Sex differences in the endocrine predictors of essential hypertension. Vasopressin versus renin.

The relationships between arterial pressure (BP) and plasma vasopressin levels, plasma renin activity, and other variables were determined in 96 untreated essential hypertensive men (146/100 mm Hg) and women (153/102 mm Hg) whose average age was 44 years, 80 normal men and women (121/79 mm Hg; mean age, 47 +/- 2 years), and 40 subjects defined as borderline hypertensive. An analysis of variance indicated significant sex differences in the population. Levels of plasma vasopressin were significantly elevated in hypertensive men, with 26% (high plasma vasopressin hypertensive) exhibiting levels greater than 2 SD of the normal mean, and multivariate regression analysis indicated a significant positive correlation between plasma vasopressin levels and systolic and diastolic blood pressure. Hypertensive men had a larger daily urine volume than normal men. Diastolic pressure and heart rate were significantly elevated in a subgroup of 12 weight-matched and age-matched hypertensive men in the high plasma vasopressin group compared with levels in normal plasma vasopressin hypertensive men. Hypertensive women had lower plasma renin activity than normal women, and multivariate analysis indicated a significant negative correlation between plasma renin activity and systolic and diastolic blood pressure. Other significant abnormalities in both sexes were noted: hypertensive men and women weighed more and excreted more sodium per day, and both had higher heart rates. With a discriminant analysis of 18 variables in male subjects, plasma vasopressin levels, urinary sodium excretion, and heart rate correctly classified 71% of normal and hypertensive subjects. In women, plasma renin activity, urinary sodium excretion, and heart rate correctly classified 77% of normal and hypertensive subjects. Despite the inability to ascertain causal relationships, the ability of the three variables in combination to correctly classify normal and hypertensive subjects indicates that these combined variables are reproducibly altered in persons with essential hypertension.