Pituitary conditions Flashcards
(30 cards)
What size is a microadenoma?
1cm or less
What size is a macroadenoma?
More than 1cm
What cranial nerves are most likely to be damaged by a pituitary adenoma?
Cranial nerves 3, 4 and 6
Name three dopamine antagonists
Bromocriptine (3xdaily)
Quinagolide (1xdaily)
Carbergoline (2xweek)
How do you treat a prolactinoma?
Dopamine antagonists
What is the diagnostic test for acromegaly?
Glucose tolerance test. Give 75g oral glucose and measure every 30 mins
What is the result of a GTT in someone with acromegaly as opposed to a normal person?
Normal: Suppress to below 0.4ug after glucose. No suppression in acromegaly
How do you treat acromegaly?
Surgery
If you have performed surgery for acromegaly but there is still a positive result on the GTT what do you do?
Drug therapy
- Dopamine agonist
- Octreotide
- Pegvisomant
What drugs treatment might you use pre operatively to shrink an adenoma and to relieve headache in acromegaly?
Somatostatin analogues
What are the two most likely long term side effects of somatostatin analogues?
Gastritis
Gallstones
Name three somatostatin analogues used in acromegaly
- Octreotide SC injection 3xdaily
- Sandostatin IM injection 1x every 28 days
- Lanreotide autogel IM injection 1x every 28 days.
How does pegvisomant work?
Binds to GH receptor and blocks its activity
What other type of drug is useful in acromegaly?
Dopamine agonist eg cabergoline
Name two screening tests used in cushings
Overnight 1mg dexamethasone supression test
24 hrs urine collections for cortisol measurement
Describe the overnight dexamethasone suppression test
1mg dexamethasone given at night.
Normal result: Cortisol will be below 50 the next morning
Abnormal result: More than 100
What do you calculate in the 24hr urine collection for cushings?
Cortisol creatinine ratio
What is a normal urinary free cortisol?
Less than 250
What is a normal cortisol creatinine ratio?
Less than 25
What is the definitive test for cushings?
Low dose dexamethasone test
Describe the low dose dexamethasone test?
2mg dexamethonse given each day for 2 days in small doses.
If the cortisol is less than 50 16 hrs after the last dose then there is no cushings.
Is cushings is it more commonly a pituitary problem or an adrenal problem?
Pituitary
What three tissues may produce ectopic ACTH?
Thymus
Lung
Pancreas
What is the treatment for pituitary cushings?
Surgery and external radiotherapy if there is a recurrence