by mouth (common)
adrenal adenoma/carcinoma
diagnosis of cushings syndrome
24hr urine free cortisol showing increased cortisol secretion
should show elevated late night cortisol (loss of diurnal variation)
failed sppression on oral dexamethasone suppression test (exogenous glucocorticoid)
should show elevated cortisol
once hypercortisolism confirmed, measure ACTH
If ACTH high, piuitary MRI
what are non-functional pituitary adenomas?
tumours don’t secrete specific hormones
how do non-functional pituitary adenomas present?
visual disturbances (bitemporal hemianopias)
hypopituitarism
sometimes elevated prolactin (dopamine can’t travel down pit. stalk)
