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. However, pseudo-Cushing's syndrome is not caused by a problem with the hypothalamic-pituitary-adrenal axis as Cushing's is; it is mainly an idiopathic condition, however a cushingoid appearance is sometimes linked to excessive alcohol consumption. Elevated levels of total cortisol can also be due to estrogen found in oral contraceptive pills that contain a mixture of estrogen and progesterone. Estrogen can cause an increase of cortisol-binding globulin and thereby cause the total cortisol level to be elevated.

Diagnosis

• Levels of cortisol and ACTH both elevated
• 24-hour urinary cortisol levels elevated
• Dexamethasone suppression test
• Late night salivary cortisol (LNSC)
• 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 may have 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 adrenocortical carcinoma. This is a rare form of cancer with an incidence of 1-2 per million people annually. About 60% of these cancers produce hormones, with cortisol being the most frequent. Most patients present in an advanced disease state and the outcome is dismal.

Prognosis

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