when does Cushing’s syndrome occur
- occurs due to long term cortisol overexposure –> hypercortisolism
- (pathological overproduction of cortisol)
give some causes of Cushing’s syndrome
exogenous:
- iatrogenic (glucocorticoid prescription)
endogenous - ACTH dependent:
- ant. pit. tumour
- ectopic tumour
endogenous - ACTH independent: CARS
C - cancer (adrenal/hypothalamic adenoma)
A - adrenal nodular hyperplasia
R - rare causes e.g. McCune-Albright syndrome
S - steroid use
describe 1° hypersecretion due to adrenal problem
- ↓CRH
- ↓ACTH
- ↑cortisol
describe 2° hypersecretion due to pituitary problem
- ↓CRH
- ↑ACTH
- ↑cortisol
describe 2° hypersecretion due to hypothalamic problem
- ↑CRH
- ↑ACTH
- ↑cortisol
when does Cushing’s disease occur
overproduction of ACTH from ant. pit. adenoma
what is the most common cause of Cushing’s
anterior pituitary adenoma (60-70% of cases)
how might a Px w/ Cushing’s syndrome present
- central obesity (deposition of fat in face and abdomen)
- thin limbs (proximal limb muscle wasting)
- moon face
- hypertension
- buffalo hump
- abdominal striae
- hyperglycaemia
- pink in face
- insomnia, depression
- thinning of skin, easy bruising
- acne (comedones)
what causes hypertension in Cushing’s syndrome
cortisol binds to aldosterone receptors causing ↑ in BP
what causes acne in Cushing’s
↑androgens
describe the effects of hypercortisolism on carb metabolism
hyperglycaemia –> ‘adrenal diabetes’
describe the effects of hypercortisolism on prot metabolism
- protein shortage –> muscle weakness
- striae
- easy bruising and thinning of skin
what are some complications of Cushing’s
- osteoporosis
- immunosuppression
- diabetes mellitus
- delayed healing of fracture/soft tissue injuries
what test can be done to confirm ant. pit. adenoma in Cushing’s
dexamethasone suppression test
- measures cortisol and ACTH
- dexamethasone normally suppresses cortisol but not in Cushing’s disease
what other investigation can be done to confirm Cushing’s
free urinary cortisol
outline the management options for Cushing’s syndrome
treat underlying cause:
- trans-sphenoidal surgical removal of pituitary adenoma
- surgical removal of adrenal tumour
(mifepristone - a streoidogenesis inhibitor - can be use pre-operatively/if Px doesn’t want surgery, though much less effective)
