A case of initially undiagnosed hypoadrenalism presenting inappropriate secretion of anti-diuretic hormone

The case of a 55-year-old woman with inappropriate secretion of anti-diuretic hormone (ADH) is reported. Her pituitary-adrenocortical function test showed normal values on admission, but when she recovered from hyponatremia, severe panhypopituitarism became overt. Her adrenal insufficiency was considered to have been ''masked'' by endogenous stimulation of the hypothalamus-pituitary-adrenal axis under severe stress. One should be cautious in estimating the pituitary-adrenal function of severely ill patients.