Usefulness of self-monitoring of urinary salt excretion in hypertensive patients.

We investigated the usefulness of measuring urinary salt excretion by using a self-monitoring device. Subjects were 34 hypertensive patients who underwent successful 24-h home urine collection five times and 25 volunteers. Four volunteers were diagnosed as having hypertension based on home blood pressure (BP) readings. All subjects were asked to measure daily urinary salt excretion for 30 days by using a self-monitoring device which estimates 24-h salt excretion by overnight urine. The mean urinary salt excretion during the 30 days was 8.36 +/- 1.52 g/day and the range (maximum-minimum value) was 5.47 +/- 20.05 g/day in all subjects. Mean urinary salt excretion decreased from 8.52 +/- 1.63 g/day for the first 10 days to 8.31 +/- 1.54 g/day for the last 10 days (p < 0.05). The mean urinary salt excretion determined by a self-monitoring device using overnight urine was positively associated with that determined by 24-h home urine for five times in the hypertensive subjects (r = 0.63, p < 0.01). Results indicate that a self-monitoring device seems to be useful to monitor daily salt intake and to guide salt restriction.