Free and conjugated plasma catecholamines in pheochromocytoma patients with and without sustained hypertension

Ten pheochromocytoma patients, five with paroxysmal hypertension (Group 1), five with sustained hypertension (Group 2) and 15 normals were studied to determine the relationship between differential secretion of the catecholamines (CA) or differences in their sulphoconjugation and the hypertension patterns in these patients. Group 1 patients were studied in the normotensive period. A consistent finding in this study is that permanent hypertensive patients showed the highest free and conjugated norepinephrine (NE) levels while paroxysmal patients studied during the normotensive period showed the highest conjugated epinephrine (E) levels. Although no significant difference was found in levels of free plasma epinephrine in the Group 1 patients, in the ratio of total plasma E/NE, E was clearly predominant. No significant differences could be found in the degree of the per cent conjugation of individual catecholamines between both groups of patients. Group 1 showed a higher (P less than 0.05) E and a lower dopamine (DA) per cent conjugation than controls. In conclusion, although the dominant type of CA secreted seems to be the main factor in determining the hypertension pattern, sulphoconjugation ability may also play an important role.