Pseudo-Cushing's syndrome

Pseudo-Cushing's syndrome
Classification and external resources
ICD-10	E24.3
eMedicine	med/1936

Pseudo-Cushing's syndrome is a medical condition in which patients display the signs, symptoms, and abnormal hormone levels seen in Cushing's syndrome. However, pseudo-Cushing's syndrome 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 both elevated
• 24-hour urinary cortisol levels elevated
• Dexamethasone suppression test fails to suppress serum cortisol
• Loss of diurnal variation in cortisol levels (seen only in true Cushing's Syndrome)
• High mean corpuscular volume and gamma-glutamyl transferase may be clues to alcoholism
• Polycystic Ovarian Syndrome should be ruled out; PCOS has similar symptoms

Differential diagnosis

• Differentiation from Cushing's is difficult, but several tools exist to aid in the diagnosis
• Alternative causes of Cushing's should be excluded with imaging of lungs, adrenal glands, and pituitary gland; these often appear normal in Cushing's
• In the alcoholic patient with pseudo-Cushing's, admission to hospital (and avoidance of alcohol) will result in normal midnight cortisol levels within five days, excluding Cushing's
• Another cause for Cushing's syndrome is the extremely rare form of cancer (Adrenal Cortisol Carcinoma), when a benign lesion on the adrenal gland (which would cause Cushing's) becomes malignant and starts producing its own cortisol. This produces Cushing's-like symptoms and is fatal. Life expectancy depends on early detection. Ruling out ACC is done with a CT scan of the abdomen, identifying the size and location of adrenal tumors and lesions.

Prognosis

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