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Abstract Accurate measurement of sodium intake in the diet is challenging, and epidemiological studies can be hampered by the attenuation of associations due to measurement error in sodium intake. A prediction formula for habitual 24-h urine sodium excretion and sodium-to-potassium ratio might lead to more reliable conclusions. Five 24-h urinary samples and two Food Frequency Questionnaires (FFQs) were conducted among 244 Japanese participants aged 35–80 years. We conducted multivariate linear regression analysis with urinary excretion as dependent variables and eating behaviour and food frequency as independent variables. Empirical weights of sodium excretion and sodium-to-potassium ratio were extracted. Preliminary validity was also assessed by randomly dividing the subjects into development and validation groups based on the correlation coefficient between estimates by the prediction formula and urinary excretion. Taste preference, soy sauce use at the table, frequency of pickled vegetables intake and number of bowls of miso soup were extracted as determinants of sodium excretion. Correlation coefficients between the estimates and urinary excretion for men and women were 0.42 and 0.43, respectively, for sodium and 0.49 and 0.50, respectively, for sodium-to-potassium ratio. This prediction formula may provide more accurate estimation of sodium intake and sodium-to-potassium ratio than the food composition approach.

This cross-sectional study evaluated the validity of three alternative methods compared to the gold standard 24-h urine collection for estimating dietary sodium intake, a modifiable risk factor for hypertension, among middle-aged and older adults with elevated blood pressure. These included spot urine collection (using Kawasaki, Tanaka, and INTERSALT equations), 24-h dietary recall, and food frequency questionnaire responses, compared to 24-h urine collection in a subset of 65 participants (aged 50–75 years, 58.5% women, 61.6% hypertensive) from the DePEC-Nutrition trial. The validity of the methods was assessed using bias, the Spearman correlation coefficient (SCC), the intraclass correlation coefficient (ICC), and Bland–Altman analysis. Among the alternative methods, spot urine collection using the Kawasaki equation showed the strongest correlation (SCC 0.238; ICC 0.119, 95% CI −0.079 to 0.323), but it exhibited a significant bias (1414 mg/day, p-value < 0.001) relative to 24-h urine collection. Conversely, dietary surveys had a smaller bias but wider limits of agreement. These findings underscore the complexities of accurately estimating dietary sodium intake using spot urine collection or dietary surveys in this specific population, suggesting that a combination or the refinement of existing methodologies might improve accuracy. Further research with larger samples is necessary to develop more reliable methods for assessing sodium intake in this high-risk group. [ABSTRACT FROM AUTHOR]

Accurate measurement of sodium intake in the diet is challenging, and epidemiological studies can be hampered by the attenuation of associations due to measurement error in sodium intake. A prediction formula for habitual 24-h urine sodium excretion and sodium-to-potassium ratio might lead to more reliable conclusions. Five 24-h urinary samples and two Food Frequency Questionnaires (FFQs) were conducted among 244 Japanese participants aged 35–80 years. We conducted multivariate linear regression analysis with urinary excretion as dependent variables and eating behaviour and food frequency as independent variables. Empirical weights of sodium excretion and sodium-to-potassium ratio were extracted. Preliminary validity was also assessed by randomly dividing the subjects into development and validation groups based on the correlation coefficient between estimates by the prediction formula and urinary excretion. Taste preference, soy sauce use at the table, frequency of pickled vegetables intake and number of bowls of miso soup were extracted as determinants of sodium excretion. Correlation coefficients between the estimates and urinary excretion for men and women were 0.42 and 0.43, respectively, for sodium and 0.49 and 0.50, respectively, for sodium-to-potassium ratio. This prediction formula may provide more accurate estimation of sodium intake and sodium-to-potassium ratio than the food composition approach. [ABSTRACT FROM AUTHOR]

Abstract Background Urologic guidelines universally recommend increasing fluid intake for kidney stone prevention. Increased voided volume is thought to help reduce stone recurrence and severity, but supporting evidence is limited. Patients and Methods Nephrolithiasis outcomes and 24‐h urine data for patients from the Registry for Stones of the Kidney and Ureter (ReSKU), a registry of nephrolithiasis patients collected between 2015 and 2020, were retrospectively analysed. Outcome was stone events, either an office visit where a patient reports symptomatic passage of stones or surgery for stone removal. Results We identified 450 stone patients with 24‐h urine and kidney stone outcome data. There was no significant difference in 24‐h voided volume between patients with one stone event and patients with two or more stone events. On multivariable logistic regression, after controlling for age, gender, BMI, and 24‐h sodium and creatinine per kilogram, no significant associations were found between voided volume and stone events. There was a statistically significant negative correlation noted between voided volume and stone events in calcium oxalate dihydrate stone formers (Spearman R = −0.42, p = 0.04), but not others. Conclusions Twenty‐four‐hour voided volume was not associated with stone events in a large institutional cohort, and subset analysis reveals that some stone formers may benefit more from increased voided volume than others; identifying such patients represents a novel precision medicine opportunity.

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. [ABSTRACT FROM AUTHOR]

Abstract Objectives To evaluate the effects of two vitamin D repletion therapies (cholecalciferol) on serum levels of 25-hydroxyvitamin D (25(OH)D) and 24-h urine calcium in patients with recurrent calcium kidney stones and vitamin D deficiency (VDD). Design, setting, participants A parallel-group randomized controlled clinical trial on patients who referred to Labbafinejad kidney stone prevention clinic, Tehran, Iran. From 88 recurrent calcium stone formers, 62 patients completed the study. The age of participants was 18–70 years who had serum 25(OH)D levels of 10–20 ng/ml. Intervention Participants received oral cholecalciferol 2000 IU daily for 12 weeks or 50,000 IU weekly for 8 weeks. Main outcome measures Study variables including 24-h urine calcium, supersaturations of calcium oxalate and calcium phosphate, serum 25(OH)D and parathyroid hormone were measured at the beginning of the study and after 12 weeks. Results The 24-h urine calcium significantly increased in both groups (β = 69.70, p

Abstract 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.

Objectives: To evaluate the effects of two vitamin D repletion therapies (cholecalciferol) on serum levels of 25-hydroxyvitamin D (25(OH)D) and 24-h urine calcium in patients with recurrent calcium kidney stones and vitamin D deficiency (VDD). Design, setting, participants: A parallel-group randomized controlled clinical trial on patients who referred to Labbafinejad kidney stone prevention clinic, Tehran, Iran. From 88 recurrent calcium stone formers, 62 patients completed the study. The age of participants was 18–70 years who had serum 25(OH)D levels of 10–20 ng/ml. Intervention: Participants received oral cholecalciferol 2000 IU daily for 12 weeks or 50,000 IU weekly for 8 weeks. Main outcome measures: Study variables including 24-h urine calcium, supersaturations of calcium oxalate and calcium phosphate, serum 25(OH)D and parathyroid hormone were measured at the beginning of the study and after 12 weeks. Results: The 24-h urine calcium significantly increased in both groups (β = 69.70, p < 0.001), with no significant difference between treatments. Both groups showed no significant change in the supersaturation levels of calcium oxalate and calcium phosphate. Serum levels of 25(OH)D increased significantly (β = 12.53, p < 0.001), with more increase in the 50,000 IU group (β = 3.46, p = 0.003). Serum parathyroid hormone decreased in both groups (p < 0.001). Conclusions: Although both treatment protocols increased 24-h urine calcium, they did not increase the supersaturation state of calcium oxalate or calcium phosphate. Trial registration IRCT20160206026406N4, 13/08/2019. [ABSTRACT FROM AUTHOR]

Reducing Na intake is an urgent global challenge, especially in East Asia and high-income Asia-Pacific regions. However, the sources of Na and their effects on urinary Na excretion have not been fully studied. We sought to clarify these sources and their association with urinary Na excretion. We examined four 3-d weighed food records and five 24-h urinary collections from each of 253 participants in Japan, aged 35–80 years, between 2012 and 2013. We compared the levels of Na according to four categories: foods contributing to discretionary or non-discretionary Na intake, the situation in which dishes were cooked and consumed, food groups and types of cuisine. We also conducted regression analysis in which 24-h urinary Na excretion was a dependent variable and the amounts of food intake in the four categories were independent variables. Levels of Na were the highest in discretionary intake (60·6 %) and in home-prepared dishes (84·0 %). Of the food groups, miso soup showed the highest percentage contribution to Na intake (13·3 %) after seasonings such as soya sauce. In the regression analysis, the standardised coefficient for foods of non-discretionary Na sources was larger than that for discretionary sources, whereas that for home-prepared dishes was consistent with the levels of Na in those foods. Pickled products, followed by fresh fish and shellfish, miso soup and rice, were associated with high urinary Na excretion. Thus, discretionary foods (such as miso soup) contribute the most to Na consumption, although non-discretionary intake (such as pickled vegetables) may influence urinary Na excretion. [ABSTRACT FROM AUTHOR]

Abstract Background High sodium and low potassium intakes are associated with the early development of chronic diseases (e.g., hypertension, obesity). Taking into account the limited data on sodium and potassium intakes by 24-h excretion in urine in pre-adolescents and adolescents, we wished to determine baseline salt intake in Iranian subjects aged 11–18 years. Methods This was an observational study involving 374 pre-adolescents and adolescents (154 boys and 220 girls). Sodium and potassium intakes were ascertained by measuring sodium and potassium excretion in urine over 24 h. Creatinine level was used to validate the completeness of the urine collections. The association between sodium and potassium intake and adiposity was determined based on body fat percentage. Results The mean 24-h urine sodium concentration was 3130 ± 2200 mg/day, equal to 7.961 ± 5.596 g/day salt intake. Approximately half of the study participants exceeded the upper limit of Na intake. The mean potassium intake was estimated 1480 ± 1050 mg/day. There was a positive association between urinary sodium excretion and adiposity in crude (OR 1.79; 95% CI: 1.08—2.74) and full adjusted model (OR: 3.15; 95% CI: 2.28–4.63). Also, in subsample analysis, there was a positive correlation between urinary sodium and adiposity in both pre-adolescents (OR: 2.71; 95% CI: 2.29—3.93) and adolescents (OR: 3.55; 95% CI: 2.17—4.74). However, no significant association was found between 24-h urinary potassium and adiposity. Conclusion Sodium intake, as estimated by 24-h urinary excretion, was higher than recommended and it was positively associated with adiposity. Also, this study reported low compliance of potassium intake recommendations in 11–18 years’ Iranian pre-adolescents and adolescents. Health promotion interventions are needed in order to broaden public awareness of high sodium intake and potassium inadequacy to reduce chronic diseases.

Objective: The connection between increased dietary salt intake and arterial hypertension has been recognized for a long time, even in children. This study aimed to investigate salt consumption in normotensive and hypertensive children and evaluate their dietary habits. Materials and Methods: A total of fifty participants were included in this cross-sectional study: twenty-five normotensive children and 25 children of both sexes with essential arterial hypertension from 12–17 years old. Subjects' body mass index, waist-to-hip ratio, body composition and arterial blood pressure were measured, and their daily salt intake was calculated from 24-h urine samples. Using the food frequency questionnaire (FFQ), the data on the average daily total energy and food intakes were collected and analyzed using a suitable program. Results: Estimated daily salt intake was significantly higher in hypertensive compared to normotensive children, and this is positively associated with blood pressure and body mass index (BMI). Hypertensive children had significantly higher BMIs, which also positively correlated with blood pressure. Consistently, resting metabolic rate (kcal) is higher in hypertensive children compared to normotensive, and this is also associated with blood pressure. Reported energy intake is also enlarged in hypertensive compared to normotensive children and for both groups, levels are significantly higher than the recommended values. Conclusions: Our study results confirm the relationship between daily salt consumption, blood pressure and body weight. Sodium consumption related to blood pressure and body weight among children. Cardiovascular disease prevention should start in early childhood by reducing salt intake and preventing overweight/obesity since these are two of the most important modifiable risk factors for hypertension. [ABSTRACT FROM AUTHOR]

IntroductionDiscretionary salt (added in cooking at home or at the table) is a source of sodium and iodine in New Zealand. The amount of discretionary salt consumed in a population has implications on policies regarding sodium and iodine. Sodium intake from discretionary salt intake has not been quantified in New Zealand. The aim of this study was to estimate the proportion of total sodium that comes from discretionary salt in adults using the lithium-tagged salt method.MethodsA total of 116 healthy adults, who were not pregnant or breastfeeding, regularly consume home-cooked meals and use salt during cooking or at the table, aged 18–40 years from Dunedin, New Zealand were recruited into the study. The study took place over a 9-day period. On Day 1, participants were asked to collect a baseline 24-h urine to establish their normal lithium output. From Day 2 to Day 8, normal discretionary salt was replaced with lithium-tagged salt. Between Day 6 and Day 8, participants collected another two 24-h urine samples. A 24-h dietary recall was conducted to coincide with each of the final two 24-h urine collections. Urinary sodium was analysed by Ion-Selective Electrode and urinary lithium and urinary iodine were analysed using Inductively Coupled Plasma Mass Spectrometry. The 24-h dietary recall data was entered into Xyris FoodWorks 10. All statistical analysis were conducted using Stata 17.0.ResultsA total of 109 participants with complete 24-h urine samples were included in the analysis. From the 24-h urine collections, the median urinary excretion of sodium and iodine was 3,222 mg/24 h (25th, 75th percentile: 2516, 3969) and 112 μg/24 h (82, 134). The median estimated sodium intake from discretionary salt was 13% (25th, 75th percentile: 7, 22) of the total sodium intake or 366 mg/24 h (25th, 75th percentile: 186, 705).ConclusionThe total sodium intake was higher than the suggested dietary target of 2,000 mg/day. In this sample of healthy adults 18 to 40 years old, 13% of total sodium intake derived from discretionary salt. Discretionary salt is an additional source of iodine if iodised salt is used. Policies to reduce sodium intake is recommended to include a range of strategies to target discretionary and non-discretionary sources of salt and will need to take into account the contribution of iodine from discretionary salt intake.

PurposeThis study aimed to evaluate the salt intake in boarding school students and the consistency between salt intake measurements based on 24-h urine and weighed dietary records over 3 consecutive days in this population.MethodsThis was a school-based cross-sectional study. Overweight (including obesity) or hypertensive students aged 6–14 years and their normal counterparts were recruited for this study at three boarding schools in China. Three consecutive 24-h urine samples were collected from all participants. During the collection period of 24-h urine, the weighed diet records were collected in children who had all three meals at the school canteens on weekdays. Incomplete 24-h urine or dietary records were excluded from the analysis.ResultsThe median salt excretion was 6,218 [4,636, 8,290] mg by 24-h urine and 120 (82.2%) consumed excess salt among the participants. The median salt intake was 8,132 [6,348, 9,370] mg by dietary records and 112 (97.4%) participants consumed excess salt than recommended in participants who have all three meals in the school canteens. In children with complete dietary records and 24-h urine, the level of salt intake estimated by 24-h urine accounted for 79.6% of the dietary records.ConclusionOur study showed that boarding school students consumed excessive salt from school canteens. Thus, policies or strategies targeting school canteens are urgently needed. Weighed dietary records are recommended if feasible.

Objective: Monitoring population salt intake is operationally and economically challenging. We explored whether a questionnaire assessment and a prediction of Na intake from spot-urine could replace or complement the recommended measurement of Na in 24-h urine (24-h U).Design: Compare the agreement of a Na-specific food record checklist (FRCL) and a late-afternoon spot-urine measurement (PM-spot) with 24-h U measurement in estimating Na intake at group level. Each participant's use of these methods extended over 3 d. Agreement was assessed using mean (95 % CI) differences, linear regression models and Bland-Altman plots.Setting: The validation study was part of a 1-year workplace intervention trial to lower salt intake in Switzerland.Participants: Seventy women and 71 men, aged 21-61 years, completed three FRCL, and acceptable PM-spot and 24-h U samples at baseline (April-October 2015).Results: Mean Na intake estimates varied slightly across methods (3·5-3·9 g/d). Mean Na intake differences from 24-h U were 0·2 (95 % CI (0, 0·5)) g/d for FRCL and 0·4 (95 % CI (0·2, 0·6)) g/d for PM-spot. Linear regression models and Bland-Altmann plots more clearly depicted differences by sex and discretionary salt use.Conclusions: Although 24-h U remains the best reference method for monitoring Na intake at the population level, PM-spot and FRCL might be more practical instruments for frequent, periodic Na intake assessments. Population-specific prediction models to estimate 24-h U could be developed and evaluated. [ABSTRACT FROM AUTHOR]

Background: Advances in technology have led to the identification of a greater number of metabolites related to diet. Although fruit intake biomarkers have been reported in some studies, these findings require further replication, considering the relevance of fruits for diet quality and health.Objectives: The aim of this study was to explore the associations of a set of potential urinary biomarkers of diet, assessed using a targeted metabolomics approach, with self-reported fruit intake data in participants of a computer-assisted 24-h dietary recall (GloboDiet software) validation study.Methods: A total of 93 individuals aged 43-72 y, 54% female, participated in this study. The subjects were a subsample of the Longitudinal Study of Adult Health (ELSA-Brasil). A 24-h dietary recall was obtained with the aid of GloboDiet software matching a 24-h urine sample from each participant. Candidate biomarkers were selected in a literature search and identified in urine by LC coupled to high-resolution MS. Spearman correlation analyses were performed between fruit intake and each biomarker.Results: Spearman correlation analysis showed that total fruits intake was significantly correlated with citric acid (ρ = 0.213, P = 0.041), ferulic acid sulfate I (ρ = 0.240, P = 0.020), hesperetin glucuronide/homoeriodictyol glucuronide (ρ = 0.303, P = 0.003), hydroxyhippuric acid (ρ = 0.239, P = 0.021), homovanillic alcohol sulfate (ρ = 0.339, P = 0.001), methylgallic acid sulfate (ρ = 0.268, P = 0.009), naringenin glucuronide (NG; ρ = 0.278, P = 0.007), proline betaine (PB; ρ = 0.305, P = 0.003), syringic acid sulfate (ρ = 0.210, P = 0.044), and sinapic acid sulfate (ρ = 0.412, P < 0.001). Among them, 3 have been described in literature as promising biomarkers for intake of total fruit, oranges, and citrus fruit: NG, hesperetin glucuronide, and PB.Conclusions: Associations of total fruits intake with urinary measurements indicate the potential usefulness of dietary biomarkers in the Brazilian population as a complement to self-reported dietary assessments. [ABSTRACT FROM AUTHOR]

Twenty-four-hour urine measurements play a crucial role in the diagnosis, follow-up and treatment of various diseases. There are different approaches to the collection of urine in patients who need to collect multiple urine samples at a time, especially in hospitals with heavy workloads. In this study, we compared the sodium, potassium, chloride, amylase, calcium, creatinine, phosphorus, microalbumin, protein, magnesium, urea, uric acid, adrenaline, noradrenaline, dopamine, metanephrine, normetanephrine, vanillylmandelic acid, 5-hydroxyindoleacetic acid and homovanillic acid results of 24-h urine samples analyzed immediately without acid addition, which we accepted as the reference and baseline measurement, with the results of the samples analyzed after waiting for 24 h without acid addition, analyzed immediately with acid addition and analyzed after waiting for 24 h with acid addition. Chloride, microalbumin, amylase and protein tests, which are recommended to be measured in the sample without preservatives, are affected by acid addition. Adrenaline, noradrenaline and dopamine, which are the tests recommended to be measured in acid-added urine are degraded in the samples without acid, and the levels of metanephrine and normetanephrine were not significantly degraded in the absence of preservatives. [ABSTRACT FROM AUTHOR]

Few studies have assessed the association between sodium (Na) and potassium (K) and migraine headaches. In this study, we aimed to examine the relationship between 24-hour urine Na and K intakes and clinical findings of migraine in an Iranian sample. In this cross-sectional study, 262 participants, aged 20–50 years, were included with a body mass index (BMI) of 18·5–30 kg/m2 and a diagnosis of migraine. One 24-hour urine sample was collected from each subject to estimate the Na and K intakes. The clinical features of migraine, including frequency, duration, severity, Migraine Headache Index Score (MHIS), and Headache Impact Test (HIT) score, were assessed. Besides, a multiple linear regression analysis was performed, and beta estimates and the corresponding 95% confidence intervals (CIs) were reported. Overall, 224 women and 38 men, with a mean age of 36·10 years and BMI of 25·55 kg/m2 comprised our study population. After controlling for potential confounders, the 24-hour urine Na was positively associated with a longer headache duration (β = 0·29; 95% CI: 0·06, 0·53) in the group with the highest urine Na levels as compared to the group with the lowest levels. After adjustments for potential confounders, an increase of 13·05 in the MHIS was observed when the 24-hour urine Na level increased from the first to the third tertile (β = 13·05; 95% CI: 1·70, 24·41). Our findings suggested that a higher 24-hour urine Na level was positively associated with a longer duration of migraine headaches and a higher MHIS. [ABSTRACT FROM AUTHOR]

Purpose: Mild-to-moderate iodine deficiency was present in large parts of Germany up to the beginning 1990s and improved from then on. Current epidemiological data on spot urine iodine measurements in German children strongly suggest the re-occurrence of an impaired iodine status. We thus examined whether this re-occurrence is identifiable in more detail, through iodine analyses of 24-h urine samples of a well-characterized cohort of German children in whom samples have been systematically collected from 1985 onward. As iodized salt is a major source for iodine supply, urinary sodium excretion was additionally studied. Methods: Daily iodine and sodium excretions were measured in 2600 24-h urine samples collected between 1985 and 2018 by 677 healthy children aged 6–12 years (participants of the DONALD study). These data were compared with 24-h iodine and sodium excretion estimates obtained from spot urine samples collected in the representative German Health Interview and Examination Surveys for Children and Adolescents KiGGS-baseline (2003–2006) and KiGGS-wave-2 (2014–2017). Results: Between 1985 and1992, DONALD participants started with a median daily iodine excretion level of 40.1 µg/d. Then, during 1993–2003, iodine excretions mounted up to an approximate plateau (~ 84.8 µg/d). This plateau lasted until 2012. Thereafter, iodine concentrations started to decrease again resulting in a median iodine excretion of only 58.9 µg/d in 2018. Sodium excretion, however, had increased. The marked decrease in iodine status along with an abundant sodium excretion corresponded closely with nationwide KiGGS data. Conclusions: As exemplified for the clearly worsening iodine status in German children, longitudinal cohort studies collecting detailed biomarker-based prospective data have the potential to reliably capture health-relevant nutritional changes and trends, applicable on a more comprehensive and even representative population level. [ABSTRACT FROM AUTHOR]

Background: High sodium and low potassium intakes are associated with the early development of chronic diseases (e.g., hypertension, obesity). Taking into account the limited data on sodium and potassium intakes by 24-h excretion in urine in pre-adolescents and adolescents, we wished to determine baseline salt intake in Iranian subjects aged 11-18 years.Methods: This was an observational study involving 374 pre-adolescents and adolescents (154 boys and 220 girls). Sodium and potassium intakes were ascertained by measuring sodium and potassium excretion in urine over 24 h. Creatinine level was used to validate the completeness of the urine collections. The association between sodium and potassium intake and adiposity was determined based on body fat percentage.Results: The mean 24-h urine sodium concentration was 3130 ± 2200 mg/day, equal to 7.961 ± 5.596 g/day salt intake. Approximately half of the study participants exceeded the upper limit of Na intake. The mean potassium intake was estimated 1480 ± 1050 mg/day. There was a positive association between urinary sodium excretion and adiposity in crude (OR 1.79; 95% CI: 1.08-2.74) and full adjusted model (OR: 3.15; 95% CI: 2.28-4.63). Also, in subsample analysis, there was a positive correlation between urinary sodium and adiposity in both pre-adolescents (OR: 2.71; 95% CI: 2.29-3.93) and adolescents (OR: 3.55; 95% CI: 2.17-4.74). However, no significant association was found between 24-h urinary potassium and adiposity.Conclusion: Sodium intake, as estimated by 24-h urinary excretion, was higher than recommended and it was positively associated with adiposity. Also, this study reported low compliance of potassium intake recommendations in 11-18 years' Iranian pre-adolescents and adolescents. Health promotion interventions are needed in order to broaden public awareness of high sodium intake and potassium inadequacy to reduce chronic diseases. [ABSTRACT FROM AUTHOR]

Abstract Background Little is known about the capacity of overnight and spot urine samples to estimate changes in mean salt intake over time. The objective of this review was to compare the estimates of change in mean population salt intake based on 24-h urine and overnight/spot urine samples. Methods Studies were systematically identified through searches of peer-reviewed databases (Medline, Embase, Global Health, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews) and grey literature. Studies that reported estimates of mean salt intake for at least two time points based on both 24-h and overnight/spot urines were deemed eligible. The capacity of overnight/spot urine samples to estimate the change in mean salt intake was assessed both at the individual-study level and overall through random-effects meta-analyses. The level of heterogeneity was assessed through the I2 statistic. Subgroup and sensitivity analyses were conducted to explore possible sources of heterogeneity, and check the robustness of the findings from the primary analysis. Results A total of 1244 records were identified, 50 were assessed as full text, and 14 studies met the criteria, capturing data on 7291 participants from seven countries. Nine and five studies collected overnight and spot urines, respectively. The comparison of the change in mean salt intake between 24-h and overnight/spot urines showed some inconsistencies at the individual study-level. The pooled mean change in salt intake was − 0.43 g/day (95% CI − 1.16 to 0.30; I2 = 95%) using 24-h urines, and − 0.22 g/day (− 0.65 to 0.20; I2 = 87%) using overnight/spot urines, with a pooled difference-in-differences between the two methods of 0.27 g/day (− 0.23 to 0.77; I2 = 89%). Subgroup analyses showed substantial heterogeneity for most subgroups. Sensitivity analyses did not change the effect observed in the primary analysis. Conclusion The evidence for the capacity of overnight/spot urines to estimate changes in mean salt intake over time is uncertain. More research where overnight/spot urines are collected in parallel with 24-h urines is needed to enable a more in-depth evaluation of these alternative approaches to estimating change in mean salt intake.

Abstract Background Patients with urolithiasis have a lower bone mineral density (BMD) than those without stones, suggesting a potential correlation between calcium stone formation and bone resorption disorders, including osteopenia and osteoporosis. Methods To investigate the influence of BMD on clinical outcomes in urolithiasis, we performed a single-center retrospective cohort study to analyze patients with urolithiasis who underwent both BMD examination and 24-h urine collection between 2006 and 2015. Data from the national cross-sectional surveillance of the Japanese Society on Urolithiasis Research in 2015 were utilized, and additional data related to urinary tract stones were obtained from medical records. The primary outcome was the development of stone-related symptoms and recurrences during follow-up. A total of 370 patients were included in this 10-year study period. Results Half of the patients had recurrent stones, and the two-thirds were symptomatic stone formers. While only 9% of patients had hypercalciuria, 27% and 55% had hyperoxaluria and hypocitraturia, respectively. There was a positive correlation between T-scores and urinary citrate excretion. Both univariate and multivariate analyses demonstrated that female sex was associated with recurrences (odds ratio = 0.44, p = 0.007), whereas a T-score

Background: Spot urine collection offers a convenient alternative to the more cumbersome 24-h urine collection. However, the widely recognized estimation models, such as Tanaka and International Cooperative Study on Salt, Other Factors, and Blood Pressure (INTERSALT), have not been adequately adapted for widespread use in the general Chinese population., Objectives: This study was designed to evaluate the precision of the Tanaka and INTERSALT calibration models, alongside a locally Zhejiang Province-formulated model, in predicting 24-h urinary sodium (24-hUNa) excretion among the Chinese population., Methods: The study comprised 1424 participants, aged 18-69 y, who provided both comprehensive 24-h urine and fasting morning urine samples. The researchers assessed the accuracy of the measured 24-hUNa against the estimates obtained from the Tanaka, INTERSALT, and Zhejiang models. This evaluation was conducted at both population and individual levels, employing a range of statistical techniques, including bias analysis, correlation coefficients, intraclass correlation coefficients, receiver operating characteristic curves, Bland-Altman plots, as well as relative and absolute difference calculations, and misclassification rates., Results: The measured average 24-hUNa excretion was found to be 165.7 ± 71.5 mmol/24-h. Notably, there was a significant deviation between the estimated and measured values for the Tanaka-adjusted model [-11.7 mmol, 95% confidence interval (CI): -16.7, -6.7 mmol/24-h], indicating a statistically significant difference. In contrast, the deviations for the INTERSALT-adjusted model (0.6 mmol, 95% CI: -4.2, 5.4 mmol/24-h) and the Zhejiang model (0.2 mmol, 95% CI: -4.6, 5.0 mmol/24-h) were nonsignificant. The correlation coefficients for the models were 0.303, 0.398, and 0.391, respectively, with the INTERSALT-adjusted and Zhejiang models showing superior performance at the population level., Conclusions: The 3 evaluation models may serve as effective, low-burden alternatives for assessing urinary sodium levels in the population. However, to enhance the accuracy and reliability of predictions at the individual level, further repeated measurements are necessary to minimize measurement errors and augment the validity of the estimations., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: The dietary habits and lifestyle changes during the COVID-19 pandemic could affect the urinary risk factors in kidney stone formers. In this study, we investigated the effects of the COVID-19 pandemic on 24-h urine metabolites, as a surrogate for dietary intake, in patients with kidney stones, in Tehran, Iran. Methods: We evaluated the medical records of all patients with urolithiasis who visited in our stone prevention clinic from the beginning of COVID-19 in Iran to 1 year later (Feb 2020–Feb 2021) and compared it with the patients' medical records in the same period a year before COVID-19 (Feb 2019–Feb 2020). Results: The results of our stone prevention clinic showed a decrease in the number of visits during COVID-19. Twenty-four-hour urine urea, sodium, and potassium were significantly lower, and 24-h urine magnesium was significantly higher during COVID-19. Higher 24-h urine oxalate was only shown in patients with the first-time visit, whereas lower 24-h urine uric acid and citrate were only shown in patients with the follow-up visits. Conclusions: COVID-19 pandemics may change some of the dietary habits of the patients, including lower salt, protein, and fruit and vegetable intake. Although economic issues, restricted access, or sanitation issues may be the reason for the undesirable dietary changes, the importance of a quality diet should be discussed with all patients, as possible. Since the number of patients visited in the stone clinic was lower during COVID-19, virtual visits could be an excellent alternative to motivate patients with kidney stones. [ABSTRACT FROM AUTHOR]

Abstract Background There is an increasing interest in finding less costly and burdensome alternatives to measuring population-level salt intake than 24-h urine collection, such as spot urine samples. However, little is known about their usefulness in developing countries like Fiji and Samoa. The purpose of this study was to evaluate the capacity of spot urine samples to estimate mean population salt intake in Fiji and Samoa. Methods The study involved secondary analyses of urine data from cross-sectional surveys conducted in Fiji and Samoa between 2012 and 2016. Mean salt intake was estimated from spot urine samples using six equations, and compared with the measured salt intake from 24-h urine samples. Differences and agreement between the two methods were examined through paired samples t-test, intraclass correlation coefficient analysis, and Bland-Altman plots and analyses. Results A total of 414 participants from Fiji and 725 participants from Samoa were included. Unweighted mean salt intake based on 24-h urine collection was 10.58 g/day (95% CI 9.95 to 11.22) in Fiji and 7.09 g/day (95% CI 6.83 to 7.36) in Samoa. In both samples, the INTERSALT equation with potassium produced the closest salt intake estimate to the 24-h urine (difference of − 0.92 g/day, 95% CI − 1.67 to − 0.18 in the Fiji sample and + 1.53 g/day, 95% CI 1.28 to 1.77 in the Samoa sample). The presence of proportional bias was evident for all equations except for the Kawasaki equation. Conclusion These data suggest that additional studies where both 24-h urine and spot urine samples are collected are needed to further assess whether methods based on spot urine samples can be confidently used to estimate mean population salt intake in Fiji and Samoa.

Abstract Background Proteinuria is known to be associated with both kidney function deterioration and cardiovascular diseases. While proteinuria estimation from 24-h urine samples has traditionally been considered as the standard method for assessment of the degree of urinary protein excretion, sample collection is associated with several technical problems such as inaccurate collection and the potential spread of drug-resistant pathogens. Therefore, the spot urine protein/creatinine ratio (PCR) assessment is currently recommended as an alternative. While the utility of PCR has been validated, studies on the association between spot urine PCR and 24-h proteinuria (24HP) in patients with chronic glomerular nephritis (CGN) and nephrotic syndrome (NS) are limited. This study aimed to evaluate whether an estimated result from a spot urine PCR could sufficiently approximate the daily urine protein excretion amount from a 24-h urine sample in patients with immunoglobulin A nephropathy (IgAN), minimal change disease (MCD), and membranous nephropathy– nephrotic syndrome (MN-NS). Methods The study participants included 161 patients with IgAN, MCD, or MGN-NS at the Jikei University Kashiwa Hospital and Kanagawa Prefecture Shiomidai Hospital. The correlation between spot urine PCR and a 24-h urine protein was investigated using linear regression analysis with Spearman’s correlation (r) coefficient and intraclass correlation coefficient (ICC). Results While high correlation coefficients (r = 0.86, P

Purpose of Review: The purpose of this review paper is to describe the 24-h urine collection in terms of its utility, collection process, and common problems with its acquisition. Recent Findings: Although 24-h urine collections are standard of care for high-risk stone formers, several nuances in test acquisition including inaccurate urine collections 50% of the time and poor patient compliance limit its potential utility. Compliance in obtaining 24-h urine collections has been shown to be improved in patients who have not undergone surgical treatment of urinary calculi, patients with metabolic stone disease or family history of stone disease, Caucasian ethnicity, and in those with more sedentary occupations. Studies show conflicting data of compliance regarding patient age and gender. Summary: Physicians must understand the difficulties regarding 24-h urine collections including patient compliance, variability between collections, and complexities with interpretation to best utilize this tool in guiding clinical management for the treatment of nephrolithiasis. [ABSTRACT FROM AUTHOR]

Background Developing approaches for the objective assessment of sugars intake in population research is crucial for generating reliable disease risk estimates, and evidence-based dietary guidelines. Twenty-four-hour urinary sucrose and fructose (24uSF) was developed as a predictive biomarker of total sugars intake based on 3 UK feeding studies, yet its performance as a biomarker of total sugars among US participants is unknown. Objectives To investigate the performance of 24uSF as a biomarker of sugars intake among US participants, and to characterize its use. Methods Ninety-eight participants, aged 18–70 y, consumed their usual diet under controlled conditions of a feeding study for 15 d, and collected 8 nonconsecutive 24-h urines measured for sucrose and fructose. Results A linear mixed model regressing log 24uSF biomarker on log total sugars intake along with other covariates explained 56% of the biomarker variance. Total sugars intake was the strongest predictor in the model (Marginal R2 = 0.52; P  <0.0001), followed by sex (P  = 0.0002) and log age (P  = 0.002). The equation was then inverted to solve for total sugars intake, thus generating a calibrated biomarker equation. Calibration of the biomarker produced mean biomarker-based log total sugars of 4.79 (SD = 0.59), which was similar to the observed log 15-d mean total sugars intake of 4.69 (0.35). The correlation between calibrated biomarker and usual total sugars intake was 0.59 for the calibrated biomarker based on a single biomarker measurement, and 0.76 based on 4 biomarker repeats spaced far apart. Conclusions In this controlled feeding study, total sugars intake was the main determinant of 24uSF confirming its utility as a biomarker of total sugars in this population. Next steps will include validation of stability assumptions of the biomarker calibration equation proposed here, which will allow its use as an instrument for dietary validation and measurement error correction in diet-disease association studies. [ABSTRACT FROM AUTHOR]

Objective: To develop an equation that can estimate the 24-h urinary Na excretion by using casual spot urine specimen for older hypertensive participants in rural Ningxia and further to compare with the INTERSALT method, Kawasaki method and Tanaka method.Design: Older hypertensive participants in rural Ningxia provided their casual spot urine samples and 24-h urine samples between January 2015 and February 2017. Sex-specific equation was developed using linear forward stepwise regression analysis. Model fit was assessed using adjusted R2. Approximately half of all participants were randomly selected to validate the equation. Mean differences, intraclass correlation coefficients and Bland-Altman plots were used to evaluate the performance of all methods.Setting: Pingluo County and Qingtongxia County in Ningxia Hui Autonomous Region, China.Participants: Older hypertensive participants in rural Ningxia.Results: Totally, 807 of 1120 invited participants provided qualified 24-h urine samples and spot urine samples. There was no statistical difference comparing the laboratory-based method against the new method and the INTERSALT method, while Kawasaki method had the largest bias with a mean difference of 40·81 g/d (95 % CI 39·27, 42·35 g/d). Bland-Altman plots showed similar pattern of the results.Conclusion: The INTERSALT method and the new equation have the potential to estimate the 24-h urinary Na excretion in this study population. However, the extrapolation of the results to other population needs to be careful. Future research is required to establish a more reliable method to estimate 24-h urinary Na excretion. [ABSTRACT FROM AUTHOR]

Background: Little is known about the capacity of overnight and spot urine samples to estimate changes in mean salt intake over time. The objective of this review was to compare the estimates of change in mean population salt intake based on 24-h urine and overnight/spot urine samples.Methods: Studies were systematically identified through searches of peer-reviewed databases (Medline, Embase, Global Health, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews) and grey literature. Studies that reported estimates of mean salt intake for at least two time points based on both 24-h and overnight/spot urines were deemed eligible. The capacity of overnight/spot urine samples to estimate the change in mean salt intake was assessed both at the individual-study level and overall through random-effects meta-analyses. The level of heterogeneity was assessed through the I2 statistic. Subgroup and sensitivity analyses were conducted to explore possible sources of heterogeneity, and check the robustness of the findings from the primary analysis.Results: A total of 1244 records were identified, 50 were assessed as full text, and 14 studies met the criteria, capturing data on 7291 participants from seven countries. Nine and five studies collected overnight and spot urines, respectively. The comparison of the change in mean salt intake between 24-h and overnight/spot urines showed some inconsistencies at the individual study-level. The pooled mean change in salt intake was - 0.43 g/day (95% CI - 1.16 to 0.30; I2 = 95%) using 24-h urines, and - 0.22 g/day (- 0.65 to 0.20; I2 = 87%) using overnight/spot urines, with a pooled difference-in-differences between the two methods of 0.27 g/day (- 0.23 to 0.77; I2 = 89%). Subgroup analyses showed substantial heterogeneity for most subgroups. Sensitivity analyses did not change the effect observed in the primary analysis.Conclusion: The evidence for the capacity of overnight/spot urines to estimate changes in mean salt intake over time is uncertain. More research where overnight/spot urines are collected in parallel with 24-h urines is needed to enable a more in-depth evaluation of these alternative approaches to estimating change in mean salt intake. [ABSTRACT FROM AUTHOR]

Globally, average dietary sodium intake is double the recommended amount, whereas potassium is often consumed in suboptimal amounts. High sodium diets are associated with increased cardiovascular and renal disease risk, while potassium may have protective properties. Consequently, patients at risk of cardiovascular and renal disease are urged to follow these recommendations, but dietary adherence is often low due to high sodium and low potassium content in processed foods. Adequate monitoring of intake is essential to guide dietary advice in clinical practice and can be used to investigate the relationship between intake and health outcomes. Daily sodium and potassium intake is often estimated with 24-h sodium and potassium excretion, but long-term balance studies demonstrate that this method lacks accuracy on an individual level. Dietary assessment tools and spot urine collections also exhibit poor performance when estimating individual sodium and potassium intake. Collection of multiple consecutive 24-h urines increases accuracy, but also patient burden. In this narrative review, we discuss current approaches to estimating dietary sodium and potassium intake. Additionally, we explore alternative methods that may improve test accuracy without increasing burden. [ABSTRACT FROM AUTHOR]

Graph: Figure 1: Measured gadolinium reference intervals for g Gd/g creatinine and g Gd/24 h and g Gd/g creatinine plotted against years of age of the donor. The triangles depict donor burdens for those not known to have been exposed to GBCAs, the diamonds depict burdens for donors for whom at least 1 year has passed since the last known GBCA exposure, and the squares depict donors who were last known to be exposed to GBCAs within the last 6-12 months. For comparison, this is still substantially lower than previously reported mean urinary concentrations of Gd of 214 g Gd/g creatinine at 10 days post GBCA administration and 22 g Gd/g creatinine at 30 days post GBCA administration [[7]]. [Extracted from the article]

The aim of this study was to determine the accuracy of the 24-h urine collection in preeclamptic pregnant women. This study included 65 singletons with preeclampsia and 53 singleton patients in a control-matched group. The ratio of inaccurate 24-h urine collection was measured by calculating expected urine creatinine excretion according to the proportion of pre-pregnancy weight and the lean body mass (LBM) of the patients. Comparisons were made between the accurately-collected 24-h urine protein excretion rates and the instant and 24-h urine protein/creatinine (P/Cr) and albumin/creatinine (A/Cr) ratios. Twenty-four-hour urine collection used to diagnose patients with preeclampsia was incorrectly collected 15-73.5% of the time among the patients and the control group. Instant and 24-h urine P/Cr and A/Cr ratios were correlated with total 24-h proteinuria among the patients in whom urine was collected correctly. Considering the 24-h urine P/Cr ratio, rather than the 24-h urine protein excretion value, is a better way to diagnose preeclampsia. IMPACT STATEMENT What is already known on this subject? Twenty-four-hour urine collection is considered as the gold standard of diagnosing proteinuria in preeclampsia, in case of the correctly collected. What do the results of this study add? Generally, in the literature the correctness of 24-h proteinuria is not questioned. However, it is actually quite important in daily practice to make the correct diagnosis of the proteinuria not to misdiagnose preeclampsia. What are the implications of these findings for clinical practice and/or further research? In this article, we aimed to show the importance of accurately collected 24-h urine in preeclampsia. We consider and advise to change the gold standard of this technique to 24-h protein/creatinine (P/Cr) ratio, in order to make correct diagnosis of the preeclampsia. [ABSTRACT FROM AUTHOR]

Background: Measurement of multiple food intake exposure biomarkers in urine may offer an objective method for monitoring diet. The potential of spot and cumulative urine samples that have reduced burden on participants as replacements for 24-h urine collections has not been evaluated.Objective: The aim of this study was to determine the utility of spot and cumulative urine samples for classifying the metabolic profiles of people according to dietary intake when compared with 24-h urine collections in a controlled dietary intervention study.Methods: Nineteen healthy individuals (10 male, 9 female, aged 21-65 y, BMI 20-35 kg/m2) each consumed 4 distinctly different diets, each for 1 wk. Spot urine samples were collected ∼2 h post meals on 3 intervention days/wk. Cumulative urine samples were collected daily over 3 separate temporal periods. A 24-h urine collection was created by combining the 3 cumulative urine samples. Urine samples were analyzed with metabolite fingerprinting by both high-resolution flow infusion electrospray mass spectrometry (FIE-HRMS) and proton nuclear magnetic resonance spectroscopy (1H-NMR). Concentrations of dietary intake biomarkers were measured with liquid chromatography triple quadrupole mass spectrometry and by integration of 1H-NMR data.Results: Cross-validation modeling with 1H-NMR and FIE-HRMS data demonstrated the power of spot and cumulative urine samples in predicting dietary patterns in 24-h urine collections. Particularly, there was no significant loss of information when post-dinner (PD) spot or overnight cumulative samples were substituted for 24-h urine collections (classification accuracies of 0.891 and 0.938, respectively). Quantitative analysis of urine samples also demonstrated the relation between PD spot samples and 24-h urines for dietary exposure biomarkers.Conclusions: We conclude that PD spot urine samples are suitable replacements for 24-h urine collections. Alternatively, cumulative samples collected overnight predict similarly to 24-h urine samples and have a lower collection burden for participants. [ABSTRACT FROM AUTHOR]

Background There is growing interest in assessing a population's prevalence of inadequate nutrient intake using biomarkers. However, within-person variation is generally ignored because repeated data collections are considered costly and burdensome. Objectives The study aimed to show the importance of estimating, from repeated 24-h urine collections, a population's habitual salt intake and to explore the potential of using the ratio of within-person variance to total variance from an external source (W:T variance) with single 24-h urine collection. Methods Salt intake was predicted from data for 24-h urinary sodium excretion in adult kidney transplant recipients in 1992–1997 (n  = 432) and 2006–2011 (n  = 1159). The salt intake distribution of single-day measurements was compared with estimates from multiple 24-h urine collections, which were statistically corrected for within-person variance. Habitual salt intake was also estimated using single-day measurements and external variance estimates. From each distribution, the proportion below specified cut-off values was estimated. Results In 2006–2011 the average habitual salt intake was 10.6 g/d (men) and 8.5 g/d (women); in 1992–1997 these values were 8.6 g/d and 7.5 g/d, respectively. The proportion with salt intake <6 g/d was 5% and 13% in 2006–2011 and 22% and 28% in 1992–1997, respectively, for men and women. Correction for within-person variance significantly narrowed the salt intake distribution—the proportion with salt intake <6 g/d was overestimated by 3–13 percentage points using single-day data. Sensitivity analyses showed the importance of a sufficient sample size for estimating variance components. Variation of the W:T variance showed up to 40 percentage points deviation in the proportion with intakes below a specified cut-off value. Conclusions To estimate a population's salt intake distribution, it is important to correct 24-h urinary sodium excretion for within-person variance. Predicting habitual salt intake distribution using single-day measurements with external variances is promising; a sensitivity analysis is recommended to show the effect of different external variances. [ABSTRACT FROM AUTHOR]

To document trends in human exposure to environmental pollutants, the German Environmental Specimen Bank (ESB) has been routinely collecting and archiving 24-h urine samples from young adults at four sampling sites in Germany on an annual basis. For the purpose of normalizing measured analyte concentrations, urinary creatinine (UC), specific gravity (SG), conductivity (CON), and total urine volume (UVtot) of 24-h urine samples have also been recorded. These parameters are however susceptible to variation over time, as well as within/among participants and normalization against them can thus affect the interpretation of data regarding exposure to environmental pollutants. To evaluate the influence of normalization against these parameters, we first sought to determine variations of these parameters with regard to differences between sexes and trends over time. We analysed data from 8619 urine samples collected from 1997 to 2016. We observed an inverse relation between UVtot and UC, SG, and CON. We also found differences between sexes for UC, SG and CON, but not UVtot. UC, SG, and CON showed significant decreasing trends over time in both sexes. In contrast, a significant increase of over 30% in UVtot, independent of participant age and BMI, was revealed. This increase in UVtot and the concomitant sample dilution is likely to have an impact on measured analyte concentrations in 24-h urine samples. Hence, normalization of urinary concentrations is warranted when interpreting time trends of human exposure. Next, urinary calcium (Ca2+) concentrations of ESB participants were used to demonstrate the effects of normalization against each of the four urine parameters. From 1997 to 2016, measured Ca2+ concentrations showed a statistically significant but scientifically implausible decrease. Normalization of Ca2+ concentrations against UVtot (by calculating the total daily excretion), UC, or CON, but not SG, eliminated this decrease. Consistent with previous work, Ca2+ concentrations in urine and total daily Ca2+ excretion were higher for males than females. Normalization against UC, SG, or CON, however, attenuated this difference. Thus, to avoid misinterpretation in trend analysis and sex-specific excretion in 24-h urine samples, the calculation of the total daily excretion is recommended. [ABSTRACT FROM AUTHOR]

Purpose: There are epidemiologic studies indicating a positive correlation between high sodium and low potassium intake and body mass index. Therefore, this study was conducted in a cross-sectional sample of Iranian children and adolescents to evaluate the link between 24-h urinary Na:K ratio and risk of obesity. Methods: In this cross-sectional study, 374 participants aged 11–18 years were included. One 24-h urine sample was collected by each participant to estimate Na:K ratio. Anthropometric measurements were carried out and overweight/obesity was defined as a BMI ≥ 85th percentile and abdominal obesity as a waist:height ratio (WHtR) of more than 0.5. Results: As expected, 24-h urinary Na:K ratio showed significant associations with risk of overweight/obesity. Risk of adiposity assessed by WC and PBF was significantly associated with Na:K ratio after adjusting for SSBs consumption and calorie intake. Urinary Na:K ratio showed significant association with risk of adiposity assessed by WC only in girls in the highest tertile group with OR of 2.71 (95% CI 1.14–6.43), only after the addition of calorie intake. Adiposity assessed by PBF was only associated with Na:K ratio among boys with OR of 4.47 (95% CI 1.44–9.87) and 3.87 (95% CI 1.20–8.48), after adjusting for SSBs consumption and calorie intake, respectively. Conclusion: Our findings suggest that reducing Na and increasing K intake could be used as a useful approach to lower the risk of obesity and associated burden of disease in Iran. However, more studies are warranted. [ABSTRACT FROM AUTHOR]

Objective: To determine the necessity for acid-washed containers for 24-h urine copper analysis.Methods: Copper solutions, with concentrations relevant to clinical decision limits, were prepared by spiking both assay diluent and unknown urine samples with the copper calibrator. Samples were split between plain and acid-washed 24-h urine containers, and copper analysis was performed using inductively coupled mass spectrometry (ICP-MS).Results: Measurement of copper in both spiked diluent and spiked urine samples showed minimal concentration bias between acid-washed and plain 24-h urine containers.Conclusions: Acid-washed containers are not required for the measurement of copper in 24-h urine samples. [ABSTRACT FROM AUTHOR]

Background: The capacity of spot urine samples for detecting changes in population sodium and potassium excretion is unclear.Methods: Changes in urinary sodium and potassium excretion, over a 6-month to 2-year interval, were measured from 24-h urine samples and estimated from spot urine samples using several published methods in 3270 Chinese. Additional estimates were made by multiplying individual spot sodium and potassium concentrations by a single estimated 24-h urine volume derived from external data.Results: The measured difference in 24-h urinary excretion between intervention and control groups was -0.35 g (95% CI: -0.68 to -0.02; P = 0.039) for sodium and 0.66 g (95% CI: 0.52 to 0.80; P < 0.001) for potassium, based upon 24-h urine samples. The corresponding estimates of sodium differences for the Tanaka (-0.06 g), Kawasaki (-0.09 g), Intersalt without potassium (-0.09 g) and Intersalt with potassium (-0.14 g) equations were all smaller and identified no reduction in sodium excretion (all P > 0.10). The estimates were -0.65 g for sodium and 1.11 g for potassium using individual spot urine concentrations and an externally derived standard urine volume (both P < 0.01).Conclusions: The published equations were unable to detect the differences in sodium excretion measured by 24-h urine samples. A method based upon spot urine electrolyte concentrations and a standard urine volume may offer an alternative approach to measuring differences in sodium and potassium excretion between population groups without requiring 24-h urine, but will need further investigation. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to establish reference intervals for 24-h urinary stone risk factors in the healthy Chinese Han population. Methods: From May 2013 to July 2014, we collected and analyzed 24-h urine samples from healthy adult Han population during a cross-sectional study across China. The protocol for analysis of 24-h urine included volume, pH, oxalate, citrate, sodium, potassium, chloride, calcium, phosphorous, creatinine, urate, magnesium, the ion activity products of calcium oxalate (AP(CaOx) indexs) and calcium phosphate (AP(CaP) indexs). We calculated the reference intervals according to the Clinical and Laboratory Standards Institute (CLSI) 2008 guidelines and compared them with those recorded in other studies. Results: A total of 132 male and 123 female healthy subjects with a mean (SD, range) age of 52.4 (15.2, 19-89) years were eligible in the final analysis. Men had higher 24-h excretion of creatinine, calcium, urate and phosphorus and lower levels of citrate, magnesium, chloride, sodium and potassium than women. AP(CaOx) indexs and AP(CaP) indexs were significantly higher among men than women. When urinary findings were compared with the reference intervals, most of our data showed a high abnormality rate, especially for creatinine, calcium, citrate, magnesium, chloride, sodium and potassium. Conclusions: The present study revealed the normal metabolic status for stone risk factors of the Chinese Han population. It is therefore necessary for each country or region to define their own reference intervals for comparison of stone risk factors between patients and healthy subjects. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

Objective: To investigate the impact of green tea on urinary oxalate excretion in healthy male volunteers. Materials and methods: The oxalate concentrations after different brewing times (2-60 min) of different qualities (2-8 g) of green tea were measured in in vitro experiment. In in vivo experiment, the effects on urine composition were assessed in 12 healthy men with an age of 24-29 years. Each subject was requested to collect two 24-h urine samples under normal dietary conditions. Green tea prepared from tea bags containing 2 g of tea leafs was consumed by the subjects for 7 consecutive days, and 24-h urine samples were collected and analyzed on days 6 and 7. After 3-week washout interval, all subjects consumed green tea containing 4 g of leaf tea for another 7 consecutive days. Two 24-h urine samples were collected on the last 2 days. Urine volume, pH, calcium, magnesium, sodium, phosphate, potassium, chloride, citrate, oxalate, urate and creatinine were measured. Results: In the in vitro experiments, oxalate in solution increased with brewing time ( p < 0.05) and tea quality ( p < 0.05). In the in vivo experiment, 24-h urinary oxalate increased significantly (0.24 ± 0.09 mmol to 0.32 ± 0.13 mmol, p = 0.045) when tea was prepared from 2-g bags of green leaf tea. Consumption of green tea containing 4 g of leaf tea resulted in 24-h urinary oxalate increase (0.25 ± 0.25 mmol to 0.34 ± 0.22 mmol, p = 0.041). Conclusions: In vitro studies showed that there was a gradual increase in solution concentrations of oxalate that was associated with increased brewing time and increased quality of green tea. Studies in normal men showed that green tea consumption was associated with increased urinary exertion of oxalate. [ABSTRACT FROM AUTHOR]

Sodium, potassium, calcium, magnesium, zinc, copper and iron are associated with the sequela of hypertension. The most reliable method for testing those elements is by collecting 24-h urine samples. However, this is cumbersome and collection of spot urine is more convenient in some circumstance. The aim of this study was to compare the concentrations of different elements in 24-h urine and spot urine. Methods Data was collected from a sub-study of China Salt Substitute and Stroke Study. 240 participants were recruited randomly from 12 villages in two counties in Ningxia, China. Both spot and 24-h urine specimens were collected from each patient. Routine urine test was conducted, and concentration of elements was measured using microwave digestion and Inductively Coupled Plasma-Optical Emission Spectrometry. Partial correlation analysis and Spearman correlation analysis were used to investigate the concentration of different elements and the relationship between 24- h urine and spot urine. Results A partial correlation in sodium, potassium, calcium, magnesium and iron was found between paired 24-h urine and spot urine samples except copper and zinc: 0.430, 0.426, 0.550, 0.221 and 0.191 respectively. Conclusions Spot urine can replace 24-h urine for estimating some of the elements in hypertensive patients with normal renal function. [ABSTRACT FROM AUTHOR]

Background: Association between casual and 24-h urinary sodium-to-potassium (Na/K) ratio is well recognized, although it has not been validated in diverse demographic groups. Our aim was to assess utility across and within populations of casual urine to estimate 24-h urinary Na/K ratio using data from the INTERSALT Study.Methods: The INTERSALT Study collected cross-sectional standardized data on casual urinary sodium and potassium and also on timed 24-h urinary sodium and potassium for 10 065 individuals from 52 population samples in 32 countries (1985-87). Pearson correlation coefficients and agreement were computed for Na/K ratio of casual urine against 24-h urinary Na/K ratio both at population and individual levels.Results: Pearson correlation coefficients relating means of 24-h urine and casual urine Na/K ratio were r = 0.96 and r = 0.69 in analyses across populations and individuals, respectively. Correlations of casual urine Na/creatinine and K/creatinine ratios with 24-h urinary Na and K excretion, respectively, were lower than correlation of casual and 24-h urinary Na/K ratio in analyses across populations and individuals. The bias estimate with the Bland-Altman method, defined as the difference between Na/K ratio of 24-h urine and casual urine, was approximately 0.4 across both populations and individuals. Spread around, the mean bias was higher for individuals than populations.Conclusion: With appropriate bias correction, casual urine Na/K ratio may be a useful, low-burden alternative method to 24-h urine for estimation of population urinary Na/K ratio. It may also be applicable for assessment of the urinary Na/K ratio of individuals, with use of repeated measurements to reduce measurement error and increase precision. [ABSTRACT FROM AUTHOR]

Purpose: It is often reported that Na intake levels are higher in Japan than in western countries. Detailed analysis of food intake and its association with Na intake are necessary for supporting further decreases in Na consumption in Japan. We investigated the association between Na and food intake by food group using data from the Japanese participants of the INTERMAP Study. Method: Results from the Japanese participants of the INTERMAP Study who did not use antihypertensive medication and/or consume a reduced Na diet were used (531 men and 518 women, aged 40-59 years), obtained from four 24-h dietary recalls and two 24-h urine collections from each participant. We developed a classification system with 46 food group classifications; food consumption and Na intake from these groups were compared across quartiles of participants determined by 24-h urinary Na excretion per unit of body weight (UNa/BW). Results: Average daily Na intake from Japanese high-Na foods was 2552 mg/day. Participants with a higher UNa/BW consumed a significantly greater amount of high-Na Japanese foods, such as salted fish ( P = 0.001) and miso soup ( P < 0.001). They also had greater amount of rice ( P = 0.001). Participants with lower UNa/BW consumed a significantly greater amount of western foods, such as bread ( P < 0.001) and milk and dairy products ( P < 0.001). Conclusions: Detailed analyses of various Japanese and western food intakes in addition to Na intake were performed. These results can be used to help draw up effective programs for the reduction in Na intake and prevention of prehypertension/hypertension in the Japanese population. [ABSTRACT FROM AUTHOR]

Purpose: A biomarker for dietary flavonoid intake from fruit and vegetables (FlavFV) is needed to elucidate the relevance of flavonoids from these sources for the prevention of chronic diseases. Urinary hippuric acid (HA)-a major metabolite of flavonoids-is promising in this respect as it was shown to satisfyingly indicate fruit and vegetable consumption in different age groups. Therefore, we validated urinary HA as a biomarker for intake of FlavFV. Methods: Analyses included data from 287 healthy adolescents of the DONALD Study (aged 9-16 years) for whom a minimum of two pairs of HA measurements from 24-h urine samples (test method) and FlavFV intake estimated from 3-day weighed dietary records (reference method) existed. Agreement between both methods was assessed by Spearman correlation and cross-classification analyses. Possible confounders of the association were identified by linear regression models. Analyses were performed using a split-sample approach allowing for consecutive exploration ( n = 192) and confirmation ( n = 95) of results. Results: Agreement between urinary HA excretion and FlavFV intake was moderate according to correlation analysis in the exploratory sample ( r = 0.47, P < 0.0001). Yet, 79 % of the subjects were classified into same/adjacent quartiles, and only 5 % were misclassified into opposite quartiles. These findings were corroborated by analyses in the confirmatory sample ( r = 0.64; 88 % in same/adjacent vs. 4 % in opposite quartiles). Body surface area (BSA) was the only relevant covariate in the exploratory sample, and its adjustment improved cross-classification estimates in both subsamples. Conclusions: BSA-adjusted 24-h urinary HA excretion represents a suitable biomarker of habitual FlavFV intake in healthy adolescents. [ABSTRACT FROM AUTHOR]