Blood pressure and serum calcium responses to altered sodium intake in high renin hypertension.

Abstract

Subjects with high renin hypertension tend to be sodium-resistant showing paradoxical blood pressure responses to alterations in sodium intake. Of twenty-five subjects with high renin essential hypertension (ten females, 15 males, mean age 30 years), 14 were noted to have a decrease in mean arterial blood pressure (MAP) when sodium intake was increased from 10 to 100 mmol/d. The percentage response of plasma renin activity was greater in these patients than in those with an increase in MAP (-55.4 +/- 5.4 v -33.6 +/- 6.9, P = .018). Overall, the response of MAP was directly correlated to the percentage response of plasma renin activity (r = .549, P = .005), and inversely related to the change in serum calcium concentration (corrected for changes in serum albumin) (r = -.547, P = .005). No intercorrelation between the changes in plasma renin activity and serum calcium concentration was detected. The blood pressure response to increased sodium intake in high renin hypertension would appear to be divergent and related not only to the suppression of plasma renin activity, but also to changes in circulating calcium.