Prompt differentiation of Addison's disease from anorexia nervosa during weight loss and vomiting

An 18-year-old white woman had nausea, vomiting, weight loss, and a diagnosis of anorexia nervosa. Copper-colored skin was noted on physical examination, and serum chemistry values were normal. Subsequent fever, disorientation, and confusion led to the discovery of Addison's disease, which responded well to corticosteroid replacement therapy. Addisonian and anorexic patients exhibit clinical similarities, including nausea, vomiting, weight loss, abdominal pain, cold intolerance, hypothermia, and orthostasis. Other commonalities include prolongation of electrocardiographic PR and QT intervals and generalized slowing on electroencephalogram. Important differences include a brown color to the skin in Addison's disease instead of a yellowish color in anorexia. Addisonian patients also display hypocortisolism, hypoglycemia, and hyperkalemia, in contrast to the hypercortisolism, hyperglycemia, and hypokalemia seen in anorexia.