Hormone secretion in alcohol-induced pseudo-Cushing's syndrome. Differential diagnosis with Cushing disease

We describe the clinical and biochemical characteristics of alcohol-induced pseudo-Cushing's syndrome in two patients with signs and symptoms of Cushing's syndrome and slight disturbances in liver function. An insufficient suppression of plasma cortisol to the overnight administration of 1 mg of dexamethasone was accompanied by an absent diurnal rhythm of plasma cortisol and an increased cortisol secretion rate. The plasma cortisol levels at 8 AM normalized during hospital admission (ie, alcohol withdrawal) at the same rate or parallel with the serum gamma-glutamyl transferase concentration. A normal increase of plasma cortisol, adrenocorticotropic hormone, and growth hormone in response to an insulin induced hypoglycemia was not compatible with the diagnosis Cushing's syndrome. However, the result of a differential diagnostic test with metyrapone was compatible with the presence of Cushing's disease. An erroneous diagnosis of Cushing's disease can be easily made in patients with alcohol-induced pseudo-Cushing's syndrome.