The most common cause of Addison's disease is:

Primary Chronic Adrenocoical Insufficiency (Addison Disease) Uncommon disorder resulting from progressive destruction of the adrenal coex More than 90% of all cases are attributable to one of four causes: Autoimmune adrenalitis Accounts for 60% to 70% of cases; it is by far the most common cause of primary adrenal insufficiency in developed countries Infections Paicularly tuberculosis and those produced by fungi- histoplasmosis, AIDS Tuberculous adrenalitis, which once accounted for as much as 90% of cases of Addison disease, has become less common with the development of antituberculous agents Genetic conditions - Adrenogenital syndromes Metastatic cancers.