Low and high renin essential hypertension: a comparison of clinical and biochemical characteristics.

Based on a renin-sodium nomogram, patients with essential hypertension can be divided into low, normal and high renin subgroups. To define more clearly the clinical and biochemical characteristics of the two extreme groups, data of 83 patients with low renin essential hypertension were compared with those from 42 patients with high renin essential hypertension. In a further analysis, data or 27 age-and sex-matched patients from these two groups were compared with data from 27 matched subjects from a normotensive control group. Compared with high renin patients, low renin patients more frequently are female, older, and have higher systolic blood pressures and pulse pressures. The latter two characteristics are age-related. The similarity of duration of hypertension in both groups and the lack of correlation between age and plasma renin activity suggest that low renin hypertension is a separate entity rather than just a later phase of the same disease. Patients with low renin hypertension had better renal function than high renin patients or normotensive control subjects. High renin patients showed signs of hemoconcentration: hemoglobin, hematocrit, and total protein were higher than in low renin patients and normotensive controls. A significant difference between the slopes of the regression lines relating renin activity and sodium excretion for the two renin subgroups indicates that renin release in low renin patients is less sensitive to alterations in sodium balance. Both groups of patients had similarly elevated aldosterone levels, suggesting an increased sensitivity of aldosterone secretion to angiotensin II in low renin hypertensives. The relationship between aldosterone and potassium excretion was similar in both groups, indicating a comparable mineralocorticoid sensitivity.