Plasma Volume and Chronic Hypertension

Abstract

Plasma volume was measured with radioactive iodinated I 131 serum albumin in 80 normal subjects and 135 hypertensive patients without cardiac or renal failure, and results, expressed in milliliters per centimeter of body height, were correlated with weekly diastolic pressure averages (DBP). Plasma volume (PV) was reduced in renovascular hypertensive patients, whereas it correlated directly with DBP in hypertensive patients with renal parenchymal disease (r = 0.853, P<0.001). Plasma volume was normal in essential hypertensive men with DBP <105 mm Hg; those with higher pressures (30 patients) had either of two abnormalities: PV contraction in 22 (15.9 ml, P<0.01) and expansion in 8 (20.6 ml, P<0.05). Therapeutic response of these eight to spironolactone, thiazide diuretics, or both suggested they possibly represent a distinct hypertensive subgroup. Plasma volume and DBP correlated inversely (r = —0.646, P<0.05) in 11 patients with pheochromocytoma, but no correlation was obtained in 8 with primary aldosteronism, only 2 of whom had an expanded PV.