Pseudo-Cushing's syndrome

Pseudo-Cushing's syndrome is a medical condition in which patients display the signs, symptoms, and abnormal hormone levels seen in Cushing's syndrome. Pseudo-Cushing's syndrome, however, is not caused by a problem with the hypothalamic-pituitary-adrenal axis as Cushing's is. It is an idiopathic condition.

Investigations

• Levels of cortisol and ACTH are both high
• 24-hour urinary cortisol levels are high
• Dexamethasone suppression test fails to suppress serum cortisol
• Loss of diurnal variation in cortisol levels- Loss of Diurnal Variation is seen only in true Cushing's Syndrome or Disease.
• High mean corpuscular volume and gamma-glutamyl transferase may be clues to alcoholism
• Polycystic Ovarian Syndrome should be ruled out, since PCOS has similar symptoms.

Differential diagnosis

• Differentiation from Cushing's is extremely difficult
• Causes of Cushing's should be excluded with imaging of the lungs, adrenal glands, and pituitary gland - but these often appear normal in Cushing's anyway
• In the alcoholic patient with pseudo-Cushing's, admission to hospital (and avoidance of alcohol) will result in normal midnight cortisol levels within 5 days, excluding Cushing's

Prognosis

• Blood results and symptoms normalise rapidly on cessation of drinking or remission of depression