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 Diseas

Question 4

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

Answer 4

Microadenoma and macroadenoma

Question 5

What are the two functional classifications for tumours?

Answer 5

excess hormone secretion or not (non-functioning adenoma

Question 6

Are pituitary tumours generally malignant?

Answer 6

No

Question 7

Describe how hyperprolactinaemia leads to the associated symptoms?

Answer 7

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 8

What is serum prolactin proportional to in prolactinomas?

Answer 8

The size of the tumour

Question 9

What is the hormonal presentation of prolactinomas?

Answer 9

low GnRH, low FSH and low LH

Question 10

What are the clinical symptoms of prolactinoma?

Answer 10

Menstrual disturbance
* Erectile dysfunction
* Reduced libido
* Galactorrhoea
* Subfertility

Question 11

What is Galactorrhoea?

Answer 11

Breasts producing milk outside pregnancy

Question 12

why is Galactorrhoea more common in women?

Answer 12

Need oeastrogen to prime the breats for lactation

Question 13

What are three physiological causes of elevated prolactin

Answer 13

• Pregnancy/breastfeeding
• Stress: exercise, seizure, venepuncture
• Nipple/chest wall stimulation

Question 14

Why is prolactin levels higher in pregnancy?

Answer 14

Lactotrophs undergo hypertrophy

Question 15

What are the pathological causes of elevated prolactin?

Answer 15

• Primary hypothyroidism
• Polycystic ovarian syndrome
• Chronic renal failure

Question 16

Why does primary hypothyroidism cause elevated prolactin?

Answer 16

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

Question 17

How should a prolactinoma be investigated?

Answer 17

MRI - look for pituitary tumour

Question 18

What is the first line treatment of prolactinoma?

Answer 18

Cabergoline - dopamine receptor agonist

Question 19

How do dopamine receptor agonists reduce prolactin and shrink prolactinomas?

Answer 19

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 20

Where does the dopamine come from?

Answer 20

The dopaminergic neurones

Question 21

What is the difference between acromegaly and giganticism?

Answer 21

acromegaly is in adults, gigantism in children

Question 22

What is the problem with insidious prsentation of acromegaly?

Answer 22

long time between symptoms appearing and mean time to diagnosis

Question 23

What are some clinical symptoms of acromegaly?

Answer 23

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 24

What are the two mechanisms of growth hormone action?

Answer 24

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 25

How do you diagnose acromegaly?

Answer 25

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

Question 26

Why are random measurements of growth hormone not useful?

Answer 26

GH is pulsatile so random measurements are unhelpful

Question 27

Why is it important that acromegaly must be treated?

Answer 27

Increased cardiovascular risk in untreated acromegaly

Question 28

What is the first line treatment of acromegaly?

Answer 28

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

Question 29

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

Answer 29

Somatostatin analogues eg octreotide – ‘endocrine cyanide’ Dopamine agonists eg cabergoline (GH secreting pituitary tumours frequently express D2 receptors)

Question 30

What are the clinical features of Cushings?

Answer 30

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

Question 31

What us Cushings Syndrome?

Answer 31

Too much cortisol

Question 32

What are the common causes of Cushings Syndrome?

Answer 32

Causes of Cushing’s syndrome * Taking steroids by mouth (common) * Pituitary dependent Cushing’s disease (pituitary adenoma) * Ectopic ACTH (lung cancer) * adrenal adenoma or carcinoma

Question 33

What is cushings Disease?

Answer 33

pituitary dependant adenoma

Question 34

What are ACTH dependant causes of Cushings?

Answer 34

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

Question 35

What are ACTH indepedant causes of Cushings?

Answer 35

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

Question 36

What would you see in an investigation of Cushings?

Answer 36

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 37

What do you do when hypercortisolism is confirmed?

Answer 37

Measure ACTH - if high then pituitary MRI, CTH dependant

Question 38

What are the main effects of non-functioning pituitary adenomas

Answer 38

visual disturbances - bitemporal hemianopia

Question 39

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

Answer 39

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