Pituitary Flashcards
T or F :
Pituitary failure causes hypotension
FALSE
In which endocrine organ failure is blood pressure low? Which hormone is low causing this?
Addison’s disease (adrenal)
Low Aldosterone (+ Cortisol)
Which hormones are low in pituitary failure?
Growth Hormone
Prolactin
TSH
LH
FSH
ACTH
Which hypothalamic hormone is inhibitory, and on the production of which anterior pituitary hormone?
Dopamine is inhibitory on the production of Prolactin
What does thyrotropin releasing hormone stimulate in the anterior pituitary?
TSH
Prolactin
In a patient presenting with galactorrhea/ amenorrhoea and a macroadenoma (>1cm) what complication should you examine for?
Bitemporal hemianopia
(Macroadenoma presses on optic chiasm)
30F
Galactorrhea
Amenhorroea
2cm macroadenoma on CT
Prolactin: 30,000
What is the diagnosis? What further investigation is necessary?
Prolactinoma
(normal <600)
Pituitary function testing
Why is pituitary function testing performed when a pituitary tumour is detected?
Tumour will press on other cells- potentially squeeze them out of existing
To ensure pituitary gland responds adequately to metabolic stress (ACTH + GH)
To ensure gonadotropins + thyrotrophs are functional
What are the elements of a combined pituitary function test? (CPFT)
LHRH to increase LH + FSH
TRH to increase TSH + prolactin
Stress to test ACTH + GH
What kind of stress is used in a CPFT?
Insulin induced hypoglycaemic stress
Increases CRH + thus ACTH
Increases GHRH + thus GH
What conditions must be checked for prior to a hypoglycaemic stress test?
Cardiac RFs/ Angina/ Abnormal ECG (may precipitate MI)
Epilepsy (may precipitate fit)
How may a patient react behaviourally to a hypoglycaemic stress test?
Low glucose: Sympathetic activation- sweaty, palpitations
V low glucose <1.5: Neuroglycopenia, aggression
What is considered adequate stress in hypoglycaemia in CPFT?
<2.2mM
What action must be taken if severe hypoglycaemia or unconsciousness occurs in a CPFT?
Rescue patient with 50ml of 20% Dextrose
Need good IV access prior as pt may become aggressive
Describe methodology of a CPFT
Fast patient overnight
Ensure good IV access
Weigh patient + calculate dose of insulin required: 0.15 units/ kg
Insulin + 200mcg TRH + 100mcg LHRH IV bolus
How frequently should measurements be recorded in a CPFT?
Glucose, Cortisol, GH, LH, FSH, TSH + Prolactin every 30m up to 60m
+ basal thyroxine
Glucose, Cortisol + GH up to 120m
Describe these results seen in a patient with a prolactinoma
Glucose drops- significant hypo
No GH produced
No rise in Cortisol
No rise in LH, FSH or TSH
Prolactin remains sky high
In a patient who has failed to respond to a CPFT, which treatment is needed urgently?
Hydrocortisone replacement
Thyroxine, GH, HRT but not urgent
(don’t need fludrocortisone, already have aldosterone as Adrenals healthy)
In addition to hormone replacement, what drug should be prescribed to a patient with a prolactinoma?
Cabergoline or Bromocriptine
Dopamine agonists to reduce prolactin
27F with a 2cm pituitary adenoma and bitemporal hemianopia
What occurs in the CPFT?
What is the diagnosis? Why is the prolactin high?
Glucose falls
GH remains the same
Non-functioning pituitary adenoma
Press on stalk causing pituitary failure
Prevent dopamine reaching lactotrophs causing secondary hyperprolactinaemia
What treatment is NOT needed in a 27F with a non functioning pituitary adenoma?
A. Fludrocortisone replacement
B. Hydrocortisone replacement
C. Thyroxine replacement
D. Oestrogen replacement
E. GH replacement
A. Fludrocortisone replacement
In a patient with a non functioning pituitary adenoma, what treatment may be offered on top of hormone replacement? Why?
Cabergoline if they want to get pregnant
28F with a 2cm pituitary adenoma and a bitemporal hemianopia.
Describe the abnormalities.
What is the diagnosis?
Glucose falls
GH increases
Baseline cortisol is low
Thyroxine is low because tumour has caused hypothyroidism
High prolactin suggests tumour
Pituitary gland failure except GH
Acromegaly
When suspecting acromegaly what dynamic test is needed?
A. Low dose dexamethasone suppression test
B. High dose dexamethasone suppression test
C. Synacthen test
D. Glucose tolerance test
E. TRH stimulation test
Glucose tolerance test
