The Adrenal Medullary Response to Hypoglycemia in Patients with Orthostatic Hypotension

The epinephrine response to insulin-induced hypoglycemia has been studied in patients with orthostatic hypotension and in control subjects. Normal subjects had a brisk increase in plasma epinephrine and norepinephrine levels which occurred at the nadir of plasma glucose levels. After the nadir of hypoglycemia, glucose recovery was biphasic, with an initial rapid rise in glucose, followed by a more gradual return to normoglycemia. In a group of 16 patients with orthostatic hypotension, 12 had deficient plasma catecholamine responses to hypoglycemia, and of these, 7 had almost no plasma epinephrine response. Comparison of the plasma epinephrine responses and the course of plasma glucose elevations indicated that a mean plasma epinephrine level of over 200 pg/ml is necessary for the rapid initial phase of glucose recovery. There does not appear to be any relationship between the etiological basis of the autonomic dysfunction and deficient epinephrine response.