Intermittent Cushing's disease with spontaneous remission.

A patient with well documented Cushing's syndrome, associated with excessive secretion of ACTH, was studied over a 20 month period. During this time there were three episodes of spontaneous biochemical remission and except for a 7 day period of exacerbation the patient has had normal cortisol production for the last 15 months. During this recent prolonged remission period, repeat pituitary function testing demonstrated persistent abnormalities of the hypothalamic pituitary axis, in that ACTH failed to respond to a hypoglycaemic stimulus. However in all other respects adrenal function was normal with preservation of diurnal rhythmicity of cortisol and ACTH, and intact dexamethasone suppressability of cortisol. The additional unusual features of normal GH and TSH responses to stimulation, during either remission or exacerbation, suggest a subtle and localized hypothalamic defect in this case.