Comparison of the effects of diuretic therapy and low sodium intake in isolated systolic hypertension.

Of 103 patients with isolated systolic hypertension, 71 were treated with diuretics and another 32 with low-sodium diet. In the 71 who were treated with diuretics, body weight decreased from 69.48 +/- 1.47 to 68.60 +/- 1.45 kg (p less than 0.0005) and systolic blood pressure from 178 +/- to 152 +/- 2 mm Hg (p less than 0.0005). Plasma renin activity increased from 1.78 +/- 0.30 to 7.32 +/- 1.78 ng/ml per hour (p less than 0.005) and urinary aldosterone from 10 +/- 1 to 23 +/- 4 micrograms per 24 hours (p less than 0.005). The greatest decrease in systolic blood pressure occurred in patients in the low-renin group (-32 +/- 2 mm Hg), whereas it decreased by 24 +/- 2 mm Hg (p less than 0.04) in the normal-renin group; however, blood pressure did not change significantly in the high-renin group. In the 32 patients who were treated with low-sodium diet, the 24-hour urinary sodium excretion decreased from 143 +/- 10 to 48 +/- 5 meq (p less than 0.005), body weight decreased from 71.18 +/- 2.50 to 70.17 +/- 2.47 kg (p less than 0.005), systolic blood pressure decreased from 174 +/- 2 to 156 +/- 3 mm Hg (p less than 0.0005), and diastolic blood pressure decreased from 90 +/- 1 to 87 +/- 1 mm Hg (p less than 0.01). Plasma renin activity increased from 2.25 +/- 0.33 to 4.27 +/- 0.43 ng/ml per hour (p less than 0.005) and urinary aldosterone from 9 +/- 1 to 15 +/- 2 micrograms per 24 hours (p less than 0.005). The decrease in the systolic blood pressure was related to the pretreatment 24-hour urinary sodium excretion (r = 0.40, p less than 0.05). The smallest decrease in systolic blood pressure occurred in the patients with high renin values (-1 +/- 9 mm Hg, n = 5), whereas the decrease in systolic blood pressure in the low-renin (n = 12) and normal-renin groups (n = 15) was similar, -22 +/- 2 mm Hg and -21 +/- 3 mm Hg, respectively (p less than 0.005 compared with the high-renin group). These results indicate that both diuretic therapy and low-sodium diet are effective antihypertensive means in most patients with isolated systolic hypertension and low or normal plasma renin activity.