W6 - Pituitary Flashcards
Pituitary failure causes hypotension - T or F?
false – although you don’t make any ACTH and no cortisol, you still have ALDOSTERONE
List the 6 anterior pituitary hormones
GH
ACTH
FSH
LH
TSH
prolactin
if a patient presents with galactorrhoea and amenorrhoea, if you have a pituitary tumour more than 1 cm, that’s a __________
MACROADENOMA
If a patient has a pituitary macroadenoma, what complication should you examine for?
Bitemporal hemianopia
What is the pathophysiology of bitemporal hemianopia in macroadenoma?
When there is a pituitary macroadenoma, the growth presses on the CROSSING OVER FIBRES at the optic chiasm, hence why the outer vision is lost bilaterally.
30 year old galactorrhoea - A CT scan of her pituitary shows a large (2cm) macroadenoma.
Her prolactin level comes back at 30,000 (normal <600). She has not had sexual intercourse.
A) Cushing’s disease
B) Acromegaly
C) Prolactinoma
D) Non-functioning pituitary adenoma
E) Conn’s syndrome
C) Prolactinoma
A macroadenoma is always a prolactinoma is prolactin level is ______
>6000
What test do you order if you think there is pituitary failure? Describe the test
Combined pituitary function test (CPFT) aka the triple test
simultaneously inject 3 things:
- Insulin
- TRH
- GnRH (LHRH)
- TRH simulates TSH and prolactin
- LHRH stimulates LH and FSH
- hypoglycaemia:
*increases CRH => increases ACTH
*increases GHRH => increases GH
What do you check for in patient prior to a CPFT?
Ensure no
- cardiac risk factors
- angina
- ECG abnormalities
- history of epilepsy
Explain method for carrying out CPFT?
- Fast patient overnight
- Ensure good IV access + no risk factors
- Weight pt + calculate dose of insulin (0.15 U/kg)
- Administer IV triple drug (5ml syringe with insulin + TRH 200 mcg, LHRH 100 mcg)
- Take blood for glucose, cortisol, GH, LH/FSH, TSH, and prolactin every 30 mins + basal thyroxine up to 60 mins
- Continue glucose, GH, cortisol measuring for another 60 mins (2 hours total
How do your recover a patient at 1.5 mM glucose in a CPFT?
If severe hypoglycaemia occurs (or unconsciousness), rescue patient with 50 ml of 20% dextrose
=> pt will recover in 5 mins
Explain cut-offs and bodily physiological responses during a CPFT
- When glucose is about 3.0 mM, you get SNS activation = palpitations + sweat
- If patient’s pituitary is functioning, they will make cortisol and sugar will go back up
- Check blood glucose regularly => must reach adequate hypoglycaemia (<2.2mM)
* if by 30 mins you’re not at 2.2mM, give more insulin - If glucose very low (<1.5 mM), neuroglycopenia may occur = AGGRESSION
=> recover patient at 1.5mM
What is a normal response in CPFT?
Cortisol reaches 550 nM
GH reaches 10 IU/l
27 year old woman who also has a large 2cm pituitary adenoma with a visual field defect.
CPFT case:
30 min - glucose 1.8, GH 0.5, cortisol 170, LH 0.7, FSH 0.8, TSH 0.8, prolactin 2865
60 min - glucose 2.3, GH 0.5, cortisol 180, LH 0.9, FSH 1.3, TSH 0.9, prolactin 2766
90 min - glucose 4.7, GH 0.5, cortisol 160
What is the condition? What treatments (5) does she need?
non-functioning pituitary adenoma.
- HYDROCORTISONE replacement (MOST urgent)
- thyroxine replacement
- oestrogen replacement
- GH replacement ( if young and short)
- dopamine agonist (bromocriptine OR cabergoline) =>
Which hydrocortisone replacement is better - prednisolone or dexamethasone?
prednisolone
