Pituitary Tumours

Question 1

What are the anterior pituitary cells and their hormones?

Answer 1

Corticotrophs- ACTH/ Corticotrophin
Gonadotrophs- FSH/LH (gonadotrophin)
Lactotrophs- Prolactin
Somatotrophs- Growth hormone/ somatotrophin
Thyrotrophs- TSH/ thyrotrophin

Question 2

Functioning pituitary tumor types?

Answer 2

Somatotrophs- Acromegaly
Gonadotrophs- Gonadotrophinoma
Lactotrophs- Prolactinoma
Thyrotrophs- TSHoma
Corticotrophs- Cushing’s disease (corticotrophin adenoma

Question 3

what is the most common functioning pituitary tumour

Answer 3

prolactinoma

Question 4

what is a micro vs macroadenoma

Answer 4

micro - <1cm
macro - >1cm

Question 5

HOW DOWE classify of pituitary tumours?

Answer 5

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)

Question 6

how do prolactinomas affect fertility?

Answer 6

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

Question 7

how do prolactinomas present?

Answer 7

menstrual disturbance
erectile dysfunction
reduced libido
reduced pubichair
galactorrhoea (less common in men)
sub-fertility

Question 8

what is normal serum [prolactin] and what is it in prolactinoma

Answer 8

men usually 300
women usually 550

> 5000mU/L

Question 9

what may be physiological causes of falsely elevated prolactin?

Answer 9

pregnancy/breastfeeding
stress: exercise, seizure, venepuncture
nipple/chest wall stimulation

Question 10

what may be some pathological causes for elevated prolactin besides prolactinoma?

Answer 10

primary hypothyroidism
polycystic ovarian syndrome
chronic renal failure (excretion issue)

Question 11

what may be some iactrogenic causes of elevated prolactin besides prolactinoma

Answer 11

antipsychotics
SSRIs
anti-emetics
high dose oestrogen
opiates

Question 12

what must you think of if you see mild serum prolactin elevation with no clinical features?

Answer 12

review the patients’ medication list
consider the stress of venepuncture
consider macroprolactin - sticky prolactin

Question 13

what is macroprolactin?

Answer 13

polymeric form of prolactin - antibody-antigen complex of monomeric prolactin and IgG (natural variation in some people)

Question 14

how do you resolve the stress of venepuncture?

Answer 14

measure sequential serum prolactin 20 mins apart with an indwelling cannula to reduce venepuncture stress

Question 15

Investigation for prolactinomas

Answer 15

Once you have confirmed a true pathological elevation of serum prolactin, should you organise a pituitary MRI

Question 16

how do you treat prolactinomas?
What does dose depend on?
What is the aim of treatment?

Answer 16

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

Question 17

How do dopamine receptor agonists reduce prolactin and shrink prolactinomas?

Answer 17

Prolactin secreting anterior pituitary lactotrophs have D2 receptors.
Dopamine binding D2 receptors inhibits prolactin secretion
Dopamine receptor agonists mimic dopamine andproduce this same effect

Question 18

what is acromegaly?

Answer 18

excess growth hormone

Question 19

How does excess growth hormone present in childrenvs adults

Answer 19

Children- gigantism
Acromegaly- adults

Question 20

Acromegaly onset

Answer 20

Often insidious presentation – mean time to diagnosis from onset of symptoms = 10y

Question 21

what are the symptoms of acromegaly?

Answer 21

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

Question 22

Mechanisms of growth hormone action

Answer 22

Question 23

how do you diagnose acromegaly?

Answer 23

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

Question 24

What group of diseases does GH excess increase the risk of

Answer 24

Cardiovascular

Question 25

treatment for acromegaly?
Aim of treatment?

Answer 25

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

Question 26

what is cushing’s syndrome?

Answer 26

excess of cortisol or other glucocorticoid

Question 27

what are the symptoms of cushing’s syndrome

Answer 27

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

Question 28

what are the ACTH dependent causes of cushings syndrome?

Answer 28

cushings disease - corticotroph adenoma (pituitary)
ectopic ACTH lung cancer

Question 29

what are the ACTH independent causes of cushings syndrome?

Answer 29

steroids by mouth (common)
adrenal adenoma/carcinoma

Question 30

diagnosis of cushings syndrome

Answer 30

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

Question 31

what are non-functional pituitary adenomas?

Answer 31

tumours don’t secrete specific hormones

Question 32

how do non-functional pituitary adenomas present?

Answer 32

visual disturbances (bitemporal hemianopias)
hypopituitarism
sometimes elevated prolactin (dopamine can’t travel down pit. stalk)