Responses to volume expansion and contraction in categorized hypertensive and normotensive man.

SUMMARY We examined tbe responses to volume expansion and contraction in normals, essential hypertensives, and patients with secondary hypertension, in order to formulate a more precise method of categorizing essential hypertensives with respect to plasma renin and aldosterone responses. We studied 379 normal and 464 hypertensive patients during and after a 4 hour 2 liter intravenous saline infusion, and after 120 mg oral furosemide. The large number of normal white and black subjects permitted renin profiling according to race and age. Of 395 essential hypertensives, 12% were categorized as having low-renln, 72% normal-renln, and 16% high-renln hypertension. Our results show, when tbe renin values are adjusted for age and race, lowrenin hypertension in blacks and the elderly is less common than previously described. The most useful clinical information obtained was from measurements of plasma renin activity and aldosterone concentration following saline infusion, since that maneuver identified all patients with high-renin hypertension and also the 25 patients with primary aldosteronism. The 44 patients with renal vascular hypertension could not be identified on the basis of their renin and aldosterone responses. Tbe natriuretic and kalluretic responses during saline infusion were much greater in patients with primary aldosteronism than in other hypertensive subgroups or normal subjects. The magnitude of these responses may be of value in suggesting the diagnosis in situations where plasma aldosterone measurements are not readily available.