[Endo] Cushing's syndrome Flashcards
what does Cushing’s syndrome cause?
hypercortisolism
what can the causes of Cushing’s syndrome be divided into?
- ACTH dependent
- ACTH independent
- exogenous
what does ACTH dependent mean?
increased/inappropriately normal ACTH
what are some ACTH dependent causes of Cushing’s syndrome?
- pituitary adenoma (Cushing’s disease)
- ectopic ACTH secretion
what does ACTH independent mean?
excessive cortisol despite suppressed ACTH
what are some ACTH independent causes of Cushing’s syndrome?
- adrenal adenoma
- bilateral adrenal hyperplasia
what are exogenous causes of Cushing’s syndrome?
exogenous corticosteroids use
what are the differentials for hypercortisolism?
- metabolic syndrome
- physical stress
- malnutrition
- alcoholism
- depression
- pregnancy
you suspect a pt has Cushing’s syndrome. what do you do first?
exclude exogenous glucocorticoid exposure
once you have excluded exogenous glucocorticoid exposure, what test would you perform?
one of:
- 24 h urinary cortisol
- overnight (low-dose) 1mg dexamethasone suppression test
- salivary cortisol
the test you performed for Cushing’s syndrome came back with an abnormal result. what do you do next?
- exclude physiological causes
- perform other tests that have not been initially completed. if abnormal result → Cushing’s syndrome diagnosed
you have confirmed a dx of Cushing’s syndrome. what test do you order now?
serum midnight ACTH measurement
serum midnight ACTH measurement showed an inappropriately normal/raised ACTH. what does this mean?
ACTH dependent cause
how do you further investigate an ACTH dependent cause of Cushing’s syndrome?
high-dose dexamethasone suppression test
high-dose dexamethasone suppression test shows cortisol being suppressed. what is the cause of Cushing’s syndrome?
Cushing’s disease (pituitary adenoma)
how do you confirm a dx of Cushing’s disease?
pituitary MRI
high-dose dexamethasone suppression test does not suppress cortisol. what is the cause of Cushing’s syndrome?
ectopic ACTH
how do you confirm a dx of Cushing’s syndrome 2˚ to ectopic ACTH?
CT TAP
serum midnight ACTH measurement showed a low ACTH. what does this mean?
ACTH independent cause
how do you further investigate an ACTH independent cause of Cushing’s syndrome?
CT TAP for ? adrenal adenoma
what may be needed to differentiate between pituitary and ectopic ACTH secretion?
petrosal sinus sampling of ACTH
what is the medical mx for Cushing’s disease?
one of:
- somatostatin analogues
- steroidogenesis inhibitors
- glucocorticoid receptor antagonists
what is the surgical mx for Cushing’s disease?
transsphenoidal resection of pituitary adenoma
what is the mx for ACTH independent Cushing’s syndrome?
surgical: laparoscopic adrenalectomy
what is the medical mx for ectopic ACTH?
one of:
- somatostatin analogues
- steroidogenesis inhibitors
- glucocorticoid receptor antagonists
what is the surgical mx for ectopic ACTH?
- surgical resection of the ACTH producing tumour
- bilateral adrenalectomy
young female with resistant HTN and hypokalaemia. dx?
Conn’s syndrome
headache, sweating, tachycardia and HTN. dx?
phaeochromocytoma
suppressed cortisol levels following high dose dexamethasone suppression. dx?
Cushing’s disease (pituitary adenoma)
why should you never suddenly stop / omit long-term steroids?
can precipitate Addisonian crisis
