Cushing's Syndrome Flashcards
which is the most common cause of cushings; exogenous or endogenous?
exogenous (e.g. glucocorticoid therapy)
what is cushing’s disease?
pituitary tumour secreting ACTH –> adrenal hyperplasia
name the ACTH dependent causes of cushing’s syndrome
- cushing’s disease (80%)
- ectopic ACTH production (20%)
what is ectopic ACTH production?
cause of cushing’s syndrome where ACTH is produced by malignancy
e.g. small cell lung cancer
name the ACTH independent causes of cushing’s syndrome
- iatrogenic: steroids
- adrenal adenoma
- andrenal carcinoma (rare)
- carney complex
- micronodular adrenal dysplasia (very rare)
what is carney complex?
cushing’s syndrome + cardiac myxoma
what is pseudo-cushing’s?
- mimics cushing’s
- causes false positive dexamethasone suppression test or 24 hr urinary free cortisol
what causes pseudo-cushings?
- alcohol excess
- severe depression
how can you tell between pseudo-cushings and cushing’s syndrome?
insuline stress test
what are the classical features of cushing’s syndrome?
- central adiposity
- stretch marks
- bruising
- hirsutism
- acne
what metabolic imbalance is seen in cushing’s syndrome?
hypokaelamic metabolic alkalosis
what electrolyte abnormality is seen in ectopic ACTH secretion?
very low potassium levels
what tests are used to confirm cushing’s syndrome?
- overnight dexamethasone suppression test
- 24 hr urinary free cortisol
what is the 1st line test for cushing’s syndrome?
overnight dexamethasone suppression
what does the overnight dexamethasone suppression test demonstrate in cushing’s syndrome?
morning cortisol spike is not suppressed
