Pituitary Flashcards
Does pituitary failure cause hypotension?
No.
What are 6 hormones released by the anterior pituitary gland?
- Growth hormone
- Thyroid Stimulating Hormone
- Prolactin
- LH
- FSH
- ACTH
What causes the release of these 6 hormones?
- GH = GHRH, inhibited by somatostatin
- TSH = TRH
- Prolactin = stimulated by TRH and inhibited by dopamine
- LH/FSH = GnRH
- ACTH = CRH
What are the symptoms of pituitary dysfunction? and which hormones cause this?
- Amernorrhea = lack of LH and FSH
- Galactorrhoea = excess prolactin
- Acromegalic symptoms = excess GH
- Bitemporal hemianopia = Macroadenoma
How can hypothyroidism cause galactorrhoea?
- Hypothyroidism causes an increase in TRH release.
- TRH is responsible for TSH release BUT also prolactin.
- Therefore prolactin levels increase and result in galactorrhea
How can non-functioning pituitary adenomas cause a hyperprolactinoma?
Prevents dopamine (which inhibits prolactin) reaching the pituitary because of compression of the pituitary stalk
How do you investigate the function of the pituitary gland? How do you carry out this test?
Combined Rapid Acting Anterior Pituitary Function Test
- > Fast patients overnight
- > Ensure good IV Access
give the following in a single 5ml syringe;
i) Insulin 0.15units/kg
ii) TRH 200mcg
iii) LHRH 100mcg
What is the idea behind the CPFT?
To stress the patient so that they release hormones from the pituitary gland.
You can then measure these hormones to assess function
What are warnings of the CPFT?
The test involves inducing Hypoglycaemia
- > Ensure no Cardiac Risk Factors
- > No angina Hx
- > Normal ECG
- > No History of Epilepsy
This is as the first response of Hypoglycaemia is Adrenaline release which can induce the risks above
Aiming for <2mM
What happens if the glucose of the patient is <1.5mM during the test?
Neuroglycopenic
In which case, give patient 50ml of 20% dextrose
How do you assess a CPFT?
- Measure glucose and hormones every 30 mins for 2 hours.
- Glucose should fall below 2.2 at 30 mins but recover after
- All other hormones should increase
Which hormone therapy is urgent for someone with a dysfunctional pituitary gland?
Hydrocortisone Repacement is URGENT
-> Deficiency can lead to Shock
What is the order of the hormones given as part of the therapy for a dysfunctional pituitary gland?
- > Hydrocortisone
- > Thyroxine
- > Oestrogen/Testosterone
- > Growth Hormone
How can you treat a prolactinoma? and what side effects can they cause?
Bromocriptine/Cabergoline i.e. Dopamine Agonists.
Dopamine Agonists may cause psychotic side effects.
How do you differentiate between a non functioning pituitary adenoma and a prolactinoma?
Prolactin < 6000 = non functioning pituitary adenoma or v small prolactinoma
Prolactin >6000 = prolactinoma
