Pseudo-Addison's disease. Isolated corticotropin deficiency associated with hyporeninemic hypoaldosteronism

A 60-year-old man presented with loss of weight and appetite, eosinophilia, and hyperkalemia consistent with a diagnosis of Addison's disease. Adrenal responsiveness to exogenous corticotropin was normal, but endogenous corticotropin and cortisol responses to insulin-induced hypoglycemia were both absent. Pituitary function was otherwise intact. Renin and aldosterone levels were subnormal and did not respond to postural change. To our knowledge, this is the first reported case of isolated corticotropin deficiency and hyporeninemic hypoaldosteronism together mimicking primary adrenocortical failure.