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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?

- Protolysis
- Lipolysis
- Gluconeogenisis
- Anti inflammatory
- Vasoconstriction


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?

Oral steroids


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
- Acne
- Increased BP
- Infections
- Osteoporosis
- Hyperglycaemia


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?

Pituitary cause


What are the treatment options?

- Stop steroids
- If related to a tumour then surgical removal