A 55-year-old man has experienced increasing lethargy for the past 7 months. Physical examination shows the hyperpigmentation of the skin. Vital signs include a temperature of 36.9degC, pulse of 70/min, respirations of 14/min, and blood pressure of 95/65 mm Hg. Laboratory studies include a serum cortisol level of 3 mg/mL at 8:00 A.M. with a serum corticotropin level of 65 pg/mL. Which of the following diseases most often occurs in patients with this disorder?

Addison disease (primary chronic adrenocortical insufficiency) most often results from an idiopathic autoimmune condition (in areas of the world where the incidence of active tuberculosis is low). Autoimmune adrenalitis is associated with the appearance of other autoimmune diseases in about half of all cases. Such autoimmune phenomena are frequently seen in other endocrine organs, such as the thyroid gland. Other presumed autoimmune diseases, such as systemic lupus erythematosus, ulcerative colitis, and the vasculitides, are usually not forerunners to adrenal failure, although treatment of these conditions with corticosteroids can lead to iatrogenic adrenal atrophy. Type 2 diabetes mellitus, unlike type 1, does not have an autoimmune basis.