Cushing's syndrome

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Contents

Introduction

An eponymous syndrome after the Boston Neurosurgeon Harvey Cushing relating to cortisol excess. Also see Cushing's disease

Aetiology

Excess circulating glucocorticoids.

In Cushing's disease this is caused by excess pituitary ACTH production. In adrenal Cushing's syndrome this is usually caused by gain of function variants of PRKACA. Ectopic ACTH can be produced by tumours.

Clinical

Less commonly

Investigations

Blood tests

U&E

  • Sodium retention
  • Potassium loss
  • Hypokalaemic alkalosis

Low dose dexamethasone suppression test. ( Dexamethasone 1mg orally @ midnight, serum cortisol @ 09:00. If <50mmol/L excludes diagnosis)

High dose dexamethasone suppression test

Radiology

Treatment

Medical

Stop or minimize exogenous steroids

Surgical

If no exogenous steroids in use suspect Cushing's disease or steroid /ACTH secreting tumour may require surgical intervention

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