Pituitary

Question 1

What are the 6 hormones produced by the anterior pituitary?

Answer 1

GH 
Prolactin 
TSH 
LH, FSH
ACTH

Question 2

What hormone stimulates GH production?

Answer 2

GHRH

Question 3

What hormone stimulates /suppresses prolactin?

Answer 3

TRH stimulates

dopamine suppresses

Question 4

What hormone stimulates LH, FSH

Answer 4

LHRH

Question 5

What hormone stimulates ACTH?

Answer 5

CRH

Question 6

Why do people with hypothyroidism commonly have hyperprolactinaemia?

Answer 6

Low T4 > positive feedback onto TRH > high TRH

TRH also stimulates prolactin

Question 7

What are symptoms of hyperprolactinaemia?

Answer 7

galactorrhea

amenorrhoea

Question 8

What types of prolactinoma can you get in terms of size?

Answer 8

micro adenoma = <1cm

macro adenoma = >1cm

Question 9

What visual field defect is caused by a prolactinoma?

Answer 9

Bilateral hemianopia

Due to compression of optic chiasm

Question 10

What visual testing is done for bilateral hemianopia?

Answer 10

Humphreys test

Question 11

When is a prolactinoma considered inoperable?

Answer 11

when it is in very close contact with the carotid arteries

Question 12

Define prolactinoma

Answer 12

An adenoma of the pituitary producing excess prolactin

Question 13

What prolactin results do you get with a prolactinoma?

Answer 13

x10 higher than upper limit for prolactin

so 6000

Question 14

What testing is important if a prolactinoma is suspected

Answer 14

Testing pituitary to see if it responds to metabolic stress by producing ACTH, GH

so perform a COMBINED PITUITARY FUNCTION TEST -

Question 15

What does a CPFT involve?

Answer 15

Give 3 stimuli:

• hypoglycaemia
• TRH
• LHRH

Question 16

What must you be aware of before performing a CPFT ‘

Answer 16

That hypoglycaemia is DANGEROUS

Therefore ensure that there are no cardiac RF (ECG normal) and no history of epilepsy

Question 17

What occurs to the patient when blood glucose drops below 1.5 mol/L

Answer 17

Neuroglycopoenia - patient loses consciousnes, becomes confused or aggressive

Question 18

How do you rescue a patient with severe hypoglycaemia?

Answer 18

50mL 20% dextrose IV

Question 19

What is the dose of insulin you must give in CPFT?

Answer 19

0.15 units/kg

Question 20

What hormone must be replaced urgently if ALL pituitary hormones are reduced?

Answer 20

HYDROCORTISONE

To replace cortisol

Question 21

What cortisol levels need to be reached for a CPFT to be normal?

Answer 21

Cortisol >550

Question 22

What GH levels need to be reached for a CPFT to be normal?

Answer 22

GH >10

Question 23

What hormones need to be given if pituitary function is suppressed?

Answer 23

hydrocortisone
Thyroxine
Oestrogen
GH

Question 24

What is front line treatment for a prolactinoma?

Answer 24

A dopamine agonist (bromocriptine/cabergoline)

This willl shrink the size of the tumour

Question 25

Other than a prolactinoma, what other tumour can cause increased prolactin?

Answer 25

a LARGE NON FUNCTIONING tumour

Question 26

How does a large non functioning tumour cause hyperprolactinaemia?

Answer 26

It compresses the pituitary stalk | Thereby prevents dopamine from reaching the pituitary

Question 27

How do you treat a large non functioning tumour?

Answer 27

SURGERY | They will NOT respond to dopamine agonist

Question 28

How do you distinguish a prolactinoma from a non functioning tumour?

Answer 28

SIZE & PROLACTIN RATIO A LARGE non functioning tumour (size detected by bitemporal hemianopia) will cause moderate increase in prolactin (around 3000) A SMALL prolactinoma can cause MASSIVE increase in prolactin

Question 29

What steroids can be given in ACTH / cortisol replacement=

Answer 29

Hydrocortisone - current front line Predisolone - potent steroid, longer half life, currently being trialled

Question 30

How do you test acromegalY?

Answer 30

Oral glucose tolerance test (as glucose suppresses GH) | IGF-1 levels

Question 31

How do you test GH deficiency in children?

Answer 31

Random plasma GH Exercise then test GH (exercise causes GH release) Do NOT do a GH stimulation test right away After these you can try INSULIN TOLERANCE TEST

Question 32

How do you treat acromegaly?

Answer 32

Octreotide (suppresses GH) Cabergoline (if tumour is co-secreting prolactin) Pituitary surgery Pituitary radiotherapy