1b Pituitary Tumours

Question 1

What is a functioning tumour of the somatotrophs called?

Answer 1

Acromegaly

Question 2

What is a functioning tumour of the lactotrophs called?

Answer 2

prolactinoma

Question 3

What is a functioning tumour of the Corticotrophs called?

Answer 3

Cushings Disease

Question 4

What is the name for a radiologically small and large pituitary tumour?

Answer 4

Microadenoma (<1cm) and macroadenoma (>1cm)

Question 5

What things are we looking for in an MRI?

Answer 5

Seller or suprasellar
Compressing optic chiasm or not
Invading carvenous sinus or not

Question 6

What are the two functional classifications for tumours?

Answer 6

excess hormone secretion or not (non-functioning adenoma)

Question 7

Are pituitary tumours generally malignant?

Answer 7

No (<0.5%)

Question 8

How do you tell the difference between malignant or benign tumour?

Answer 8

Mitotic index measured using Ki67 index - benign is <3%

Pituitary adenomas can have benign histology but display malignant behaviour

Question 9

Describe how hyperprolactinaemia leads to the associated symptoms?

Answer 9

Prolactin binds to prolactin
receptors on kisspeptin
neurons in hypothalamus

Inhibits kisspeptin release.

Decreases in downstream
GnRH/LH/FSH/T/Oest
Oligo-amenorrhoea/Low
libido/Infertility/Osteoporosis

Question 10

What is serum prolactin proportional to in prolactinomas?

Answer 10

The size of the tumour

Question 11

What is the hormonal presentation of prolactinomas?

Answer 11

low GnRH, low FSH and low LH
Usually serum concentration of prolactin >5000mU/L

Question 12

What are the clinical symptoms of prolactinoma?

Answer 12

Menstrual disturbance
Erectile dysfunction
Reduced libido
Galactorrhoea
Subfertility

Question 13

What are other causes of elevated prolactin?

Answer 13

Physiological
Pregnancy, stress, nipple stimulation

Pathological
Hypothyroidism, pcos or renal failure

Iatrogenic
Antipsychotics, oestrogen, opiates

Question 14

Why is prolactin levels higher in pregnancy?

Answer 14

Lactotrophs undergo hypertrophy

Question 15

Why does primary hypothyroidism cause elevated prolactin?

Answer 15

thyroid gland not working, therefore not producing thyroxine, so TSH rises which stimulates prolactin release

Question 16

How should a prolactinoma be investigated?

Answer 16

MRI - look for pituitary tumour

Question 17

What is the first line treatment of prolactinoma?

Answer 17

Cabergoline - dopamine receptor agonist

Question 18

How do dopamine receptor agonists reduce prolactin and shrink prolactinomas?

Answer 18

Dopamine is the off switch for prolactin, therefore dopamine binds to the D2 receptors on the lactotrophs and reduces prolactin production - can also used dopamine agonists like Cabergoline

Question 19

Where does the dopamine come from?

Answer 19

The dopaminergic neurones

Question 20

What is the difference between acromegaly and giganticism?

Answer 20

acromegaly is in adults, gigantism in children

Question 21

What is the problem with insidious prsentation of acromegaly?

Answer 21

long time between symptoms appearing and mean time to diagnosis

Question 22

What are some clinical symptoms of acromegaly?

Answer 22

Sweatiness
* Headache
* Coarsening of facial features
* Macroglossia
* Prominent nose
* Large jaw - prognathism
* Increased hand and feet size
* Snoring & obstructive sleep
apnoea
* Hypertension
* Impaired glucose
tolerance/diabetes mellitus

Question 23

What are the two mechanisms of growth hormone action?

Answer 23

direct and indirect

Direct = growth hormones acting on tissues
Indirect = GH act on liver, which makes IGF-1 which then acts on other body tissues

Question 24

How do you diagnose acromegaly?

Answer 24

GH pulsatile so random measurement is unhelpful

Failed suppression (‘paradoxical
rise’) of GH following oral
glucose load – oral glucose
tolerance test

Elevated IGF-1

Question 25

Why is it important that acromegaly must be treated?

Answer 25

Increased cardiovascular risk in untreated
acromegaly

Question 26

What is the first line treatment of acromegaly?

Answer 26

First-line treatment is surgical – trans-sphenoidal
pituitary surgery

Question 27

what is the medical treatment to do before surgery for treating acromegaly?

Answer 27

Somatostatin analogues eg octreotide –
‘endocrine cyanide’

Dopamine agonists eg cabergoline (GH
secreting pituitary tumours frequently express
D2 receptors)

Radiotherapy

Question 28

What are the clinical features of Cushings?

Answer 28

• Red Striae
• Buffalo humps - fat pads
• Lemon on sticks - centripedal obesity
• Moon face
• Proximal Myopathy - cannot get up from squat
• Easily bruising

Question 29

What us Cushings Syndrome?

Answer 29

Too much cortisol

Question 30

What is cushings Disease?

Answer 30

pituitary dependant adenoma

Question 31

What are ACTH dependant causes of hypercortisolism?

Answer 31

ACTH dependent
* Cushing’s disease (corticotroph
adenoma)
* Ectopic ACTH (lung cancer)

Question 32

What are ACTH indepedant causes of hypercortisolism?

Answer 32

ACTH dependent
* Taking steroids by mouth
(common)
* Adrenal adenoma or carcinoma

Question 33

What would you see in an investigation of Cushings?

Answer 33

1. Elevation of 24h free urine cortisol
2. Elevation of late night cortisol
3. Failure to suppress cortisol after oral dexamethasone so increased cortisol secretion

Question 34

What do you do when hypercortisolism is confirmed?

Answer 34

Measure ACTH - if high then pituitary MRI, CTH dependant

Question 35

What are the main effects of non-functioning pituitary adenomas

Answer 35

visual disturbances - bitemporal hemianopia

Question 36

What are the hormonal affects of non-functioning pituitary adenomas?

Answer 36

Can present with hypopituitarism
* Serum prolactin can be raised
(dopamine can’t travel down
pituitary stalk from hypothalamus)