SALT RESTRICTION IN HYPERTENSION - THE EFFECT OF DIETARY ADVICE AND SELF-MONITORING OF CHLORIDE CONCENTRATION IN URINE

The aims of this present study were firstly to examine whether diet co mpliance and blood pressure effect could be enhanced by self monitorin g with a titrator strip (Quantab 1176) measuring the urine chloride co ncentration. This was achieved by an open, randomized parallel group d esign. The study also sought to evaluate the blood pressure effect of a moderately salt restricted diet by using a pre-test-post-test design with a run-in period and controlling for relevant confounding factors (weight, training and alcohol consumption). Furthermore, the study ai ms were to validate the measurement of chloride concentration in the m orning urine by the Quantab titrator strip. We compared Quantab 1176 m easurement of chloride concentration in the morning urine with 24h sod ium excretion, determined by the clinical chemical laboratory, was per formed. Twenty men and 14 women (mean age 53 years) with essential hyp ertension (mean: 165/96 mmHg) were observed during a run-in period of 4 weeks before randomization to either dietary advice combined with se lf monitoring of morning urine chloride concentration for 12 weeks, or dietary advice alone. The reduction in diastolic blood pressure of 6 mmHg was not different in the two groups (between groups p = 0.44). Wi thin group changes of systolic blood pressure were 10 mmHg and 6 mmHg (p = 0.006 and p = 0.04) in the diet plus Quantab group, and the diet only group respectively (between groups p = 0.30). No significant diff erence in 24h sodium excretion could be detected between the groups. T he morning urine chloride concentration correlated moderately to the 2 4h urine sodium excretion (r = 0.66, p < 0.001). It is concluded that self monitoring was not effective either to enhance the salt restricti on diet compliance or the blood pressure effect in this study. A diast olic blood pressure reduction of 6 mmHg was attained by simple dietary advice.