Cushing's syndrome Flashcards
summarise a typical presentation of a patient with cushing’s syndrome?
- Increasing weight
- fatigue
- easy bruising
- thin skin
- poor wound healing
- moon face
- facial plethora
- interscapular fat pads
- proximal muscle weakness
- central obesity and pink/purple striae
define cushing’s syndrome?
syndrome associated with innapropriate elevation of free circulating cortisol
what are the risk factors for cushings?
exogenous corticosteroid use
pituitary adenoma
adrenal adenoma
adrenal carcinoma
explain the aetiology/ risk factors for cushing’s syndrome?
- It can be divided into ACTH Dependent (80%) and ACTH Independent (20%)
- ACTH Dependent
- Excess ACTH from a pituitary adenoma (Cushing’s disease)
- Ectopic ACTH (e.g. lung cancer, pulmonary carcinoid tumours)
• ACTH Independent
- Benign adrenal adenoma
- Adrenal carcinoma
• TAKING STEROIDS - would cause bilateral adrenal atrophy
summarise the epidemiology of cushing’s syndrome?
• Incidence: 2-4/1,000,000 per year
Peak incidence 20-40 yrs
what are the presenting symptoms of cushing’s
• Increasing weight • Fatigue • Muscle weakness • Myalgia • Thin skin • Easy bruising • Poor wound healing • Fractures • Hirsuitism • Acne • Frontal balding • Oligomenorrhoea/amenorrhoea Depression or psychosis
what are the signs of of cushing’s on physical examination?
• Moon face • Facial plethora • Interscapular fat pad • Proximal muscle weakness • Thin skin • Bruises • Central obesity • Pink/purple striae on abdomen/breast/thighs • Kyphosis (due to vertebral fracture) • Poorly healing wounds • Hirsuitism, acne, frontal balding • Hypertension • Ankle oedema (due to salt and water retention from the mineralocorticoid effect of excess cortisol) Pigmentation in ACTH dependent cases
outline the prognosis for cushing’s syndrome?
• Untreated - 5 yr survival = 50%
Depression persists for many years following treatment
what are the investigations for cushing’s syndrome?
urine pregnancy test
bloods
initial high sensitivity tests
tests to determine underlying cause ( measure plasma ACTH levels)
describe bloods in cushing’s syndrome?
U&Es - hypokalaemia due to mineralocorticoid effect
BM - high glucose
outline the initial high sensitvity tests for cushing’s syndrome?
24 hr Urinary free cortisol
9am cortisol
Late-night salivary cortisol
Overnight low-dose dexamethasone suppression test
▪ THIS IS USUALLY DONE
▪ 2mg dexamethanasone 11pm midnight
▪ Morning have blood test and failure to suppress cortisol
Low dose dexamethasone suppression test (LDDST)
▪ Give 0.5 mg dexamethasone orally ever 6 hrs for 48 hrs
In Cushing’s syndrome, serum cortisol measured 48 hrs after the first dose of dexamethasone fails to suppress below 50 nmol/L
what are the tests to investigate the underlying cause of cushing’s syndrome?
○ ACTH-dependent (pituitary adenoma)
▪ High plasma ACTH
▪ Pituitary MRI
▪ High-dose dexamethasone suppression test - uses 2mg which is capable of producing partial/complete suppression of cortisol if the problem is a pituitary tumour (since the pituitary retains some feedback control)
▪ Inferior petrosal sinus sampling (SUPERIOR to high-dose dexamethasone suppression test)
• Central: peripheral ratio of venous ACTH > 2:1 (or > 3:1 after CRH administration) in Cushing’s disease
○ ACTH-dependent (ectopic)
▪ an ectopic source of ACTH would not be responsive to exogenous feedback and so it’s not suppressed by the High-dose Dexamethasone suppression test
▪ If lung cancer suspected: CXR, sputum cytology, bronchoscopy, CT san
▪ Radiolabelled octreotide scans can detect carcinoid tumours because they express somatostatin receptors
○ ACTH-independent (adrenal adenoma/carcinoma)
▪ Low plasma ACTH
CT or MRI of adrenals
if the cause of cushion’s is iatrogenic- what should you do?
discontinue steroids, use lower dose or use a steroid-sparing agent
what are the 2 drugs used in the medical treatment of cushion’s syndrome?
metyrapone or ketoconazole
outline the medical management of cushing’s syndrome?
Used pre-operatively or if unfit for surgery
Inhibit cortisol synthesis with metyrapone or ketoconazole
Treat osteoporosis
Physiotherapy for muscle weakness