The role of epinephrine, norepinephrine, and dopamine in blood pressure disturbances in patients with pheochromocytoma.

Fifty-six patients with pheochromocytoma underwent surgery during the 9-year period from 1981 to 1990. These patients were divided into two groups according to whether the dominant plasma concentration was of epinephrine or norepinephrine. Plasma levels of the catecholamines were stratified into three grades at 5 and 10 times the normal upper limit. Pre-operative disturbances of blood pressure, sustained or paroxysmal, and normal blood pressure were highly correlated with the dominantly secreted catecholamine and its plasma concentration. Thirteen patients with high plasma norepinephrine levels (greater than or equal to 10 times normal) had sustained hypertension while 18 patients with moderate to high plasma epinephrine levels (greater than or equal to 5 times normal) had paroxysmal hypertension. In the majority of normotensive patients (12 of 14), plasma catecholamine levels were less than 10 times the upper normal limit. Urinary excretion of dopamine and size of the tumor were analyzed according to these patient groups. In the norepinephrine dominant group, urinary dopamine excretion tended to be proportional to the plasma epinephrine levels and when the patients were normotensive, urinary dopamine excretion decreased. In norepinephrine-secreting patients, urinary dopamine tended to be inversely correlated with the plasma norepinephrine level; however dopamine did not prevent the hypertensive action of norepinephrine. Tumor size showed no correlation with the plasma levels of catecholamine in the moderate to high plasma catecholamine groups. We conclude that the plasma catecholamine type and its level are the most important factors in determining the patterns of blood pressure disturbances of patients with pheochromocytoma.