THE ESTIMATION OF EPINEPHRINE AND NOREPINEPHRINE IN HUMAN PLASMA*

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Abstract
A modification of the ethylenediamine technic for the measurement of plasma epinephrine and norepinephrine is described, and the results of studies in normal subjects and patients are reported. Normal subjects had higher norepinephrine levels during mild activity than at bed rest, and an increase in both epinephrine and norepinephrine levels was observed after strenuous exercise. The plasma concentration of epinephrine was elevated during hypoglycemia following the administration of insulin to a normal subject. The concentrations of plasma amines in patients with essential hypertension, diabetes, adrenal insufficiency or hypopituitarism were not significantly altered. However, an elevation of epinephrine level was observed in patients with hyperthyroidism. The results of studies performed in 9 patients with pheochromocytoma confirmed the usefulness of plasma amine determinations in the diagnosis of this disorder, and showed a high correlation between the proportions of epinephrine and norepinephrine in plasma and tumor. Increased concentrations of plasma amines following injection of histamine were observed in patients with paroxysmal hypertension due to pheochromocytoma, but not in patients with essential hypertension. The ethylenediamine method appears most useful for the detection of elevations in the plasma epinephrine and norepinephrine levels in patients with pheochromocytoma and for the detection, by repeated sampling, of changes occurring over short periods of time in a specific subject.