[Isolated ACTH deficiency associated with Hashimoto disease].

Isolated ACTH deficiency is a rare cause of secondary adrenocortical insufficiency. The diagnosis is made by the demonstration of low cortisol production with low plasma ACTH, absent adrenal responses to stimulation for pituitary or hypothalamus with intact adrenal response to exogenous ACTH, and normal secretory indices of other pituitary hormones. Although the pathogenesis of isolated ACTH deficiency is uncertain in most cases, autoimmune process is intimately involved as suggested by the histological evidence of lymphocytic hypophysitis and frequent observation of circulating antipituitary antibodies. In isolated ACTH deficiency, there have been occasional associations with Hashimoto disease which is characterized by the presence of a autoimmune mechanism. This suggests the possibility of common autoimmune process affecting both the pituitary and the thyroid gland.