Plasma catecholamines after insulin hypoglycemia in Sheehan's syndrome

The plasma catecholamine response to hypoglycemia was studied in a group of hypopituitary patients with Sheehan's syndrome before (group A) and after (group B) combined cortisol and thyroid hormone treatment as well as in a group of normal women (group C). The mean basal plasma norepinephrine (NE) level was significantly increased in group A compared to levels in groups B and C, in which values were similar. The mean basal plasma epinephrine (E) level was not significantly altered by hypopituitarism. The plasma NE response to hypoglycemia was similar in the three groups, while the plasma E response was blunted in groups A and B. However, the plasma E response was significantly decreased only in half of the patients. The basal E/NE ratio was similar in the three groups, but it was significantly decreased in groups A and B compared to that in group C at the peak. From these data we conclude that 1) hypopituitarism is characterized in the basal state by increased adrenergic tone, probably related to secondary hypothyroidism; and 2) during hypoglycemia adrenal stimulation is impaired only in some patients. The role of ACTH in the regulation of E secretion is minor. Impaired neurogenic regulation in some patients with Sheehan's syndrome could contribute to their illness.