Self-monitoring of urinary salt excretion helps to improve 24 h urinary Na:K, salt check sheet scores and stage of eating behaviour. Thus, usage of self-monitoring tools has an educational potential in salt intake reduction.

The salt check sheet developed by Tsuchihashi et al. is widely used in general practice to assess salt intake and the associated diets. However, its appropriateness for the general population has not been assessed alongside 24-h urinary salt excretion monitoring. Therefore, in local residents, we analyzed the correlation between check-sheet scores and 24-h urinary salt excretion levels to determine the appropriateness of the check sheet. We asked 176 local residents to complete the salt check sheet and provide urinary samples; the latter were obtained using a proportional sampling method over a 24-h period. One hundred and forty subjects completed the study (men/women: 23/117, mean±s.d. age: 52.7±19.6 years, blood pressure: 122.3±18.0/74.3±11.1 mm Hg), of whom 51 (36.4%) had hypertension. The total salt check-sheet scores were widely distributed (mean±s.d.: 11.1±4.2 points, range: 0-22 points), and the subjects were divided into the following groups on the basis of salt levels: 29.3% were 'low' (0-8 points), 42.8% were 'medium' (9-13 points), 23.6% were 'high' (14-19 points) and 4.3% were 'very high' (>20 points). The mean 24-h urinary salt excretion level was 8.5±3.3 g. The subjects with higher salt-intake levels tended to have increased 24-h urinary salt excretion levels, with significant differences between the three groups ('low' vs. 'medium' vs. 'high to very high' salt levels: 7.6±2.9 g vs. 8.4±2.8 g vs. 9.6±4.2 g, respectively; P=0.03). The total salt check-sheet scores significantly correlated with the 24-h urinary salt excretion levels (r=0.27; P<0.01). Thus, the salt check sheet is applicable for the general population.

Self-measured salt excretion from overnight urine samples shows significant correlation with 24-h-urinary salt excretion, but it is not known whether a self-measuring method can monitor daily fluctuations in individual salt consumption. In this study, we measured salt excretion from 24-h urine samples (24-h salt) in 50 volunteers over 3 test days (2 weekdays and 1 holiday), and examined to what extent the values correlated with estimates of 24-h salt excretion from overnight urine samples obtained using a self-monitoring device (ON salt). Urine collection was considered successful when the difference between the predicted and actual 24-h-urinary creatinine excretion was within 30%. Thirty-three (M/F=7/26; 39.6±16.7 years) out of 50 participants completed their urine collections successfully and their samples were used in the analysis. Twenty-four-hour salt and ON salt did not significantly differ between test days and between the weekdays and the holiday. Moreover, there was a significant positive correlation between 24-h salt and ON salt for each test day. The coefficients of variation (CVs) for 24-h salt among test days and among subjects were 24.7% and 21.3%, respectively. The CVs for ON salt were lower than those for 24-h salt (13.3% and 17.7%, respectively). In conclusion, self-measurement of salt excretion from overnight urine samples allows estimation of daily salt intake; thus, the use of a self-monitoring device may be a useful motivational tool for personal salt restriction.

The authors investigated interannual differences in the sodium excretion levels of young healthy Japanese women as estimated from spot urine analysis at Nakamura Gakuen University from 1995 to 2015. Participants included 4931 women aged 18 to 20 years who were classified into three time periods according to year of health check:first (1995-2001), second (2002-2007), and third (2008-2015). Estimated daily urinary sodium and potassium excretion levels and the sodium to potassium ratio were 120.6±31.9 mmol, 35.2±8.1 mmol, and 3.5±0.9, respectively. Adjusted for body weight, sodium excretion, and potassium excretion significantly decreased in the second and third period compared with the first period (P<.001). Systolic blood pressure also decreased in the same way between time periods (P<.001). Estimated urinary excretion levels of sodium and potassium in young Japanese women have decreased over the past 20 years independently of body weight. | INTRODUCTIONExcess sodium intake plays an important role in the development and progression of hypertension and the development of cardiovascular diseases.1-3 It has been reported that excess sodium intake from early stages of life contributes to population increases in blood pressure (BP), hypertension, and prehypertension. 4 Estimations of the mortality rates resulting from reductions in salt intake as a function of age suggest a greater attenuation of mortality rates for younger people. 5These reports suggest that reducing salt intake from a younger age is an important lifestyle modification when it comes to prophylactic and therapeutic issues of hypertension. Large-scale trends in sodium intake during recent decades have not yet been reported for young Japanese people. The Japanese National Health and Nutrition Survey provides information on interannual changes in the sodium intake of Japanese people. According to this survey, the sodium intake of young people has decreased during the past 20 years, but sodium intake corrected for energy intake was relatively unchanged during the past 10 years. 6,7 However, this survey has several limitations. For instance, the proportion of young people in the population surveyed was small, and sodium intake was calculated as a function of food consumed by a family and position in the family (eg, 35% intake for the father, 25%intake for the mother, and 40% intake for two children), 8 and thus the investigation underestimates the actual amount of diet. 9,10 Notably, the results of a salt intake study of 760 Japanese people aged 20 to 69 years with 24-hour urinary sodium excretion measurements taken at two time points differ from Japanese National Health and Nutrition Survey results, raising the question of whether salt intake did decline across these decades. 8 To better determine recent trends in the sodium intake of Japanese people, we need to evaluate changes in urinary sodium excretion levels and compare these values with the sodium intakes recorded by the Japanese National Health and Nutrition

In this study, the authors measured sodium and potassium concentrations in spot urine samples of preschool children on multiple days, and evaluated individual, daily, and seasonal effects. A total of 104 healthy preschool children aged 4 to 5 years were studied. Urine samples were collected from the first urine of the day after waking for three consecutive days (Monday-Wednesday) four times a year (spring, summer, autumn, winter). The authors estimated the daily urine volume as 500 mL and daily creatinine excretion as 300 mg, and used these to calculate daily sodium and potassium excretion levels. Daily sodium and potassium excretion levels and sodium to potassium ratios were highly variable. The coefficient variant in the children's excretion levels were also high within and between individuals. Sodium excretion levels and sodium to potassium ratios were higher on Monday (weekend sodium intakes) than Tuesday. Season had no effect on sodium or potassium excretion levels, but the sodium to potassium ratio was higher in summer than in winter. In conclusion, levels of urinary sodium excretion are comparatively high and those of potassium are low in preschool students, with high variability within and between individuals.