Diastolic blood pressure is related to urinary sodium excretion in hypertensive Chinese patients

Abstract

We studied 70 Hong Kong Chinese patients with untreated hypertension and 47 normotensive controls. Blood pressure measurements and 24-h urine collection were performed for each patient, and were repeated 12 weeks later in 14 hypertensive patients who remained untreated. Twenty-two hypertensive patients underwent ambulatory blood pressure monitoring. The primary hypothesis tested was a correlation between diastolic blood pressure and 24-h urinary sodium excretion. In the hypertensive patients, diastolic blood pressure correlated with 24-h urinary sodium excretion (r = 0.41, p < 0.001), even after adjustment for age, gender, body mass index, ethanol intake and season (r = 0.34, p = 0.02). In normotensive controls, diastolic blood pressure did not correlate with sodium excretion (r = 0.21, p = 0.16). A correlation between diastolic blood pressure and sodium excretion was also observed in the patients who underwent ambulatory blood pressure monitoring (r = 0.47, p = 0.026), and in repeat measurements in untreated patients (r = 0.60, p = 0.02). Systolic blood pressure did not correlate with sodium excretion, although it increased with patient age (0.6 ± 0.1 mmHg/year, p < 0.001). In a multiple regression analysis with diastolic blood pressure as the dependent variable, the regression coefficient was 0.06 ± 0.02 mmHg/mmol Na. The regression coefficients for ambulatory diastolic blood pressure and diastolic pressure repeated at 12 weeks were 0.07 ± 0.03 and 0.09 ± 0.04 mmHg/mmol Na, respectively. Urinary sodium excretion was related to diastolic blood pressure in our hypertensive patients, accounting for 17% of the variance of diastolic blood pressure.