Functional correlates of plasma renin activity in hypertensive patients.

Correlates of peripheral plasma renin activity were studied in 31 normotensive subjects and 93 untreated hypertensive patients. The latter were grouped according to apparent type of hypertension: essential (58), renovascular (21), renal parenchymal disease (11), and primary aldosteronism (3). Plasma renin activity was inversely correlated with total blood and plasma volumes in normal men, men with essential hypertension, and patients with renal arterial stenosis; no correlations were found in normal and essential hypertensive women and patients with renal parenchymal disease. Serum sodium and potassium concentrations were significantly and inversely related to renin activity only in renovascular hypertension and not in the other hypertensive or normal groups. Relationships of plasma renin activity to arterial pressure and other hemodynamic functions were studied in hypertensive patients. Only in the renovascular group did diastolic pressure correlate positively and significantly, indicating participaton of the renal pressor system in this form of hypertension throughout a wide range of pressures. Cardiac index and left ventricular ejection rate were directly related to renin activity in essential hypertensive men and patients with renal arterial and parenchymal diseases. The data show that plasma renin activity in hypertensive patients should not be judged alone but along with factors modifying it.