Dopamine-beta-hydroxylase. An index of adrenergic function in hypertensive patients.

Previous attempts to assess sympathetic nervous system activity in patients with hypertension have used a variety of physiologic, pharmacologic and biochemical techniques. Results have been conflicting and confusing. Recently, the activity in plasma of the catecholamine synthesizing enzyme, dopamine-beta-hydroxylase (DBH), has been proposed as an index of sympathetic nervous system activity. Studies of apparently healthy subjects show that high values (greater than 60 units per liter) for plasma DBH activity correlate with pronounced daily lability of blood pressure and frequent readings greater than 130/85 mm of mercury. Studies of patients referred for evaluation of established hypertension show significantly higher values for plasma DBH activity in patients with primary hypertension than in those with commonly recognized forms of secondary hypertension-that is, renovascular, renal parenchymal and adrenocortical. Therefore, the measurement of plasma DBH activity may be helpful in the study and differential diagnosis of hypertensive diseases. Measurement of DBH in plasma is inexpensive, reproducible and relatively easy to do.