Cushings Syndrome Flashcards
What is Cushings syndrome?
Cushing syndrome is the clinical manifestation of pathological hypercortisolism from any cause.
Epidemiology of Cushings
- Cushing’s syndrome is uncommon, with an estimated 1-10 cases per million in the population
- It most commonly affects people aged 20 to 50 years
- Occurs 3 times more commonly in women than in men
What is Cushings disease?
a pituitary adenoma secreting excess ACTH
Aetiology of Cushings other than Cushings disease
- Iatrogenic - due to exogenous steroid use
- Primary disease - e.g. adrenal adenoma or adrenal hyperplasia - secreting excess cortisol
- Paraneoplastic Cushing’s- cancer producing ectopic ACTH e.g. from small cell lung cancer or neuroendocrine tumours
- Carney complex - a genetic disorder with multiple benign tumours, e.g. cardiac myxoma
- Micronodular adrenal dysplasia - rare cause
RFs for Cushing’s
- Long term steroid use
- Pituitary adenoma
- Adrenal adenoma
- Small cell lung cancer
- Neuroendocrine tumours
Signs of Cushings
- Hypertension
- Moon face
- Buffalo hump
- Central adiposity
- Violaceous striae
- Muscle wasting and proximal myopathy
- Ecchymoses and fragile skin
- Acne
Symptoms of Cushings
- Bloating and weight gain
- Mood change
- Tiredness
- Easy bruising
- Increase susceptibility
- Menstrual irregularity
- Reduced libido
1st line investigation for Cushings
- 24-hour urinary free cortisol
- Overnight dexamethasone suppression test:most sensitive; shows failure of cortisol suppression
- Low dose dexamethasone suppression test:shows failure of cortisol suppression
- Late-night salivary cortisol - helps to demonstrate a loss of the normal circadian pattern.
Any of these is fine
Gold standard investigation for Cushings
- 24-hour urinary free cortisol
- Overnight dexamethasone suppression test
What will a 9am ACTH test show?
- Ifelevated: suggests anACTH-dependentcause and warrants ahigh dose dexamethasone suppression test
- Iflow: suggests anACTH-independentcause and warrants aCT adrenalsto look for adrenal pathology
What will a High dose dexamethasone suppression test show
suppression of cortisol occurs in Cushing’s disease (pituitary adenoma), butnotin an ectopic ACTH source
Differential Diagnosis for Cushings syndrome
- Obesity
- Metabolic syndrome
Management of ACTH - dependent cause
- Cushing’s disease (pituitary adenoma):first-line treatment is withtrans-sphenoidal resectionof the pituitary. There is a role for medical therapy (e.g. glucocorticoid antagonists) or radiotherapy if surgery fails
- Ectopic ACTH source:treatment of underlying cancer
Management of ACTH-independent causes
- Iatrogenic:review the need for medication and try weaning if possible
- Adrenal tumour:tumour resection or adrenalectomy - Unilateral adrenal adenoma, Bilateral adrenal hyperplasiam adrenal carcinoma
Treatment for unilateral adrenal adenoma
Unilateral adrenalectomy offers curative therapy
Following surgery patients will need a tapering course of exogenous steroids for a period of time as their endogenous CRH and ACTH will be suppressed.
