Adrenal insufficiency is a rare endocrine disorder, characterized by an inappropriate secretion of adrenal hormones. It can be caused either by adrenal failure (Addison’s disease, primary adrenal insufficiency) or by dysfunction of the integrity of the hypothalamic-pituitary-adrenal axis (secondary adrenal insufficiency). Primary adrenal insufficiency occurs with an estimated prevalence of 93–140 per million and is less frequently diagnosed than secondary adrenal insufficiency (prevalence of 150–280 per million) . In the developed world, primary adrenal insufficiency most frequently stems from autoimmune adrenalitis, whereas in the developing world, infectious diseases such as tuberculosis or cytomegalovirus play a substantial etiological role. Pituitary adenomas and its treatment (surgical removal or radiation therapy) present the main causes of secondary adrenal insufficiency.