P-573: Moderate salt restriction effectively lowers blood pressure and degree of salt sensitivity is predicted by plasma renin in Swedish subjects with normal and slightly elevated blood pressure

The aim of this study was to test the effect of moderate dietary salt restriction on blood pressure and whether plasma renin would predict degree of salt sensitivity. Plasma renin concentration (P-renin) was measured in the upright position in 36 Swedish healthy subjects with normal or slightly elevated blood pressure when being on their habitual diet. The mean age was 53±10 years, 44% were male and systolic and diastolic blood pressure was 134±12 / 79±8 mmHg. During 8 weeks the subjects received all meals and drinks from our metabolic ward with a total daily NaCl content of 50 mmol. In addition, NaCl capslules (100 mmol/day) and corresponding placebo capsules were administered for 4 weeks each in random order (cross-over design). Office blood pressure (OBP), ambulatory blood pressure (ABP) and 24h urinary sodium excretion (tUNa) was measured at baseline and after the 4 weeks of high- (150 mmol/day) and low- (50 mmol/day) salt intake. Salt sensitivity was defined as the difference between 24-h ABP after the high- and low-salt periods. The tUNa after the low- and high-salt periods were 50±17 and 140±39 mmol (P