Abnormalities of Plasma Volume in Borderline Hypertension

Abstract

(Fig 1). Con¬ versely, the hematocrit reading was significantly higher in borderline hy¬ pertension.Since the decreased plasma volume is considered the main finding of this study, it will be further analyzed in respect to its reproducibility, its rela¬ tionship to body weight, and its rela¬ tionship to other hemodynamic mea¬ surements.Reproducibility of the Plasma Vol¬ ume Measurement.- Figure 2 shows plasma volume measurement re¬ peated in ten patients whose first de¬ termination was in the lower two thirds of the original sample. The second determination was taken from 6 to 60 weeks after the initial measurement.

Elevated blood viscosity in patients with borderline essential hypertension.

“…5 -6 Plasma volume may be normal or decreased. 7 Plasma renin activity (PRA) and 24-hour urinary sodium excretion are related in a manner similar to that found in patients with established hypertension. 8 -9 By mechanisms that remain incompletely understood, total peripheral resistance is abnormally elevated in relation to systemic blood flow.…”

Obesity Paradox in Hypertension

“…108 In both studies, reduction achieved in clinical cardiovascular end points, at similar blood pressure reduction, was materially worse with diuretic treatment in lean compared with obese hypertensive patients. It can be argued that this unexpected result was caused by a reactive stimulation of the sympathetic and renin-angiotensin systems by diuretic-induced natriuresis 109 in normal-weight patients, who untreated have reduced plasma volume, 110 in contrast with obesity-hypertension, in whom volume expansion is common. On the basis of the existing sympathetic activation phenotypes, and sympathetic augmentation with diuretic treatment, 109 a case can be made for the preference of antiadrenergic antihypertensive drugs in normal-weight hypertension and diuretics in obesity-hypertension.…”

Autonomic imbalance, hypertension, and cardiovascular risk

“…129,130 This is typically explained to be the result of the decreased plasma volume that occurs in hypertension. 131,132 High sympathetic tone via ␣-receptor-mediated postcapillary venule constriction results in translocation of approximately 500 mL of plasma into the interstitial space. Experimentally this has been demonstrated by infusions of norepinephrine 133 and by unopposed ␣-activity generated by ␤-blockers in human subjects.…”