Cushing's disease Flashcards
what is cushings disease
chronic glucocorticoid (cortisol) excess
what is the most common cause of cushings disease
a pituitary adenoma causing increased ACTH production
give three ACTH dependent causes of cushings disease
bilateral adrenal hyperplasia from an ACTH secreting pituitary adenoma
ectopic acth production from SCLC + carcinoid tumours
ectopic CRF production resulting from some thyroid/medullary cancers
give some clinical features of cushings disease
increased weight mood change proximal weakness gonadal dysfunction acne recurrent achilles tendon rupture
give some things you might see on examination of a patient with cushings disease
central obesity moon face buffalo hump bruises purple abdominal striae osteoporosis skin and muscle atrophy hyperglycaemia high BP
what are the first line investigations for cushings disease
overnight dexamethasone suppression test
24h urinary free cortisol test
in cushings disease what would you expect to see on a 24h urinary free cortisol test
lots of cortisol!
what would you expect to see on an overnight dexamethasone suppression test
NO suppression of cortisol
if ACTH IS suppressed then it would be an ACTH independent cause
if plasma ACTH is undetectable what is the likely cause
adrenal tumour
how can you find the cause of cushings disease
plasma ACTH
CRH stimulation test
what would you expect to see on a CRH stimulation test
cortisol would rise if there is pituitary disease
cortisol would NOT rise in an ectopic ACTH/adrenal disease
describe the HPA axis
the hypothalamus produced corticotrophin releasing hormone (CRH)
the anterior pituitary produces ACTH
the adrenals produce cortisol
