Idiopathic isolated ACTH deficiency and the response to CRF

A 26-year-old woman, intermittently symptomatic over 8 yr, was evaluated for weakness, lightheadedness, and gastrointestinal complaints. She was found to have negligible plasma cortisol and low to low-normal plasma ACTH levels. Although serum cortisol was responsive to ACTH stimulation, metyrapone and insulin-induced hypoglycemia were unable to stimulate pituitary driven adrenal activity. Hypothalamic and pituitary functions were otherwise intact. CRF administration failed to stimulate any increase in plasma ACTH or cortisol levels and CT scanning failed to reveal any anatomic abnormality of the sella or suprasellar areas consistent with an acquired isolated defect in pituitary ACTH secretion. These studies support the impression that the primary defect in isolated idiopathic ACTH deficiency is failure of pituitary ACTH-secreting cells.