differential diagnosis

Last reviewed 01/2018

  • pseudo Cushing's due to alcohol - centripetal obesity, plethora, hypertension, elevated urinary free cortisol - check past history, habit, abnormal liver function tests, raised mean cell volume or blood alcohol - biochemical abnormalities may resolve in hospital with no alcohol
  • pseudo Cushing's due to depression - insulin tolerance test is often discriminatory:
    • depressed patients show normal rise in cortisol
    • Cushing's syndrome patients are insulin resistant and show no rise in plasma cortisol
  • glucocorticoid resistance syndrome - basal ACTH and cortisol elevated and only partially suppressible with dexamethasone
  • investigations may be misleading in patients with severe intercurrent illness or on enzyme inducing drugs such as phenytoin