Patients with low-renin essential hypertension had significantly higher plasma volume, extracellular fluid volume, and total exchangeable sodium compared to normal- and high-renin groups.
Cross-Sectional
Low-renin essential hypertension is characterized by higher plasma and extracellular fluid volumes and total exchangeable sodium compared to normal- and high-renin hypertension.
Plasma volume (PV), extracellular fluid volume (ECFV) and total exchangeable sodium (Nae) were measured by the dilution methods of 131RISA and 22NaCl in the patients with low-(LRH), normal-(NRH) and high-renin essential hypertension (HRH). In addition, fractional excretion of sodium (FENa) and inorganic phosphorus (FEP) and free water (FEW), urinary Na/K ratio after oral water ingestion of 400 ml/m2 body surface area, and fractional potassium excretion (FEK) after intravenous injection of 80 ml of 10% sodium thiosulfate, estimated by clearance method, were compared between LRH and NRH. PV, ECFV and Nae, which inversely correlated with logarithm of supine plasma renin activity (log PRA), were significantly higher in LRH than each of NRH and of HRH. FENa and FEP, which are assumed to reflect the renal tubular and proximal tubular sodium reabsorption, were positively correlated with age, severity of hypertension (VA score), mean arterial pressure (MAP) and correlated inversely with endogenous creatinine clearance (Ccr). FENa was also correlated positively with log PRA and negatively with ECFV and Nae in the whole patients with essential hypertension. Twenty-four hour urinary kinins excretion and plasma levels of antidiuretic hormone (ADH) measured by radio immunoassay were compared between LRH and NRH. LRH had significantly lower FENa and FEP than age-, MAP- and Ccr-matched NRH and lower urinary excretion of kinins than age-matched NRH. The mean values of these variables in LRH are almost similar to those in normotensive subjects. Plasma ADH levels and FEW were significantly lower and tended to be lower than those in NRH, respectively. Urinary Na/K ratio and FEK which may reflect the mineralocorticoid action on the renal tubule were not significantly different among these three renin sub-groups.
Kikuchi et al. (1979) conducted a cross-sectional in Essential hypertension. Low-renin essential hypertension vs. Normal- and high-renin essential hypertension was evaluated on Plasma volume, extracellular fluid volume, and total exchangeable sodium. Patients with low-renin essential hypertension had significantly higher plasma volume, extracellular fluid volume, and total exchangeable sodium compared to normal- and high-renin groups.