Flashcards in Cushings Syndrome Deck (18)
What is cushings syndrome?
General term referring to a chronic excess and inappropriate levels of circulating CORTISOL whatever the cause
What is cushings disease?
Specifically relates to excess glucocorticoids resulting from inappropriate ACTH secretion from a pituitary tumour
Where is cortisol released from?
The sona fasciculate of the adrenal cortex
What are the 5 main functions of cortisol?
- Anti inflammatory
How is cortisol anti inflammatory?
It inhibits production of inflammatory mediators e.g prostaglandins and interleukins
How does cortisol cause vasoconstriction?
It increases the sensitivity of peripheral blood vessels to catecholamines
What is CRH?
Corticotropin releasing hormone
What is CRH and therefore cortisol released according to?
The cardiac rhythm and in stress
What is the most common cause of cushings syndrome?
Why do oral steroids cause cushings syndrome?
It mimics the action of cortisol and so causes a negative feedback and inhibits CRH release and therefore cortisol release
What is a spontaneous endogenous cause of cushings disease?
Pituitary adenoma (cushings disease)
What is the presentation of cushings syndrome?
- Obesity (trunk, abdomen and neck)
- Moon face
- Mood change
- Proximal weakness
- Gonadal dysfunction
- Protein catabolism - therefore muscle atrophy and thin skin that bruises easily
- Increased BP
What investigations would you do in cushings syndrome and cushings disease as an initial screening process?
- Careful drug history
- Random plasma cortisol
What is the 1st line test?
Overnight dexamethasone suppression test:
- Oral dexamethasone 1mg at 00:00
- Measure serum cortisol at 8AM
- Normally there will be cortisol suppression < 50nmol/L
- In Cushing’s syndrome there will be no suppression
What second line test if then performed if there is no suppression in the first line test?
Perform 48hr dexamethasone suppression test:
- Oral dexamethasone x4 a day for 2 days
- Measure cortisol at 0hrs and 48hrs
- In Cushing’s there will be no suppression of cortisol
What is the assumption is ACTH is undetectable?
An adrenal tumour is likely
If ACTH is detectable what is the assumption?