Dihydroxyphenylglycol (
DOPEG) is a metabolite of
noradrenaline (NA) in the sympathetic nerve endings, and dihydroxymandelic
acid (DOMA) is one in the extraneuronal tissues. The measurement of plasma
DOPEG and DOMA were evaluated with NA as one of the clinical indices of sympathetic nerve activity. These were measured in
essential hypertension and also applied for diagnosis of
pheochromocytoma. Plasma
DOPEG levels were correlated with NA. Plasma NA and
DOPEG were decreased after
oral administration of
clonidine (150 micrograms) and plasma
DOPEG levels were slowly increased after standing. Therefore, plasma
DOPEG seemed to be useful as one of the rather stable indices of the sympathetic nerve activity. Plasma NA and
DOPEG levels in WHO stage I
essential hypertension were higher than those in normotensive controls. Observed normal plasma
noradrenaline and
DOPEG levels in stage II reflect the normalized sympathetic tone in this stage. The elevation of plasma NA and DOMA levels in stage III seemed to be at least partly explained by renal function disturbance. In patients with
pheochromocytoma, despite of the marked elevation of plasma NA and DOMA, plasma
DOPEG showed only three-fold elevation and the ratio
DOPEG/NA was reduced. The simultaneous measurement of plasma NA,
DOPEG and DOMA is useful to evaluate sympathetic nerve activity in
essential hypertension and to differentiate
pheochromocytoma in
hypertension.