Pituitary-adrenocortical system in patients with Shy-Drager syndrome.

We examined ACTH responses to the three main mechanisms of ACTH secretion, i.e., stress, negative feedback and circadian rhythm, in six patients with Shy-Drager syndrome and in six control subjects to determine whether or not injury to the central autonomic nervous system provokes some disturbances in ACTH secretion. The patients showed a poor cortisol response to the stress of insulin induced hypoglycemia along with a normal ACTH and urinary 17-OHCS response to metyrapone and a normal cortisol circadian rhythm. The discrepancy between the above-mentioned functional tests of ACTH secretion is rare to our knowledge. These findings suggested the existence of a glucoreceptor defect in such patients, or the possibility that the stress of insulin induced hypoglycemia stimulates ACTH secretion by way of the autonomic nervous system.