Pituitary Flashcards
List the 6 anterior pituitary pituitary hormones
- LH
- FSH
- GH
- Prolactin
- TSH
- ACTH
What inhibits prolactin being released from the anterior pituitary?
Dopamine suppresses the release of prolactin
TRH also stimulates the release of prolactin, as well as TSH from the anterior pituitary
What is one of the major complications of a pituitary macroadenoma that should be examined for?
a macroadenoma may press on the optic chiasm causing a bitemporal hemianopia
What are the signs of a prolactinoma?
- Oligomennorrhea/amenorrhoea
- Galatactorrhoea
- Painful intercourse due to vaginal dryness
- Hirtusim/acne
A 30 year old presents with amenorrhoea and galactorrhoea. a CT scan of her pituitary shows a large macroadenoma
Her prolactin levels comes back st 30,000 (normal <600). She has not had sexual intercourse
What is the possible diagnosis?
A.Cushing’s disease
B.Acromegaly
C.Prolactinoma
D.Non-functioning pituitary adenoma
E.Conn’s syndrome
C. Prolactinoma
It is always a prolactinoma if prolactin >600
What is the aim of pituitary function testing?
To try to increase the levels of anterior pituitary hormones
What is a form of metabolic stress to the body that can form part of pituitary function tests? What being released from the pituitary will be affected?
Hypoglycemia = metabolic stress
Increase cortisol releasing factor from hypothalamus –> and this increase ACTH release from the anterior pituitary
Increases Growth hormone releasing factor from the hypothalamus –> and thus increased release of GH from the anterior pitutary
Describe CPFT=Triple test
•Complete pituitary function tests:
Hypoglycaemia causes metabolic stress hence:
- Increases CRF and thus ACTH
- Increases GHRH and thus GH
- TRH stimulates TSH and prolactin
- LHRH stimulates LH and FSH
What needs to be managed when performing complete pituitary function tests (CPFT)?
- Check blood glucose regularly
- Need to have adequate hypoglycemia (<2.2mM)
- If severe hypoglycaemia occurs/unconsciousness - the patient needs rescuing with 50ml of 20% dextrose
During CPFT how should someone in severe hypoglycaemia be resuced?
Rescue patient with 50ml of 20% dextrose
What is the method for complete pituitary function testing?
- Fast patient overnight
- ensure good IV access
- Weigh patient and calculate dose of insulin required (0.15 units /kg)
- 70 kg woman will need 10.5 units
- Mix the following in 5 ml syringe:
- Insulin 0.15 units / kg
- TRH 200 mcg
- LHRH 100 mcg
- Give Intravenously - patient will have a warm flush and may vomit
- Take blood for GLUCOSE, cortisol, GH, LH, FSH, TSH, and prolactin every 30 minutes up to 60 minutes plus basal thyroxine
- Check GLUCOSE, cortisol and GH up to 120 minutes
- What is the normal response to CPFT?
- What is the response if there is tumor pressing on the pituitary?
1.
- Glucose <2.2mM
- Cortisol reaches 550nM
- GH reaches 10 IU/l
- All cells may fail
- What are the abnormalities here?
- What urgently needs replacing?
- What drugs are also needed?
- Glucose is not reduced, GH, Cortisol, LH, FSH and TSH are all reduced. Prolactin is extremely high
- Urgent replacement needed: hydrocortisone and thyroxine
- Other treatments needed:
- Hydrocortisone replacement
- Thyroxine replacement
- Oestrogen replacement
- GH replacement
- Dopamine agonist - bromocriptine or cabergoline - treat prolactinoma
a) What is the cause of this woman’s abnormalities? (prolactin 2700) MRI shows a macroadenoma
- Cushing’s disease
- Acromegaly
- Prolactinoma
- Non-functioning pituitary adenoma
- Conn’s syndrome
b) Why do these abnormalities occur in this condition?
c) what urgent treatment is needed?
A) 4. Non-functioning pituitary adenoma
B) Prolactin is NOT that high
- Non-functioning adenoma presses on the stalk and cause pituitary failure
- Prevent dopamine reaching the pituitary
- Thus cause hyperprolactinaemia.
C) Urgent replacement: hydrocortisone
**Prednisolone can mimic the effect of hydrocortisone therapy, and may potentially have a longer half life and more affiinty for cortisol receptors
- What are the abnormalities here?
- What is the likely diagnosis?
A.Cushing’s disease
B.Acromegaly
C.Prolactinoma
D.Non-functioning pituitary adenoma
E.Conn’s syndrome
- What dynamic test is needed to confirm the diagnosis?
A.Low dose dexamethasone suppression test
B.High dose dexamethasone suppression test
C.Synacthen test
D.Glucose tolerance test
E.TRH stimulation test
- GH is extremely high
- B. Acromegaly
- D. Glucose tolerance test
