24-h Urinary Sodium Excretion Research Articles

Salt intake, blood pressure and cardiovascular disease mortality in England, 2003-2018.

The aim of this study was to assess the changes in salt intake and concomitant changes in blood pressure (BP) and cardiovascular disease (CVD) mortality in England from 2003 to 2018. National surveys and death registration data were used for the analysis of salt intake as measured by 24-h urinary sodium excretion (449-1069 participants per year), BP (2651-6738 participants per year) and CVD mortality. A decline in salt intake from 9.38 (SD 4.64) to 7.58 (3.41) g/d was observed between 2003 and 2014 ( P < 0.01), followed by an increase to 8.39 (4.13) g/d in 2018 ( P < 0.01). Similar trends in BP and CVD mortality were also observed between 2003 and 2018. SBP/DBP decreased from 125.3 (15.92)/74.48 (11.33) mmHg to 122.57 (14.92)/73.33 (10.75) mmHg between 2003 and 2014 ( P < 0.01), followed by a plateau up to 2018 [122.04 (14.64)/73.84 (10.54) mmHg, P > 0.05]. Likewise, a fall in stroke and ischaemic heart disease mortality rates was observed between 2003 and 2014, from 12.24 and 43.44 cases per 100 000, to 8.19 and 27.23 cases per 100 000 ( P < 0.01), respectively, followed by a plateau afterwards ( P > 0.05). The UK salt reduction programme was initially successful in reducing population salt intake by 19% (from 9.38 g/d in 2003 to 7.58 g/d in 2014). However, in recent years, the programme stalled and thus led to an interruption in the decline of salt intake. BP and CVD mortality reduction was also interrupted when salt reduction stalled. The changes in salt intake may have played an important role in the concomitant changes in BP and CVD mortality. Urgent action is needed to reinvigorate the UK's once world-leading salt reduction programme.

Is a spot urine sample a good substitution to estimate 24-h urinary sodium excretion in a population ≥ 50years old? A validation study.

A variety of prediction equations have been able to estimate 24-h urinary sodium excretion from spot urine samples; however, Iranians over the age of 50 have not been compared and verified. Using spot urine samples as a substitute for 24-h urine samples to estimate 24-h urine sodium excretion among the population age 50 and older are the purpose of this study. A 24-h urinary sodium excretion was studied by well-known Kawasaki, INTERSALT, Tanaka, and World Health Organization/Pan American Health Organization (WHO/PAHO) formulas. On 360 individuals, the mean bias, agreements between estimated and measured values, correlation, absolute and relative differences, and misclassification rates were evaluated for four equations. As a result, the mean urinary sodium excretion for a 24-h period was 136.3 ± 52.21mmol/24-h, which corresponds to a calculated intake of 9.1 ± 3.8g of salt per day. According to the WHO/PAHO formula, the mean bias between measured values and estimated 24-h urinary sodium excretion is - 21.6mg/day (95% confidence interval (CI) - 144.8, 101.6mg/day), which is the smallest difference compared with the other three formulas. The lowest rate of individual misclassification of salt intake was 40% for WHO/PAHO, especially for those who consumed less than 9g/day, while Kawasaki had the lowest misclassification rate at higher levels of salt intake. As a result of our research, the WHO/PAHO equations accurately predict 24-h urinary sodium excretion among Iranians aged ≥ 50 more than other equations, both at the population level and at the individual level. However, further study is needed in regard to different ages in Iran.

Outcomes of a state-wide salt reduction initiative in adults living in Victoria, Australia.

To assess any effects of a state-wide sodium reduction intervention on sodium intake, sources of dietary sodium and discretionary salt use at a population level. Data (24-h urinary sodium excretion, self-report survey, a 24-h dietary recall) were collected cross-sectionally at baseline (2016/2017) and follow-up (2020) from adults in Victoria, Australia. Intervention activities included consumer awareness advertising campaign, public debate generation via mass media, strengthening existing policy initiatives and supporting food innovation with industry. There were 339 participants at baseline and 211 at follow-up, with 144 and 90 of participants completing a 24-h dietary recall, respectively. There was no difference in adjusted 24-h urinary sodium excretion between baseline and follow-up (134 vs 131mmol/24h; p = 0.260). There were no differences in the percentage of participants adding salt during cooking (63% vs 68%; p = 0.244), adding salt at the table (34% vs 37%; p = 0.400) or regularly taking action to control salt/sodium intake (22% vs 21%; p = 0.793). There were large differences in the quantity of dietary sodium sourced from retail stores (57% vs 77%, p < 0.001), and less sodium was sourced from foods at fresh food markets (13% vs 2%; p ≤ 0.001) at follow-up. No large differences were apparent for foods with different levels of processing or for food groups. There was no clear population-level effect of the 4-year multi-component Victorian Salt Reduction Intervention on sodium intake with Victorian adults continuing to consume sodium above recommended levels. The findings indicate that more intensive and sustained efforts aiming at the retail and food industry with national level support are likely to be required to achieve a measurable improvement in sodium intake at a state level.

Awareness and Use of Low-Sodium Salt Substitutes and Its Impact on 24-h Urinary Sodium and Potassium Excretion in China-A Cross-Sectional Study.

The use of low-sodium salt substitute (LSSS) has the potential to reduce sodium and increase potassium intake. LSSS has been available in the Chinese market for years. However, its real-world use and impact on sodium/potassium intake is unclear. Baseline data of 4000 adult individuals who participated in three similarly designed randomized controlled trials were pooled together for this analysis. Self-reported awareness and use of LSSS were collected using a standardized questionnaire, and the participants' 24-h urinary sodium and potassium excretion was used to estimate their dietary intake. Mixed-effects models were developed to assess the relationship between LSSS and 24-h urinary sodium and potassium excretion. 32.0% of the participants reported awareness of LSSS and 11.7% reported its current use. After adjusting for location, sex, age, and education, compared with the group of participants unaware of LSSS, participants who were aware of but not using LSSS and those who were using LSSS had a lower 24-h urinary sodium excretion by -356.1 (95% CI: -503.9, -205.9) mg/d and -490.6 (95% CI: -679.2, -293.7) mg/d, respectively (p < 0.001). No significant difference was found for 24-h urinary potassium excretion or sodium-to-potassium ratio among the three groups (p > 0.05). In conclusion, the findings of low usage of LSSS and the reduced urinary sodium excretion associated with the awareness and use of LSSS provide further support for the prometon of LSSS as a key salt reduction strategy in China.

Evaluation of salt intake estimated from 24-h urinary sodium excretion in medical professionals in Darkhan-Uul Province, Mongolia: a cross-sectional study

This cross-sectional study aimed to estimate the daily salt intake of medical professionals working in public health facilities in Darkhan-Uul Province, Mongolia. We conducted a multiple logistic regression analysis to identify factors associated with their consumption of salt exceeding the recommended daily salt intake (≥ 5 g/day). A self-administered questionnaire and 24-h urine samples were used to obtain data on the participants’ salt intake. Of 338 participants, 159 completed the 24-h urine collection. The mean sodium excretion into urine was 122.3 mmol/day, which was equivalent to a mean salt intake of 7.7 g/day when the urinary excretion rate was considered as 93%. Body mass index was positively correlated with excess salt intake (adjusted odds ratio [AOR]: 1.27; 95% confidence interval [CI] 1.10–1.46), while age was negatively correlated with excess salt intake (AOR: 0.95; 95% CI 0.91–1.00). Participants who consumed ≥ 2 cups of salted suutei tsai (Mongolian milk tea) daily had a higher risk of consuming ≥ 5 g/day of salt than those who consumed ≤ 1 cup/day. The average estimated salt intake of the participants was higher than the recommended value. Medical professionals should be aware of factors associated with excessive salt consumption and make appropriate adjustments to minimize it.

Effect of γ-tocopherol supplementation on premenstrual symptoms and natriuresis: a randomized, double-blind, placebo-controlled study

BackgroundThis randomized, double-blind, placebo-controlled study aimed to investigate the effects of γ-tocopherol (Toc) supplementation on premenstrual symptoms and natriuresis.MethodsWe enrolled 51 Japanese women with premenstrual symptoms, particularly those who showed increased symptoms induced by water retention during the luteal phase compared with the follicular phase. Premenstrual symptoms were recorded in the first cycle’s postmenstrual follicular phase; physical measurements and urine collection were conducted during the 48-h run-in period. The test supplement, which contained 180 mg of γ-Toc or placebo, was orally administered twice a day for 7 days during the luteal phase of the first and second cycles in a crossover manner. The same evaluation was conducted during the luteal phase, beginning in the morning of the sixth day of supplement administration.ResultsCompared with placebo intake, γ-Toc intake significantly reduced “fatigue” and “irritability/anger” symptoms. Furthermore, compared with placebo intake, γ-Toc intake significantly reduced the thigh circumference. Regarding the “swelling of the legs” and “heavy legs” symptoms and the thigh circumference, the biphasic trend of increasing and decreasing values in the daytime and morning, respectively, during the follicular phase was not observed at the luteal phase with placebo intake. Contrastingly, γ-Toc intake resulted in significantly lower values in the morning than placebo intake. The mean difference in 24-h urinary sodium excretion between γ-Toc and placebo intake was 10.6 mEq (95% confidence interval (CI): -0.1, 21.4, p = 0.05, power 55%). Plasma γ-Toc and its metabolite γ-carboxyethyl hydroxychroman (CEHC) levels were significantly higher with γ-Toc intake than with placebo intake. There were no significant between-supplement differences in serum electrolyte levels or cumulative urinary potassium excretion.Conclusionγ-Toc intake could effectively alleviate certain premenstrual syndrome symptoms, particularly those related to water retention during the luteal phase. Furthermore, the underlying mechanism may involve the diuretic effect of γ-CEHC, which is a γ-Toc metabolite.Trial registrationUMIN000047989; registration date: 10/06/2022, retrospectively registered.

Estimated 24-h urinary sodium excretion and risk of end-stage kidney disease

The association between sodium intake and long-term kidney disease endpoints is debated and yet to be proven. We aimed to investigate the associations of estimated 24-h urinary sodium excretion, reflecting daily sodium intake, with the incidence of end-stage kidney disease (ESKD). In this prospective cohort study including 444,375UK Biobank participant, 865 (0.2%) ESKD events occurred after median follow-up of 12.7 years. For every 1g increment in estimated 24-h urinary sodium excretion, multivariable-adjusted hazard ratio for incident ESKD was 1.09 (95% confidence interval 0.94-1.26). Nonlinear associations were not detected with restricted cubic splines. The null findings were confirmed by a series of sensitivity analyses, which attenuated potential bias from measurement errors of the exposure, regression dilution, reverse causality, and competing risks. In conclusion, there is insufficient evidence that estimated 24-h urinary sodium excretion is associated with the incidence of ESKD.

Iodine intake assessment in the staff of a Porto region university (Portugal): the iMC Salt trial

PurposeIodine deficiency disorder (IDD) is an ongoing worldwide recognized problem with over two billion individuals having insufficient iodine intake. School-aged children and pregnant women are often target groups for epidemiological studies, but there is a lack of knowledge on the general adult population. The aim of this study was to assess the iodine status among a Portuguese public university staff as a proxy for the adult working population.MethodsThe population study covered 103 adults within the iMC Salt randomized clinical trial, aged 24–69 years. Urinary iodine concentration was measured spectrophotometrically using the Sandell–Kolthoff reaction. Iodine food intake was assessed using a 24-h dietary recall. The contribution of discretionary salt to the iodine daily intake was assessed through 24-h urinary sodium excretion (UIE) and potentiometric iodine determination of household salt.ResultsThe mean urine volume in 24 h was 1.5 L. The median daily iodine intake estimated from 24-h UIE was 113 µg/day, being lower among women (p < 0.05). Only 22% of participants showed iodine intake above the WHO-recommended cutoff (150 µg/day). The median daily iodine intake estimated from the 24-h dietary recall was 58 µg/day (51 and 68 µg/day in women and men, respectively). Dairy, including yoghurt and milk products, were the primary dietary iodine source (55%). Iodine intake estimated from 24-h UIE and 24-h dietary recall was moderately correlated (Spearman rank correlation coefficient r = 0.34, p < 0.05). The average iodine concentration in household salt was 14 mg I/kg, with 45% of the samples below the minimum threshold preconized by WHO (15 mg I/kg). The contribution of discretionary salt to the daily iodine intake was around 38%.ConclusionThis study contributes new knowledge about iodine status in Portuguese working adults. The results revealed moderate iodine deficiency, particularly in women. Public health strategies and monitoring programs are needed to ensure iodine adequacy in all population groups.

Estimated 24-Hour urinary sodium and potassium excretion in adults in the Northwest Region of Morocco, 2017

BackgroundExcessive sodium (Na) and insufficient potassium (K) intake contribute to a high risk of cardiovascular events. Morocco lacks data on actual Na and K intake in adults. We estimated mean Na and K intake in a Moroccan population of adults residing in the Northwest region using 24-h urinary excretion and examined their association with blood pressure (BP).MethodsA total of 371 adults from this region, who were recruited for the STEPs Survey Morocco 2017, completed demographic, anthropometric as well as BP data and provided a valid 24-h urine collection according to the standard World Health Organization (WHO) protocol. Multiple Linear Regression analysis was used to examine the association between 24-h urinary sodium (24-hUNa) and 24-h potassium excretion (24-hUK) with BP.ResultsMean Na excretion was 2794 mg/day and mean K excretion was 1898 mg/day. Overall, only 114 (30.7%) adults met the WHO recommendation for Na intake (< 2000 mg/d) and 31 (8.4%) met the adequate level for K intake (⩾3510 mg/d). There was no association between 24-hUNa and 24-hUK with BP (P > 0.05 for all).ConclusionNa intake was higher and K intake was lower than WHO recommendations in the study population. There was no association between estimated Na and K intake levels with BP in this population.

Blood pressure and cardiovascular risk in relation to birth weight and urinary sodium: an individual-participant meta-analysis of European family-based population studies.

Although the relation of salt intake with blood pressure (BP) is linear, it is U-shaped for mortality and cardiovascular disease (CVD). This individual-participant meta-analysis explored whether the relation of hypertension, death or CVD with 24-h urinary sodium excretion (UVNA) or sodium-to-potassium (UNAK) ratio was modified by birth weight. Families were randomly enrolled in the Flemish Study on Genes, Environment and Health Outcomes (1985-2004) and the European Project on Genes in Hypertension (1999-2001). Categories of birth weight, UVNA and UNAK (≤2500, >2500-4000, >4000 g; <2.3, 2.3-4.6 and >4.6 g; and <1, 1-2, >2, respectively) were coded using deviation-from-mean coding and analyzed by Kaplan-Meier survival functions and linear and Cox regression. The study population was subdivided into the Outcome ( n = 1945), Hypertension ( n = 1460) and Blood Pressure cohorts ( n = 1039) to analyze the incidence of mortality and cardiovascular endpoints, hypertension and BP changes as function of UVNA changes. The prevalence of low/medium/high birth weight in the Outcome cohort was 5.8/84.5/9.7%. Over 16.7 years (median), rates were 4.9, 8 and 27.1% for mortality, CVD and hypertension, respectively, but were not associated with birth weight. Multivariable-adjusted hazard ratios were not significant for any endpoint in any of the birth weight, UVNA and UNAK strata. Adult body weight tracked with birth weight ( P < 0.0001). The partial r in the low-birth-weight group associating changes from baseline to follow-up in UVNA and SBP was 0.68 ( P = 0.023) but not significant in other birth weight groups. This study did not substantiate its prior hypothesis but showed tracking of adult with birth weight and suggest that low birth weight increases salt sensitivity.

Moderate dietary salt restriction improves blood pressure and mental well-being in patients with primary aldosteronism: The salt CONNtrol trial.

Primary aldosteronism (PA) is a frequent cause of hypertension. Aldosterone excess together with high dietary salt intake aggravates cardiovascular damage, despite guideline-recommended mineralocorticoid receptor antagonist (MRA) treatment. To investigate the antihypertensive impact of a moderate dietary salt restriction and associated physiological changes, including mental well-being. A total of 41 patients with PA on a stable antihypertensive regimen-including MRA-followed a dietary salt restriction for 12 weeks with structured nutritional training and consolidation by a mobile health app. Salt intake and adherence were monitored every 4 weeks using 24-h urinary sodium excretion and nutrition protocols. Body composition was assessed by bioimpedance analysis and mental well-being by validated questionnaires. Dietary salt intake significantly decreased from 9.1 to 5.2g/d at the end of the study. In parallel, systolic (130 vs. 121mmHg) and diastolic blood pressure (BP) (84 vs. 81mmHg) improved significantly. Patients' aptitude of estimating dietary salt content was refined significantly (underestimation by 2.4 vs. 1.4g/d). Salt restriction entailed a significant weight loss of 1.4kg, improvement in pulse pressure (46 vs. 40mmHg) and normalization of depressive symptoms (PHQD scale, p<0.05). Salt restriction, cortisol after dexamethasone suppression test and dosage of renin-angiotensin-aldosterone-system (RAAS) blockers were independently associated with BP reduction. A moderate restriction of dietary salt intake in patients with PA substantially reduces BP and depressive symptoms. Moreover, the findings underline that a sufficient RAAS blockade seems to augment the effects of salt restriction on BP and cardiovascular risk.

The effect of orally administered nitrate on renal function and blood pressure in a randomized, placebo-controlled, crossover study in healthy subjects

BackgroundSeveral studies have shown inorganic nitrate/nitrite to reduce blood pressure in both healthy subjects and hypertensive patients. An effect presumably caused through bioconversion to nitric oxide. However, studies on inorganic nitrate/nitrite have shown inconsistent results on renal functions such as GFR and sodium excretion. The current study investigated whether orally administered nitrate would decrease blood pressure and increase GFR and urinary sodium excretion. MethodsIn a randomized, placebo-controlled, double-blinded, crossover study, 18 healthy subjects received a daily dose of 24 mmol potassium nitrate and placebo (potassium chloride) during 4 days in a randomized order. Subjects also ingested a standardized diet and completed a 24-h urine collection. GFR was determined by the constant infusion technique and during GFR measurement, brachial blood pressure (BP) and central blood pressure (cBP), heart rate, and arterial stiffness were measured every half hour using the Mobil-O-Graph®. Blood samples was analyzed for nitrate, nitrite, cGMP, vasoactive hormones and electrolytes. Urine was analyzed for nitrate, nitrite, cGMP, electrolytes, ENaCγ, NCC, CrCl, CH2O and UO. ResultsNo differences in GFR, blood pressure or sodium excretion were found between the treatments with potassium nitrate and placebo. However, both nitrate and nitrite levels in plasma and urine were significantly increased by potassium nitrate intake and the 24-h urinary excretion of sodium and potassium were stable, showing adherence to the standardized diet and the study medication. ConclusionWe found no decrease in blood pressure or increase in GFR and sodium excretion of 24 mmol potassium nitrate capsules as compared to placebo after 4 days of treatment.Healthy subjects may be able to compensate the effects of nitrate supplementation during steady state conditions. Future research should focus on long-term studies on the difference in response between healthy subjects and patients with cardiac or renal disease.

Renin, Aldosterone, and Cortisol in Pregnancy-Induced Hypertension.

We aimed to assess renin, aldosterone, and cortisol in the early stages of pregnancy-induced hypertension (PIH), i. e., at the time of diagnosis. During the postural test, we measured aldosterone, renin [Liason DiaSorin Inc. (Italy)], as well as cortisol, sodium, potassium, and 24-h urinary sodium and potassium excretion in 62 women with newly diagnosed PIH, 70 healthy women during the 3rd trimester of pregnancy, and in 22 healthy non-pregnant women. In all groups, there was a significant increase in aldosterone and renin in upright versus supine posture (p<0.01). Both supine and upright aldosterone concentrations were higher in healthy pregnant women than in women with PIH and the lowest in healthy not-pregnant [supine (median±intequartile range): 25.04±18.4 ng/dL, 18.03±12.58 ng/dL, and 7.48±4.78 ng/dL, p<0.001, upright: 31.60±21.32 ng/dL, 25.11±13.15 ng/dL, and 12.4±12.4 ng/dL, p<0.001, for healthy pregnant, pregnant with PIH, and non-pregnant, respectively]. Supine renin concentrations were higher only in healthy pregnant (p<0.001), while in the upright position, there was a difference only between healthy pregnant and women with PIH (p=0.002). Both in supine and upright positions, there was no difference in the aldosterone-to-renin ratio between healthy pregnant women and women with PIH, though, in both groups, the ratio was higher than in non-pregnant women (p<0.001). Morning cortisol concentrations and 24-h urinary sodium excretion were lower in women with PIH than in healthy pregnant (p<0.001, p=0.002, respectively). Hyperaldosteronism is not involved in the etiology of PIH. In PIH, there is also a tendency towards lower sodium excretion and lower morning cortisol concentrations.

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.

Urine 24-Hour Sodium Excretion Decreased between 1953 and 2014 in Japan,but Estimated Intake Still Exceeds the WHO Recommendation

Background: Accurate monitoring of sodium intake is necessary for evaluating strategies used to reduce sodium intake. However, no repeat survey has been conducted in representative populations in Japan to examine trends in sodium intake with the use of 24-h urinary sodium excretion, a standard evaluation method for sodium intake monitoring.Objective: The objective of this study was to examine potential trends in sodium intake by examining previous reports of 24-h urinary sodium excretion in healthy Japanese adult populations.Methods: We systematically searched for reports of 24-h urinary sodium excretion in healthy Japanese adult populations (mean age range: 18-69 y). We searched PubMed and Web of Science for English-language articles and hand-searched 7 Japanese scientific journals for Japanese-language articles. Trends in urinary sodium excretion were examined with the use of weighted linear regression and random-effects meta-regression analyses, with adjustment or stratification to address study characteristics (population mean age, percentage of men, and sample size) and study assessment for completeness of urine collection.Results: We identified 68 reports of urinary sodium excretion from 53 articles published from 1953 through 2014 that showed high rates of urinary sodium excretion in healthy Japanese adult populations (weighted mean: 4900 mg/d). The rate of urinary sodium excretion significantly decreased between 1953 and 2014, by 4350 mg/d (P < 0.001); however, the rate of reduction in urinary sodium excretion was variable and decreased with time (P-linear trend <0.001 and P-quadratic trend <0.001). In the random-effects meta-regression analysis of studies that assessed completeness of urine collection with creatinine excretion, no significant relation between urinary sodium excretion and year was observed from 1978 to 2014 (β = -16, P = 0.40).Conclusion: Despite a decrease in urinary sodium excretion in healthy Japanese adult populations between 1953 and 2014, sodium intake still exceeds the WHO recommendation for adults. This review was registered at PROSPERO as CRD42016035452.

Association of 24-h urinary sodium excretion with microalbuminuria in a Chinese population

To assess the relationship of sodium, potassium and the ratio of sodium to potassium (Na/K) with albuminuria, a cross-sectional study was carried out in China in 2017. Sodium, potassium and albumin excretions were examined in a 24-h (h) urine sample collected from 1486 participants. Microalbuminuria was defined as 24-h urinary albumin excretion between 30 and 300 mg/24 h. The participants had an average age of 46.2 ± 14.1 years old, and 48.9% were men. The proportion of patients with microalbuminuria was 9.0%. As illustrated by the adjusted generalized linear mixed model, sodium concentration increased significantly with the increase in 24-h urinary albumin (β = 1.16, 95% confidence interval (CI) 0.38–1.93; P = 0.003). Multivariable-adjusted logistic regression analyses demonstrated that the odds ratio (OR) of microalbuminuria increased with the quartiles of sodium [OR = 2.20, 95% CI 1.26–3.84 (the maximum quartile vs. the minimum quartile), Pfor trend = 0.006]. Potassium and the Na/K ratio did not have any association with outcome indicators. A high amount of sodium intake was potentially correlated with early renal function impairment.

S-54-4: DIETARY SALT INTAKE ASSESSED BY SPOT URINARY SODIUM EXCRETION FROM CHILD TO ADULTHOOD IN A JAPANESE TOWN

In clinical practice, a high salt intake is strongly associated with elevation of blood pressure. To prevent and treat hypertension, it is important to restrict salt in one’s diet from child and adolescence. However, data are lacking regarding dietary salt intake from child to adulthood in general population. Therefore, we evaluated the dietary salt intake assessed by spot urinary sodium excretion from child to adulthood in a Japanese town. A total of 534 persons of both sexes, aged from 3 to 91 years were under study. The Tanaka formula was used to estimate 24-h urinary sodium excretion, which reflects salt intake. The average salt intake was 8.0 ± 2.7 g/day (n = 534); that of the men was 8.2 ± 2.8 g/day (n = 206), and that of the women was 7.8 ± 2.6 g/day (n = 249). When we assessed by age group, the average salt intake was 3.8 ± 2.2 g/day in 3 years old (n = 79), 6.8 ± 1.5 g/day in 11 years old (n = 36), 8.0 ± 1.5 g/day in 14 years old (n = 37), 8.6 ± 2.8 g/day in 20 s and 30 s (n = 37), 8.0 ± 1.7 g/day in 40 s (n = 24), 8.9 ± 2.2 g/day in 50 s (n = 32), 8.9 ± 2.1 g/day in 60 s (n = 108), 9.2 ± 1.9 g/day in 70 s (n = 182), and 9.0 ± 2.2 g/day in over 80 s (n = 22). Notably, dietary salt intake was over 6 g/day even in 11 years old. The salt intake was significantly higher in the older age group (P &lt; 0.001 for trend) and was significantly associated with higher systolic and diastolic blood pressure. In conclusion, it is important to educate children, their parents, childcare professionals, and society about proper salt restriction and potassium supplementation, as well as to improve the food environment.

Estimating population level 24-h sodium excretion using spot urine samples in older adults in rural South Africa.

South Africa has introduced regulations to reduce sodium in processed foods. Assessing salt consumption with 24-h urine collection is logistically challenging and expensive. We assess the accuracy of using spot urine samples to estimate 24-h urine sodium (24hrUNa) excretion at the population level in a cohort of older adults in rural South Africa. 24hrUNa excretion was measured and compared to that estimated from matched spot urine samples in 399 individuals, aged 40-75 years, from rural Mpumalanga, South Africa. We used the Tanaka, Kawasaki, International Study of Sodium, Potassium, and Blood Pressure (INTERSALT), and Population Mean Volume (PMV) method to predict 24hrUNa at the individual and population level. The population median 24hrUNa excretion from our samples collected in 2017 was 2.6 g (interquartile range: 1.53-4.21) equal to an average daily salt intake of 6.6 g, whereas 65.4% of participants had a salt excretion above the WHO recommended 5 g/day. Estimated population median 24hrUNa derived from the INTERSALT, both with and without potassium, showed a nonsignificant difference of 0.25 g (P = 0.59) and 0.21 g (P = 0.67), respectively. In contrast, the Tanaka, Kawasaki, and PMV formulas were markedly higher than the measured 24hrUNa, with a median difference of 0.51 g (P = 0.004), 0.99 g (P = 0.00), and 1.05 g (P = 0.00) respectively. All formulas however performed poorly when predicting an individual's 24hrUNa. In this population, the INTERSALT formulas are a well suited and cost-effective alternative to 24-h urine collection for the evaluation of population median 24hrUNa excretion. This could play an important role for governments and public health agencies in evaluating local salt regulations and identifying at-risk populations.

Salt-Related Knowledge, Attitudes, and Behaviors and Their Relationship with 24-Hour Urinary Sodium Excretion in Chinese Adults.

Salt intake in China is very high, which increases the risk of hypertension and cardiovascular disease. This study aimed to assess the levels of salt-related knowledge, attitudes, and behaviors (KABs) and the factors that influence them and to explore the relationship between the scores of salt-related KAB and 24-h urinary sodium excretion. In 2018, we collected data from 5453 individuals aged 18–75 years from six provinces in China. A face-to-face survey was carried out, focusing on the KAB related to salt reduction. All participants were asked to collect one 24-h urine sample. Of the 5453 participants, 5352 completed urine collection. The mean score for overall KAB was 31.27 (SD = 9.18), which was composed of three elements: knowledge 4.80 (SD = 5.14), attitude 9.33 (SD = 3.93), and behavior 17.14 (SD = 4.43). The average 24-h urinary sodium excretion was 187.70 (SD = 77.48) mmol, which was equivalent to a urinary sodium excretion of 4.32 (SD = 1.78) g/d. We found that salt-related knowledge, attitude, behavior, and overall KAB scores were all inversely associated with 24-h urinary sodium excretion. For every one-point increase in the KAB score, the 24-h urinary sodium excretion decreased by 0.851 mmol (95% CI: −1.095, −0.602). We also found that location (rural/urban), sex, age, and education are associated with salt-related KAB scores. These results suggest that large-scale health education is needed to reduce salt intake in the Chinese population. In particular, efforts should be focused on reaching those who live in rural areas with low educational levels and older people.

The association between dietary sodium intake and osteoporosis

The association of inadequate dietary sodium intake with bone mineral density (BMD) and the risk of osteoporosis is controversial. To find the association between low sodium diet and the risk of incipient osteoporosis, we performed a population-based cross-sectional analysis using Tanaka method for estimation 24-h urinary sodium excretion (e24hUNaETanaka) as a candidate indicator of sodium intake. We identified 3869 participants without osteoporosis and classified them into quartiles according to their value of e24hUNaETanaka. BMD was measured to find participants at risk of osteoporosis. Lower e24hUNaETanaka was related to decreasing BMD of the distal radius. Multiple Cox-proportional hazard models demonstrated that e24hUNaETanaka had an inverse association with the risk of osteoporosis (adjusted HR = 0.859, 95% CI = 0.751–0.982) and survival analysis revealed that the lowest quartile group had poor osteoporosis-free survival (PLog-rank < 0.0001). Furthermore, our restricted cubic spline analysis revealed that the relationship between e24hUNaETanaka and HR of osteoporosis was negative curvilinear in males and postmenopausal females and positive linear in premenopausal females. Our findings suggest that lower sodium intake was a significant predictor of incipient osteoporosis and there was wide variation in this relationship according to sex and female hormone status.