Plasma catecholamines and essential hypertension. An analytical review.

Of 78 comparative studies of plasma catecholamines in patients with essential hypertension and in normotensive controls, most reported higher catecholamine levels in the hypertensives, although only about 40% of the studies were positive (reporting statistically significant hypertensive-normotensive differences). Although there was dramatic variability in catecholamine values within and across studies, virtually all studies of norepinephrine in young, consistently hypertensive patients were positive. The likelihood that a study was positive with respect to norepinephrine was independent of the likelihood with respect to epinephrine, so that total catecholamine values, or else the sum of norepinephrine plus epinephrine, differentiated hypertensives from normotensives to a greater extent than levels of either substance alone. The preponderance of literature on the subject supports the hypothesis that increased plasma catecholamine concentrations occur in some patients with essential hypertension. Elevated plasma norepinephrine in relatively young, established hypertensive patients is consistent with a pathophysiologic role for increased sympathetic neural activity in this subgroup.