Most common cause of adrenal insufficiency is

(C) Autoimmunity # Primary adrenal insufficiency is most commonly caused by autoimmune adrenalitis. Isolated autoimmune adrenalitis accounts for 30-40%, whereas 60-70% develop adrenal insufficiency as a part of autoimmune polyglandular syndromes (APS). APS1, also termed APECED (autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy), is the underlying cause in 10% of patients affected by APS# Classification of Adrenal insufficiency> Primary Adrenal Insufficiency: Anatomic destruction of gland (chronic or acute) "Idiopathic" atrophy (autoimmune, adrenoleukodystrophy) Surgical removal Infection (tuberculous, fungal, viral--especially in AIDS patients) Hemorrhage Invasion: metastatic Metabolic failure in hormone production Congenital adrenal hyperplasia Enzyme inhibitors (metyrapone, ketoconazole, aminoglutethimide) Cytotoxic agents (mitotane) ACTH-blocking antibodies Mutation in ACTH receptor gene Adrenal hypoplasia congenita> Secondary adrenal Insuffiency: Hypopituitarism due to hypothalamic-pituitary disease Suppression of hypothalamic-pituitary axis By exogenous steroid, by endogenous steroid from tumor