Evaluation of three prediction formulas of 24-hour urinary sodium excretion in Chinese residents: a systematic review and meta-analysis.

OBJECTIVE: To determine the appropriateness of three widely used formulas estimating 24-h urinary Na (24hUNa) from spot urine samples in the Chinese population. DESIGN: Systematic review and meta-analysis. SETTING: Literature review was conducted to identify studies for estimating 24hUNa using the Kawasaki, Tanaka and INTERSALT formulas simultaneously in PubMed, Embase and the Cochrane library databases. The mean difference (MD) and correlation coefficients (r) between measures and estimates from different formulas were assessed. PARTICIPANTS: Information extraction and quality assessment were performed in thirteen studies involving 8369 subjects. RESULTS: Two studies which affected the overall robustness were excluded in the 'leave-one-out' sensitivity analyses. Within the final meta-analysis included eleven studies and 7197 participants, 36·07 mmol/d (95 %CI 16·89, 55·25) of MD was observed in the Kawasaki formula, and -19·62 mmol/d (95 %CI -37·37, -1·87) in the Tanaka formula and -35·78 mmol/d (95 %CI -50·76, -20·80) in the INTERSALT formula; a pooled r-Fisher's Z of 0·39 (95 %CI 0·32, 0·45) in the Kawasaki formula, 0·43 (95 %CI 0·37, 0·49) in the Tanaka formula and 0·36 (95 %CI 0·31, 0·42) in the INTERSALT formula. Subgroup analyses were conducted to explore the possible factors affecting the accuracy of the formula estimation from three mainly aspects: population types, Na intake levels and urine specimen types. CONCLUSIONS: The meta-analysis suggested that the Tanaka formula performed a more accurate estimate in Chinese population. Time of collecting spot urine specimens and Na intake level of the sample population might be the main factors affecting the accuracy of the formula estimation.

No change in 24-h sodium intake estimated from spot urine in Norwegian adults from 2006 to 2019: the population-based Trøndelag Health Study (HUNT).

OBJECTIVE: Monitoring time trends in salt consumption is important for evaluating the impact of salt reduction initiatives on public health outcomes. There has so far not been available data to indicate if salt consumption in Norway has changed during the previous decade. We aimed to assess whether average 24-h salt intake estimated from spot urine samples in the adult population of mid-Norway changed from 2006-2008 to 2017-2019 and to describe variations by sex, age and educational level. DESIGN: Repeated cross-sectional studies. SETTING: The population-based Trøndelag Health Study (HUNT). PARTICIPANTS: In each of two consecutive waves (HUNT3: 2006-2008 and HUNT4: 2017-2019), spot urine samples were collected from 500 men and women aged 25-64 years, in addition to 250 men and women aged 70-79 years in HUNT4. Based on spot urine concentrations of Na, K and creatinine and age, sex and BMI, we estimated 24-h Na intake using the International Cooperative Study on Salt and Blood Pressure (INTERSALT) equation for the Northern European region. RESULTS: Mean (95 % CI) estimated 24-h salt intakes in men were 11·1 (95 % CI 10·8, 11·3) g in HUNT3 and 10·9 (95 % CI 10·6, 11·1) g in HUNT4, P = 0·25. Corresponding values in women were 7·7 (95 % CI 7·5, 7·9) g and 7·7 (95 % CI 7·5, 7·9) g, P = 0·88. Mean estimated salt intake in HUNT4 decreased with increasing age in women, but not in men, and it did not differ significantly across educational level in either sex. CONCLUSIONS: Estimated 24-h salt intake in adult men and women in mid-Norway did not change from 2006-2008 to 2017-2019.

Twenty-four hour urinary sodium and potassium excretion in adult population of Slovenia: results of the Manjsoli.si/2022 study.

OBJECTIVE: The objective of study was to assess 24-h urinary Na and K excretion and estimate the average salt and K intakes in a nationally representative sample of the adult population of Slovenia. DESIGN: A nationally representative cross-sectional study was conducted in four stages between September and November 2022: study questionnaire, physical measurements, 24-h urine collection and laboratory analysis. SETTING: Slovenia. PARTICIPANTS: We invited 2000 adult, non-institutionalised inhabitants of Slovenia, aged between 25 and 64 years. A stratified two-staged sample was selected from this population by the Statistical Office of Slovenia, using sampling from the Central Population Register. According to the WHO methodology, additional eligibility criteria were screened before participating. A total of 518 individuals participated in all four stages of the study, resulting in a response rate of 30 %. RESULTS: The mean 24-h urinary Na excretion was 168 mmol/d (95 % CI 156, 180), which corresponds to a mean estimated intake of 10·3 g salt/d (95 % CI 9·6, 11·1). Mean 24-h urinary K excretion was 65·4 mmol/d (95 % CI 63·2, 67·5), and the estimated mean K intake was 2·93 g/d (95 % CI 2·84, 3·03). There were statistically significant differences in mean intakes between males and females. The mean sodium-to-potassium ratio was 2·7 (95 % CI 2·5, 2·8). CONCLUSIONS: The study results highlighted that the salt intake in the adult population of Slovenia remains much higher than recommended by the WHO, and K intakes are insufficient, as most participants did not meet the recommendations.

Validation of spot urine in estimating 24-h urinary sodium, potassium and sodium-to-potassium ratio during three different sodium diets in healthy adults.

PURPOSE: To evaluate the validity of spot urine assay methods in estimating the 24-h urinary sodium, potassium and sodium-to-potassium ratio during three different sodium diets. MATERIALS AND METHODS: Twelve healthy volunteers were asked to adhere to 3 dietary sodium targets (3.3-5.0g/day,<3.3 g/day and >5.0 g/day) for three consecutive weeks and to measure salt excretion daily in spot urine samples using a self-monitoring device. On day 7 of each week, 24-h urine was collected to compare measured with estimated 24-h salt excretion (by the Kawasaki, Tanaka and INTERSALT equations). RESULTS: Correlation coefficients relating measured and estimated 24-h sodium excretion were low and not significant for Kawasaki and INTERSALT and moderate for the Tanaka equation (τ 0.56-0.64,p<.05). Bland-Altman plots showed considerable differences between estimated and measured sodium excretion across all salt diets. Over 40% of the participants showed an absolute difference between measured and estimated 24-h sodium of more than 1000 mg/day. The correlation coefficients between 24-h and spot Na/K ratio were 0.67, 0.94 and 0.85(p<.05), and mean differences were 0.59, 0.06 and 0.48 for the intermediate, low and high sodium diets, respectively. CONCLUSION: These findings do not support estimation of individual 24-h salt excretion from spot urine by the Kawasaki, Tanaka, or INTERSALT formula. Plain language summaryAccurate monitoring of salt intake is essential to improve BP control. At present, measurement of sodium and potassium excretion in multiple non-consecutive 24-h urinary collections is considered the gold standard for measuring dietary sodium intake. However, this method is burdensome, time-consuming and error prone.Therefore, we assessed and compared the validity of three formula-based approaches to estimate 24-h urinary sodium and potassium excretion and the Na/K ratio from spot urine samples measured by a self-monitoring device under three different sodium diets using 24-h urine collections as the reference.We conclude that use of three commonly used equations that estimate 24-h urinary sodium and potassium excretion result in substantial bias, poor precision and poor accuracy and are therefore not recommended. The Na/K ratio based on multiple casual urine samples may be a useful, low-burden, low-cost alternative method to 24-h urine collection for monitoring daily salt intake.

Salt intake and blood pressure in Iranian children and adolescents: a population-based study.

BACKGROUND: Previous studies have reported a high prevalence of hypertension in Iranian students, especially in rural areas. The aim of this study was to investigate the daily intake of salt in students and its association with high blood pressure. METHODS: A random sub-sample was selected from the participants of the second phase of Shahroud schoolchildren eye cohort study and then a random urine sample was tested for sodium, potassium and creatinine. Urine electrolyte esexcretion and daily salt intake were calculated by Tanaka et al.'s formula. RESULTS: Among 1455 participants (including 230 participants from rural area and 472 girls), the mean age was 12.9 ± 1.7 year and the mean daily salt intake was 9.7 ± 2.6 g (95% CI 9.5-9.8). The mean salt consumption in rural areas [10.8 (95% CI 10.4-11.2)] was higher than urban areas [9.4 (95% CI 9.3-9.6)], in people with hypertension [10.8 (95% CI 10.3-11.3)] was more than people with normal blood pressure [9.4 (95% CI 9.3-9.6)], and in boys [9.8 (95% CI 9.7-10.0)] was more than girls [9.3 (95% CI 9.1-9.6)]. Higher age, BMI z-score, male sex and rural life, were associated with increased daily salt intake. Increased salt intake was associated with increased systolic and diastolic blood pressure. CONCLUSION: Daily salt intake in Iranian adolescents was about 2 times the recommended amount of the World Health Organization, was higher in rural areas and was associated with blood pressure. Reducing salt intake should be considered as an important intervention, especially in rural areas.

Trend in potassium intake and Na/K ratio in the Italian adult population between the 2008 and 2018 CUORE project surveys.

BACKGROUND AND AIMS: Low potassium intake, in addition to high sodium, has been associated with higher risk of hypertension and CVD. The Study assessed habitual potassium intake and sodium/potassium ratio of the Italian adult population from 2008 to 2012 to 2018-2019 based on 24-h urine collection, in the framework of the CUORE Project/MINISAL-GIRCSI/MENO SALE PIU' SALUTE national surveys. METHODS AND RESULTS: Data were from cross-sectional surveys of randomly selected age-and-sex stratified samples of resident persons aged 35-74 years in 10 (out of 20) Italian regions. Urinary electrolyte and creatinine measurements were performed in a central laboratory. Analyses considered 942 men and 916 women, examined in 2008-2012, and 967 men and 1010 women, examined in 2018-2019. In 2008-2012, the age-standardized mean of potassium intake (urinary potassium accounts for 70% of potassium intake) was 3147 mg (95% CI 3086-3208) in men and 2784 mg (2727-2841) in women, whereas in 2018-2019, it was 3043 mg (2968-3118) and 2561 mg (2508-2614) respectively. In 2008-2012, age-adjusted prevalence of persons with an adequate potassium intake (i.e. ≥ 3510 mg/day) was 31% (95% CI 28-34%) for men and 18% (16-21%) for women; in 2018-2019, it was 26% (23-29%) and 12% (10-14%) respectively. The sodium/potassium ratio significantly decreased both in men and women. CONCLUSIONS: The average daily potassium intake of the Italian general adult population remains lower than the WHO and EFSA recommended level. These results suggest the need of a revision to strengthen initiatives for the promotion of an adequate potassium intake at the population level.

The effect of uric acid and urinary sodium excretion on prehypertension: a nationwide population-based study.

BACKGROUND: This study examined the effect of serum uric acid (SUA) level and urinary sodium excretion on blood pressure as well as their combined effect on prehypertension in a Korean population. METHOD: Data from the 7th Korea National Health and Nutrition Examination Survey for adults (≥ 19 years of age) were used. The participants were classified into two groups, normotension and prehypertension, according to the JNC-7 definition. Logistic regression was carried out and adjusted for traditionally regarded confounders of blood pressure. All analyses considered a complex sampling design. A multivariate analysis was performed on subgroups defined according to their SUA level and urinary sodium excretion. RESULTS: The 4200 participants were divided into normotension (n = 2646) and prehypertension (n = 1554) groups. In the univariate analysis, patient age, male sex, concurrent comorbidity (diabetes mellitus, cardiovascular disease, stroke, dyslipidemia, and chronic kidney disease), uric acid, and urinary sodium excretion were associated with prehypertension. After adjusting for baseline covariates, both the SUA level and urinary sodium excretion were significant predictors of incident prehypertension (SUA, per 1 mg/dL increase, odds ratio [OR] 1.216, 95% confidence interval [95% CI] 1.131-1.309; urinary sodium excretion, per 1 g/day increase, OR 1.067, 95% CI 1.019-1.117). Additionally, simultaneously higher tertiles of SUA and urinary sodium excretion resulted in higher ORs for prehypertension. CONCLUSION: Increased SUA is a significant risk marker for the development of prehypertension in normotensives. Simultaneously high SUA and urinary sodium excretion amplified the effect on the development of prehypertension. Our findings suggest that lowering SUA levels and reducing sodium intake will contribute to preventing hypertension.

Can methods based on spot urine samples be used to estimate average population 24 h sodium excretion? Results from the Isfahan Salt Study.

OBJECTIVE: To assess agreement between established methods of estimating salt intake from spot urine collections and 24 h urinary Na (24hUNa) and then to develop a valid formula that can be used in the Iranian population to estimate salt intake from spot urine samples. DESIGN: A validation study. Three spot urine samples were collected (fasting second-void morning; afternoon; evening) on the same day as a 24 h urine collection. We estimated 24hUNa from spot specimens using the Kawasaki, Tanaka and INTERSALT equations. Two new formulas were developed, the Iran formula 1 (Iran 1) and Iran formula 2 (Iran 2), based on our population characteristics. SETTING: Iranian adults recruited in 2014-2015. PARTICIPANTS: Healthy volunteer adults aged ≥18 years. RESULTS: With all three spot urine specimens, predicted population 24hUNa was underestimated based on the INTERSALT equation (-469 to -708 mg/d; all P < 0·05) and conversely overestimation occurred with the Kawasaki equation (926 to 1080 mg/d; all P < 0·01). The Tanaka equation produced comparable estimates to measured 24hUNa (-151 to 86 mg/d; all P > 0·49). The newly derived formulas, Iran 1 and Iran 2, showed less mean bias than the established equations (Iran 1: 43 to 80 mg/d, all P > 0·55; Iran 2: 22 to 90 mg/d, all P > 0·50). CONCLUSIONS: In this Iranian sample, the Tanaka equation and newly derived formulas produced group-level estimates comparable to measured 24hUNa. The newly developed formulas showed less mean bias than established equations; however, they need to be tested for generalization in a larger sample.

Insight Into Differences in Dietary Sodium Adherence Between Men and Women With Heart Failure.

BACKGROUND: Men with heart failure are reported to be less adherent to low-sodium diets than women are. One potential reason may be that men consume more food and, consequently, more sodium than women do. OBJECTIVES: The aims of this study were to compare dietary sodium intake, urine sodium excretion, and sodium density of diet consumed between men and women with heart failure and to determine whether sex moderated the relationship of kilocalories (kcals) consumed with dietary and urine sodium. METHODS: A total of 223 patients with heart failure (mean age, 62 ± 12 years; 70% men, 46% New York Heart Association class III-IV) completed detailed 4-day food diaries and provided 24-hour urine sodium samples. To account for sodium density of food, dietary sodium and urine sodium were referenced to sodium per 1000 kcal. RESULTS: On an absolute basis, men consumed 23% more kcals and 28% more sodium than women did; 24-hour sodium excretion was 16% higher in men than in women. There were no differences between men and women when dietary sodium and urinary sodium were referenced to 1000 kcal, indicating they consumed foods with similar sodium density. However, both moderation analyses showed that the dietary sodium intake of men and women with lower kcal intake was similar, whereas men with higher kcal intake consumed more sodium-dense foods than women did. CONCLUSION: The results suggest that the men with higher sodium intake than women had 2 reasons for nonadherence. They consumed more food and foods with higher sodium density than women did.

The association of blood pressure with estimated urinary sodium, potassium excretion and their ratio in hypertensive, normotensive, and hypotensive Chinese adults.

BACKGROUND AND OBJECTIVES: Low sodium and high potassium intake is reported to be a risk of hypertension. However, it is uncertain whether these associations can be generalized to those without hypertension. This study is to evaluate the associations of systolic and diastolic blood pressure (SBP and DBP, respectively) with estimated urinary sodium excretion (eUNaE), estimated urinary potassium excretion (eUKE) and their ratio (Na/K ratio) among hypertensive, normotensive, and hypotensive Chinese individuals. METHODS AND STUDY DESIGN: A large institution-based cross-sectional study was conducted at the Third Xiangya Hospital, Changsha between August 2017 and November 2018. Spot urine samples were collected to test urinary sodium, potassium, and creatinine excretions for each participant. The Kawasaki formula was used to estimate 24-hour urinary sodium and potassium excretions. RESULTS: A total of 26,363 eligible subjects were used to analyze the associations of blood pressure with eUNaE, eUKE, and their ratio. 27.3% (n=7,201) of participants were diagnosed with hypertension, 5.4% (n=1,427) were diagnosed with hypotension, and the remaining of 17,735 participants were normotensive. A significant increase in SBP and DBP was related to the Na/K ratio increase in hypertensive and normotensive subgroups (all ptrend<0.01), but the association was not significant for DBP among hypotensive individuals (ptrend=0.58). Stronger associations of SBP with the Na/K ratio were observed in older people (pinteraction<0.01) and females (pinteraction<0.0001), but the same trend was not observed for DBP (pinteraction=0.10 and 0.88, respectively). CONCLUSIONS: High potassium and low sodium intake were further confirmed to reduce blood pressure in hypotensive, normotensive, and hypertensive individuals.

Trend of salt intake measured by 24-hour urine collection samples among Iranian adults population between 1998 and 2013: The Isfahan salt study.

BACKGROUND AND AIM: Few population-based studies conducted in the Eastern Mediterranean region assessed salt intake by the measurement of 24-h sodium urine excretion (24-hUNa). The current study aimed to assess the trend of mean salt intake in Iranian adults between 1998 and 2013. METHODS AND RESULTS: These cross-sectional studies were performed on 564, 157, 509 and 837 randomly selected healthy adults aged >18 years from Isfahan city, Iran, in 1998, 2001, 2007 and 2013, respectively. BP was measured using a mercury sphygmomanometer according to a standard protocol. Single 24-h urine was collected to assess 24-hUNa as a surrogate of salt intake, and 24-h urinary K (24-hUK). The estimated trend of salt intake was 9.5, 9.7, 9.6 and 10.2 g/day in total population (P < 0.001). The increase in salt intake between 1998 and 2013 was significant only in men, (P < 0.001). The risk of pre-hypertension was 21% and 18% significantly greater in the highest quartiles of UNa/UK after adjustment for potential confounders in 2001 and 2013, respectively, [OR (95% CI): 1.21 (1.03-1.64) and 1.18 (1.02-1.38), respectively]. CONCLUSIONS: This population-based study indicated that mean salt intake was about two times of recommendation in Isfahan city, Iran, and suggest that it would be essential to implement a salt reduction strategy program in Iranian population. Longitudinal national studies with larger samples examining the trend of salt intake are warranted.

Soluble endothelial protein C is associated with blood pressure variability and salt consumption but not mean blood pressure in patients with newly diagnosed primary hypertension.

BACKGROUND: Hypertension is a widespread disease involving frequent thrombotic complications. Blood pressure variability (BPV) has recently been shown to be associated with end-organ damage and cardiovascular events. However, the pathogenesis of the relation between BPV and cardiovascular events has not yet been explained. Soluble endothelial protein C (sEPCR) exhibits a procoagulant effect by reducing the anticoagulant and anti-inflammatory effects of protein C and activated protein C. The purpose of this study was to evaluate sEPCR levels in hypertensive individuals and the parameters affecting that level, particularly BPV. METHODS: Fifty-one newly diagnosed hypertensive subjects and 31 healthy individuals were included in the study. Twenty-four-hour ambulatory blood pressure monitoring (ABPM) was performed after office control, and simultaneous 24-h urine was collected. BPV was calculated with average real variability (ARV) from ABPM data. Blood specimens were collected under appropriate conditions for sEPCR levels and biochemical tests. sEPCR levels were compared between the patient and healthy groups, after which parameters affecting sEPCR elevation in the hypertensive group were evaluated. RESULTS: sEPCR levels were significantly high in the hypertensive group (p < 0.05). At multivariate regression analysis in the hypertensive group, sEPCR was determined to be independently associated with 24-h systolic ARV (ß = 0.572, p < 0.05) and 24-h urine Na (ß = 0.428, p < 0.05). CONCLUSION: In our study, sEPCR was high in hypertensive individuals, and this elevation was related to ARV and urine Na excretion independently of mean blood pressure.

Dietary Sodium Reduction Reduces Albuminuria: A Cluster Randomized Trial.

OBJECTIVES: The objective of the study was to assess the impact of sustained dietary salt reduction on albuminuria in nearly 2000 community-dwelling adults. DESIGN AND METHODS: The present study is a prespecified secondary analysis of the China Rural Health Initiative Salt Reduction Study cluster randomized trial undertaken in 120 villages in rural China. Villages were randomized to a sodium reduction program of education and access to reduced-sodium salt substitute or control. Urinary albumin-to-creatinine ratio (uACR) and albuminuria (uACR ≥22.1 or 31.0 mg/g for men and women, respectively) were assessed at 18 months in a stratified random sample of predominantly older individuals living in participating rural villages. RESULTS: A total of 2,566 participants from 119 villages provided 1,903 eligible urine samples. The sodium reduction program reduced sodium intake by an equivalent of 0.82g of salt/day (0.06-1.68 g) (322 [24-661] mg sodium/day). The mean uACR was 8.85 (8.05-9.82) mg/g (1.00 [0.91-1.11] mg/mmol) in intervention participants compared with 10.53 (9.73-11.33) mg/g (1.19 [1.10-1.28] mg/mmol) in control participants (p=0.008). The corresponding odds ratio for albuminuria was 0.67 (0.46-0.99). CONCLUSIONS: Dietary sodium reduction was associated with significantly lower uACR and less albuminuria after 18 months. Whether CKD progression can be slowed by dietary sodium reduction should be a global research priority. CLINICALTRIALS.GOV: NCT01259700.

Neuronal (pro)renin receptor regulates deoxycorticosterone-induced sodium intake.

Increased sodium appetite is a physiological response to sodium deficiency; however, it has also been implicated in disease conditions such as congestive heart failure, kidney failure, and salt-sensitive hypertension. The central nervous system is the major regulator of sodium appetite and intake behavior; however, the neural mechanisms underlying this behavior remain incompletely understood. Here, we investigated the involvement of the (pro)renin receptor (PRR), a component of the brain renin-angiotensin system, in the regulation of sodium intake in a neuron-specific PRR knockout (PRRKO) mouse model generated previously in our laboratory. Sodium intake following deoxycorticosterone (DOCA) stimulation was tested by assessing the preference of mice for 0.9% saline or regular water in single-animal metabolic cages. Blood pressure was monitored in conscious, freely moving mice by a telemetry system. We found that saline intake and total fluid intake were significantly reduced in PRRKO mice following DOCA treatment compared with that in wild-type (WT) mice, whereas regular water intake was similar between the genotypes. Sodium preference and total sodium intake were significantly reduced in PRRKO mice compared with WT mice. PRRKO mice also excreted less urine and urinary sodium compared with WT mice following DOCA treatment, whereas potassium excretion was similar between the two groups. Finally, we found that the sodium balance, calculated by subtracting urinary sodium excretion from sodium intake, was greater in WT mice than in PRRKO mice. Collectively, these findings suggest that the neuronal PRR plays a regulatory role in DOCA-induced sodium intake.

Sodium intake and multiple sclerosis activity and progression in BENEFIT.

OBJECTIVE: To assess whether a high-salt diet, as measured by urinary sodium concentration, is associated with faster conversion from clinically isolated syndrome (CIS) to multiple sclerosis (MS) and MS activity and disability. METHODS: BENEFIT was a randomized clinical trial comparing early versus delayed interferon beta-1b treatment in 465 patients with a CIS. Each patient provided a median of 14 (interquartile range = 13-16) spot urine samples throughout the 5-year follow-up. We estimated 24-hour urine sodium excretion level at each time point using the Tanaka equations, and assessed whether sodium levels estimated from the cumulative average of the repeated measures were associated with clinical (conversion to MS, Expanded Disability Status Scale [EDSS]) and magnetic resonance imaging (MRI) outcomes. RESULTS: Average 24-hour urine sodium levels were not associated with conversion to clinically definite MS over the 5-year follow-up (hazard ratio [HR] = 0.91, 95% confidence interval [CI] = 0.67-1.24 per 1g increase in estimated daily sodium intake), nor were they associated with clinical or MRI outcomes (new active lesions after 6 months: HR = 1.05, 95% CI = 0.97-1.13; relative change in T2 lesion volume: -0.11, 95% CI = -0.25 to 0.04; change in EDSS: -0.01, 95% CI = -0.09 to 0.08; relapse rate: HR = 0.78, 95% CI = 0.56-1.07). Results were similar in categorical analyses using quintiles. INTERPRETATION: Our results, based on multiple assessments of urine sodium excretion over 5 years and standardized clinical and MRI follow-up, suggest that salt intake does not influence MS disease course or activity. Ann Neurol 2017;82:20-29.

The relationship between habitual dietary sodium intake and RAAS blockade on circulating microparticle levels in type two diabetes.

OBJECTIVE: Low sodium intake is paradoxically associated with adverse cardiovascular outcomes in individuals with type 2 diabetes mellitus (T2D), possibly from renin-angiotensin-aldosterone system (RAAS) activation, leading to endothelial dysfunction. In the present study, we investigated the associations between habitual sodium intake and RAAS blockade on endothelial function by measuring circulating microparticles (MPs) in individuals with T2D. METHODS: We conducted a prospective, cross-sectional study in 74 individuals with T2D. Habitual dietary sodium intake was estimated by using the mean of three corrected 24-h urine sodium excretion measurements (24hUNa). MP subtypes in platelet-free plasma were quantitated using flow cytometry. RESULTS: No associations between 24hUNa with levels of endothelial MPs were observed. Instead, a trend toward higher diabetes related CD36+/CD235a+ MP levels was associated with lower 24hUNa (rho = -0.23, P=0.05). When stratified according to tertiles of 24hUNa, platelet-derived CD42b+/CD41+ and CD42+/CD41+/Annexin V+ MPs were higher in the lowest tertile (24hUNa < 157 mmol/24 h) (P=0.02 respectively). Despite RAAS blockade being associated with lower levels of most MP subsets, it was not associated with lower MPs, in the setting of low sodium intake. CONCLUSION: Lower sodium intake is associated with higher circulating procoagulant MPs, but not with evidence of endothelial dysfunction in individuals with T2D.

Microvascular Permeability after an Acute and Chronic Salt Load in Healthy Subjects: A Randomized Open-label Crossover Intervention Study.

BACKGROUND: Sodium-induced microcirculatory changes, endothelial surface layer alterations in particular, may play an important role in sodium-mediated blood pressure elevation. However, effects of acute and chronic sodium loading on the endothelial surface layer and microcirculation in humans have not been established. The objective of this study was to assess sodium-induced changes in blood pressure and body weight as primary outcomes and also in microvascular permeability, sublingual microcirculatory dimensions, and urinary glycosaminoglycan excretion in healthy subjects. METHODS: Twelve normotensive males followed both a low-sodium diet (less than 50 mmol/day) and a high-sodium diet (more than 200 mmol/day) for eight days in randomized order, separated by a crossover period. After the low-sodium diet, hypertonic saline (5 mmol sodium/liter body water) was administered intravenously in 30 min. RESULTS: Both sodium interventions did not change blood pressure. Body weight increased with 2.5 (95% CI, 1.7 to 3.2) kg (P < 0.001) after dietary sodium loading. Acute intravenous sodium loading resulted in increased transcapillary escape rate of I-labeled albumin (2.7 [0.1 to 5.3] % cpm · g · h; P = 0.04), whereas chronic dietary sodium loading did not affect transcapillary escape rate of I-labeled albumin (-0.03 [-3.3 to 3.2] % cpm · g · h; P = 1.00), despite similar increases of plasma sodium and osmolality. Acute intravenous sodium loading coincided with significantly increased plasma volume, as assessed by the distribution volume of albumin, and significantly decreased urinary excretion of heparan sulfate and chondroitin sulfate. These changes were not observed after dietary sodium loading. CONCLUSIONS: Our results suggest that intravenous sodium loading has direct adverse effects on the endothelial surface layer, independent of blood pressure.

Socioeconomic Status Associated With Urinary Sodium and Potassium Excretion in Japan: NIPPON DATA2010.

BACKGROUND: Although socioeconomic status (SES) may affect food and nutrient intakes, few studies have reported on sodium (Na) and potassium (K) intakes among individuals with various SESs in Japan. We investigated associations of SES with Na and K intake levels using urinary specimens in a representative Japanese population. METHODS: This was a cross-sectional study of 2,560 men and women (the NIPPON DATA2010 cohort) who participated in the National Health and Nutrition Survey Japan in 2010. Casual urine was used to calculate estimated excretion in 24-hour urinary Na (E24hr-Na) and K (E24hr-K). The urinary sodium-to-potassium (Na/K) ratio was calculated from casual urinary electrolyte values. An analysis of covariance was performed to investigate associations of aspects of SES, including equivalent household expenditure (EHE), educational attainment, and job category, with E24hr-Na, E24hr-K, and the Na/K ratio for men and women separately. A stratified analysis was performed on educational attainment and the job category for younger (<65 years) and older (≥65 years) participants. RESULTS: In men and women, average E24hr-Na was 176.2 mmol/day and 172.3, average E24hr-K was 42.5 and 41.3, and the average Na/K ratio was 3.61 and 3.68, respectively. Lower EHE was associated with a higher Na/K ratio in women and lower E24hr-K in men and women. A shorter education was associated with a higher Na/K ratio in women and younger men, and lower E24hr-K in older men and women. CONCLUSION: Lower EHE and a shorter education were associated with a lower K intake and higher Na/K ratio estimated from casual urine specimens in Japanese men and women.

Effectiveness of a Self-monitoring Device for Urinary Sodium-to-Potassium Ratio on Dietary Improvement in Free-Living Adults: a Randomized Controlled Trial.

BACKGROUND: Reducing the urinary sodium-to-potassium ratio is important for reducing both blood pressure and risk of cardiovascular disease. Among free-living Japanese individuals, we carried out a randomized trial to clarify the effect of lifestyle modification for lowering urinary sodium-to-potassium ratio using a self-monitoring device. METHODS: This was an open, prospective, parallel randomized, controlled trial. Ninety-two individuals were recruited from Japanese volunteers. Participants were randomly allocated into intervention and control groups. A month-long dietary intervention on self-monitoring urinary sodium-to-potassium ratio was carried out using monitors (HEU-001F, OMRON Healthcare Co., Ltd., Kyoto, Japan). All participants had brief dietary education and received a leaflet as usual care. Monitors were handed out to the intervention group, but not to the control group. The intervention group was asked to measure at least one spot urine sodium-to-potassium ratio daily, and advised to lower their sodium-to-potassium ratio toward the target of less than 1. Outcomes included changes in 24-hour urinary sodium-to-potassium ratio, sodium excretion, potassium excretion, blood pressure, and body weight in both groups. RESULTS: Mean measurement frequency of monitoring was 2.8 times/day during the intervention. Changes in urinary sodium-to-potassium ratio were -0.55 in the intervention group and -0.06 in the control group (P = 0.088); respective sodium excretion changes were -18.5 mmol/24 hours and -8.7 mmol/24 hours (P = 0.528); and corresponding potassium excretion was 2.6 mmol/24 hours and -1.5 mmol/24 hours (P = 0.300). No significant reductions were observed in either blood pressure or body weight after the intervention. CONCLUSIONS: Providing the device to self-monitor a sodium-to-potassium ratio did not achieve the targeted reduction of the ratio in "pure self-management" settings, indicating further needs to study an effective method to enhance the synergetic effect of dietary programs and self-monitoring practice to achieve the reduction. However, we cannot deny the possibility of reducing sodium-to-potassium ratio using a self-monitoring device.

The relationship of health/food literacy and salt awareness to daily sodium and potassium intake among a workplace population in Switzerland.

BACKGROUND AND AIMS: High sodium (Na) and low potassium (K) intake are associated with hypertension and CVD risk. This study explored the associations of health literacy (HL), food literacy (FL), and salt awareness with salt intake, K intake, and Na/K ratio in a workplace intervention trial in Switzerland. METHODS AND RESULTS: The study acquired baseline data from 141 individuals, mean age 44.6 years. Na and K intake were estimated from a single 24-h urine collection. We applied validated instruments to assess HL and FL, and salt awareness. Multiple linear regression was used to investigate the association of explanatory variables with salt intake, K intake, and Na/K. Mean daily salt intake was 8.9 g, K 3.1 g, and Na/K 1.18. Salt intake was associated with sex (p < 0.001), and K intake with sex (p < 0.001), age (p = 0.02), and waist-to-height ratio (p = 0.03), as was Na/K. HL index and FL score were not significantly associated with salt or K intake but the awareness variable "salt content impacts food/menu choice" was associated with salt intake (p = 0.005). CONCLUSION: To achieve the established targets for population Na and K intake, health-related knowledge, abilities, and skills related to Na/salt and K intake need to be promoted through combined educational and structural interventions. Clinical Trials Registry number: DRKS00006790 (23/09/2014).