Plasma aldosterone concentration / plasma renin activity ratio in patients with essential hypertension before treatment

Abstract

Abstract Background The renin–angiotensin–aldosterone-sodium system, an important player in maintaining blood pressure, is influenced by antihypertensive drugs. However, the analysis of the renin-aldosterone-sodium system in hypertensive patients without adrenal adenoma without antihypertensive drugs is not still enough. Purpose We analyzed plasma aldosterone level, renin activity, serum potassium level, and serum sodium level in hypertensive patients without adrenal adenoma before treatment. Methods We measured plasma aldosterone concentration (PAC; pg/mL), plasma renin activity (PRA; ng/mL/h), serum potassium and sodium levels (mEq/L) in 456 consecutive new hypertensive patients untreated with antihypertensive drugs. We sampled all blood after 30 minutes bedrest. We excluded 28 cases with blood pressures less than 135/85 mmHg at rest, 4 patients with adrenal adenoma, and 3 patients with renovascular hypertension. We analyzed 421 patients with essential hypertension before treatment (232 males, mean age 56.5±12.8 years, and 189 females, mean age 61.0±13.5 years). Results There was a significant positive correlation between PRA and PAC (ρ=0.2445, p<0.001). There was a significant positive correlation between PAC/PRA ratio and serum sodium levels (ρ=0.1604, p=0.0027); however, no correlation was observed between PAC/PRA ratio and serum potassium levels. There were significant negative correlations between PRA and serum sodium levels (ρ=-0.1925, p<0.001). However, there was no correlation between PAC and serum sodium levels. On univariate analyses, a high PAC/PRA ratio (>200) was significantly associated with female (p<0.001), high serum sodium level (p=0.003), and low pulse rate (p=0.02). Multiple logistic analyses revealed that the most predictive independent factor for high PAC/PRA was female (p<0.001). On analyses of gender differences, the incidence rates of high PAC/PRA (>200) were 33.9% in females and 16.4% in males. There was a significant positive correlation between PRA and PAC in both genders (males: ρ=0.2731, p<0.001; females: ρ=0.1976, p=0.0064). In females, there was a significant positive correlation between PAC/PRA and serum sodium levels (ρ=0.2221, p=0.0043); however, there were no significant correlations between PAC/PRA and serum sodium levels in males. In females, there was a significant negative correlation between PRA and serum sodium levels (ρ=-0.2668, p<0.001); however, there were no significant correlations between PRA and serum sodium levels in males. Serum sodium levels were significantly higher in females than in males (p=0.02). Conclusion We revealed gender differences in the renin-aldosterone-sodium system in patients with essential hypertension before treatment.