Endocrinology - Cushing's syndrome Flashcards
1
Q
name the causes of Cushing’s syndrome
A
- use of glucocorticoids
- ACTH-secreting pituitary adenoma (Cushing’s disease)
- ectopic ACTH-producing tumours, e.g. small cell lung cancer
- adrenal adenoma or carcinoma (adrenal Cushing’s)
2
Q
describe the characteristic features of Cushing’s syndrome
A
- facial fullness (moon facies)
- weight gain, central obesity
- supraclavicular fat pads, buffalo hump
- proximal muscle weakness
- skin atrophy, purple striae, easy bruising
- hirsuitism
- acne
- psychological problems: depression, cognitive dysfunction and emotional lability
- gonadal dysfunction, decreased libido, irregular menses
3
Q
describe symptoms that can be caused specifically by Cushing’s diseases
A
- headaches
- visual disturbance
- galactorrhoea
4
Q
suggest conditions that can arise due to Cushing’s syndrome
A
- diabetes or impaired glucose tolerance
- HTN
- nephrolithiasis
- osteopenia or osteoporosis
- impaired immune function: increased infections, difficulty with wound healing
5
Q
which tests can be used to diagnose cushing’s syndrome?
A
- 24 hr urinary free cortisol (x3): 2+ collections measure cortisol excretion as >3x upper limit of normal
- low-dose dexamethasone suppression test:
- late night salivary cortisol
Bloods: raised WCC, hypokalaemia, metabolic alkalosis
6
Q
how would you ID cause of Cushing’s syndrome?
A
Exclude exogenous glucocorticoid use.
- Measure plasma ACTH
- low/undectable: Adrenal Cushing’s (ACTH-independent) likely - perform abdo CT or MRI to ID adrenal adenoma/carcinoma.
- high: ACTH-dependent Cushing’s syndrome - If high plasma ACTH, perform high-dose dexamethasone suppression test (8mg)
- if >50% suppression, indicates pituitary cause (Cushing’s disease) - perform pituitary MRI scan
- if no suppression, suggests ectopic ACTH production - perform chest CT scan (?lung cancer)
May measure plasma CRH also - ectopic CRH is very rare cause of Cushing’s syndrome.
