Development and validation of a prediction model for estimating 24-Hour Urinary Sodium Excretion using spot urine samples in adult patients.

The measurement of urinary sodium excretion provides valuable information about an individual's sodium balance and can help in the management of various medical conditions. However, the collection of 24-hour urine samples is subject to errors. Spot urine sodium (uNa) measurements are a reliable alternative to 24-hour urine collections for estimating urinary sodium excretion. OBJECTIVE: To assess whether 24-h urinary sodium excretion (24uNa) can be estimated from spot samples in adult patients who attend hospital clinics. DESIGN: Methods: A cross-sectional study with a development (284 patients) and a validation cohort (229 patients) was conducted at our hospital. A multivariate linear regression model was built which was compared with former models. Concordance analyses and comparison of the ability to correctly classify each patient against a prespecified uNa cut-off value of 130 mmol/24h were performed, assessed by the C-statistic. RESULTS: The model was well calibrated (slope [95%CI] in internal validation: 0.965 [0.947-0.987], showing good discrimination, and performed robustly in an external validation cohort (slope: 0.811 [0.675-0.946]). The mean bias between the measured and the estimated 24uNa by NaRYC was 24.85 mmol/24h [17.06-32.63]. The NaRYC had the highest values of Pearson coefficient (0.613 p<0.0001), accuracy (P30): 56.8%, and AUC-ROC: 0.822 [0.766-0.869] as compared to other seven equations. CONCLUSION: Although the mean bias of the results is quite acceptable, the variability observed in the 95%CI makes not recommend the general use of a spot as a substitute of the 24-hour urine in order to estimate the total urine excretion of Na in a single subject basis.

Reliability of the spot urine protein/creatinine ratio for assessing proteinuria in patients with renal disease.

OBJECTIVE: This study aimed to assess the reliability of the spot urine protein/creatinine (sP/Cr) ratio for evaluating proteinuria across different ranges and renal functions. METHODS: In this retrospective study, we analyzed 24-hour urine protein excretion (24 h UP) and sP/Cr measurements in 216 patients with renal disease. Pearson correlation and Bland-Altman analyses were performed to evaluate the correlation and agreement between 24 h UP and the sP/Cr. RESULTS: The patients were categorized into the following three 24 h UP groups: 150 to 299 mg/24 hours, 300 to 3499 mg/24 hours, and >3500 mg/24 hours. Significant positive correlations were found between the sP/Cr and the first two 24 h UP groups (r = 0.9104 and r = 0.9721, respectively) but not between the third group (r = 0.3110). Bland-Altman analysis confirmed good agreement in the group with <3500 mg/day proteinuria. Estimated glomerular filtration rates ≥60 mL/minute and <60 mL/minute were significantly correlated with the sP/Cr (r = 0.8714 and r = 0.4516, respectively). CONCLUSION: The sP/Cr ratio is a reliable indicator for non-nephrotic proteinuria, irrespective of renal function, but is unreliable for nephrotic-range proteinuria.

Intake and excretion of cadmium of Japanese adult.

OBJECTIVE: It is the aim of this study if the recent Cd intake and excretion is consistent with the regression equation proposed by Ikeda et al. (Environ. Health Prev. Med. 20 (2015) 455-459) which utilized intake/excretion data of 3 decades ago METHOD: Matched duplicate diet and spot urine samples were collected in 2017-2019 from 150 Japanese adults (85 females and 65 males, mean age being 44.9) for the estimation of daily Cd intake and urinary excretion. Cd concentration in diet and urine was measured by ICP mass spectrometry. RESULT: Geometric mean (geometric standard deviation) of Cd intake was 12.1 (1.67) µg/person/day or 0.206 (1.66) µg/kg body wt./day. Urinary Cd concentration was 0.54 (2.6) µg/g creatinine or 0.67 µg/L (2.3) (gravimetric correction). These were lower than those reported previously for Japanese populations. Urinary concentration was significantly higher in females than in males for both creatinine and gravimetric corrections. Dietary intake was higher in males than in females but this difference diminished after body weight correction. There was no significant correlation between Cd intake and urinary concentration on individual basis, which was expected because urinary Cd concentration reflects Cd body burden but not recent intake level. Meanwhile, the geometric mean intake and urine concentration was consistent with the regression equation proposed by Ikeda et al., which was based on intake and excretion surveys for 30 non-exposed Japanese female populations. CONCLUSION: This result supported that the regression equation of Ikeda et al. could be used for conversion of urinary Cd excretion level of a population to intake level.

Comparison Between Twenty-Four-Hour Collection and Single Spot Urines for the Detection of Biogenic Amines by High-Performance Liquid Chromatography Tandem Mass Spectrometry.

Background: Pheochromocytomas and paragangliomas (PPGL) are neuroendocrine tumors that originate from adrenal medulla or extra-adrenal chromaffin cells, respectively. They produce an excess of catecholamines and their metabolites. Abnormal levels of these biomolecules have been also found in pediatric patients with neuroblastoma (NB). Due to the diurnal fluctuation, the laboratory practice recommends the determination of biogenic amines in acidified 24-h urine samples. However, the collection and acidification of specimens cannot be performed easily, especially for children. Spot urines represent an attractive alternative for the detection of catecholamines and corresponding metabolites. Methods: In our study, we enrolled 50 patients with symptoms related to PPGL and we determined the concentration values for both spot and 24-h urine samples using high-performance liquid chromatography tandem mass spectrometry (HPLC/MS-MS). Since day variations of the urinary concentration are due to fluctuations in renal excretion rather than in production, we normalized the concentration of biogenic amines in spot urine and in 24-h urine collection to urinary creatinine concentration. A correlation study between the normalized levels of biogenic amines was performed using a linear regression analysis model and Pearson's correlation coefficients. Results: We obtained a good correlation of values which suggests an interchangeability of the 24-h and random urine samples. Only for epinephrine a weak correlation was determined. Conclusions: Our findings suggest that the sample collection as single spot urine may replace 24-h collection for the detection of urinary biogenic amines by HPLC/MS-MS.

Association between spot urinary sodium-to-potassium ratio and blood pressure among Chinese adults aged 18-69 years: the SMASH study.

Background: Excessive sodium and low potassium intake are involved in the development of hypertension. Growing evidence showed that the sodium-to-potassium ratio (Na/K) was significantly associated with blood pressure (BP). However, studies on the dose-response relationship of spot urinary Na/K ratio with hypertension and BP in the general population are scarce, especially in the Chinese population. Materials and methods: Data from the post-intervention survey of the Shandong Ministry of Health Action on Salt and Hypertension (SMASH) project was analyzed. Associations between Na/K molar ratio and hypertension prevalence and between Na/K molar ratio and BP indices were analyzed using multivariable logistic and linear regression, respectively, followed by subgroup analysis and interaction analysis. The restricted cubic spline model was used to explore the dose-response relationship. Informed by existing literature, we adjusted for potential confounding factors, including temperature and renal function, to assess the association and dose-response relationship. Results: There was a non-linear positive association between Na/K and hypertension (OR:1.09, 95%CI: 1.08-1.11) and a linear positive association between Na/K and systolic BP, diastolic BP, and mean arterial pressure (ß 0.53, 95%CI: 0.45-0.60; ß 0.36, 95%CI: 0.31-0.41; and ß 0.42, 95%CI: 0.36-0.47, respectively). The association was stronger in individuals with hypertension, female patients, those in the 50-59-year age group, and those who were obese. Environmental temperatures had little impact on associations. Conclusion: Our findings provide further evidence that the spot urinary Na/K ratio is a simple, useful, and convenient indicator for monitoring salt reduction and potassium increase, which could be used in clinical and public health practices.

Spot urinary sodium in CKD patients: correlation with 24h-excretion and evaluation of commonly used prediction equations.

BACKGROUND: Salt intake in CKD patients can affect cardiovascular risk and kidney disease progression. Twenty-four hour (24h) urine collections are often used to investigate salt metabolism but are cumbersome to perform. We assessed urinary sodium (U-Na) concentration in spot urine samples and investigated the correlation with 24h U-Na excretion and concentration in CKD patients under nephrological care. Further, we studied the role of CKD stage and diuretics and evaluated the performance of commonly used formulas for the prediction of 24h U-Na excretion from spot urine samples. METHODS: One hundred eight patients of the German Chronic Kidney Disease (GCKD) study were included. Each participant collected a 24h urine and two spot urine samples within the same period. The first spot urine sample (AM) was part of the second morning urine. The second urine sample was collected before dinner (PM). Patients were advised to take their medication as usual without changing dietary habits. U-Na concentrations in the two spot urine samples and their average ((AM + PM)/2) were correlated with U-Na concentration and total Na excretion in the 24h urine collections. Correlations were subsequently studied after stratification by CKD stage and diuretic intake. The usefulness of three commonly applied equations to estimate 24h U-Na excretion from spot urine samples (Kawasaki, Tanaka and Intersalt) was determined using Bland-Altman plots, analyses of sensitivity, specificity, as well as positive (PPV) and negative predictive values (NPV). RESULTS: Participants (42 women, 66 men) were on average (± SD) 62.2 (± 11.9) years old, with a mean serum creatinine of 1.6 (± 0.5) mg/dl. 95% had arterial hypertension, 37% diabetes mellitus and 55% were on diuretics. The best correlation with 24h U-Na total excretion was found for the PM spot U-Na sample. We also found strong correlations when comparing spot and 24h urine U-Na concentration. Correction of spot U-Na for U-creatinine did not improve strength of correlations. Neither CKD stage, nor intake of diuretics had significant impact on these correlations. All examined formulas revealed a significant mean bias. The lowest mean bias and the strongest correlation between estimated and measured U-Na excretion in 24h were obtained using the Tanaka-formula. Also, application of the Tanaka-formula with PM U-Na provided best sensitivity, specificity, PPV and NPV to estimate U-Na excretion > 4g/d corresponding to a salt consumption > 10g/d. CONCLUSION: U-Na concentration of spot urine samples correlated with 24h U-Na excretion especially when PM spot U-Na was used. However, correlation coefficients were relatively low. Neither CKD stage nor intake of diuretics appeared to have an influence on these correlations. There was a significant bias for all tested formulas with the Tanaka-formula providing the strongest correlation with measured 24h U-Na excretion. In summary, using spot urine samples together with the Tanaka-formula in epidemiological studies appears feasible to determine associations between approximate salt intake and outcomes in CKD patients. However, the usefulness of spot-urine samples to guide and monitor salt consumption in individual patients remains limited.

Assessing Sodium Intake in Middle-Aged and Older Adults with Elevated Blood Pressure: Validation of Spot Urine Excretion and Dietary Survey-Derived Estimates.

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.

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

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

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

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

Comparison of body iodine pool assessment methods before radioiodine therapy.

INTRODUCTION AND OBJECTIVES: Radioactive iodine therapy (RAIT) is recommended to reduce the risk of recurrence and metastasis in patients with intermediate-high risk differentiated thyroid cancer (DTC). In preparation for RAIT, stimulation of thyroid-stimulating hormone and reduction of body iodine pool are important for treatment success. For this purpose, patients are asked to reduce their iodine intake before RAIT, and the body iodine pool can be evaluated by measuring iodine excretion in urine before treatment. The aim of our study is to compare the methods used to measure the body iodine pool in the evaluation of the restricted iodine diet (RID) effectiveness applied in the RAIT preparation. PATIENTS AND METHODS: Eighty DTC patients discontinued levothyroxine three weeks before RAIT and followed up with a RID two weeks before treatment. After two weeks of RID, all patients collected their 24-h urine the day before the RAIT date. Patients completed 24-h urine samples on the morning of the RAIT date and also provided a spot urine sample. The estimated 24-h creatinine excretion of the patients was calculated. Estimated 24-h urinary iodine excretion (UIE) was calculated using the spot urine iodine/creatinine (I/C) ratio of the patients. 24-h UIE, iodine concentration in spot urine, I/C ratios in spot urine and estimated 24-h UIE of the patients were analyzed by comparing with each other. RESULTS: In 99% of the patients, RID efficiency was sufficient according to 24-h UIE before RAIT. The mean 24-h UIE was 48.81 micrograms/day (mcg/day) in 24-h urine samples taken from the patients to evaluate the body iodine pool. The patients' iodine concentrations in spot urine, I/C ratios in spot urine, and estimated 24-h UIE were all statistically significantly lower than actual 24-h UIE, which was the reference method (p: 0.026 vs <0.001 vs 0.041). Moderate positive correlation between 24-h UIE and iodine concentration in spot urine (r: 0.440), I/C ratio in spot urine (r: 0.493), and estimated 24-h UIE (r: 0.560) found. The strongest correlation was obtained with the estimated 24-h UIE. CONCLUSION: The estimated 24-h UIE obtained by using the I/C ratio in spot urine can be used practically and safely as an alternative to UIE in 24-h urine, which is the gold standard method for evaluating body iodine pool.

Associations between estimation of salt intake and salt-restriction spoons and hypertension status in patients with poorly controlled hypertension: a community-based study from Huzhou City, Eastern China.

BACKGROUND: As the prevalence of hypertension increases in China, it is advised to use salt-restriction spoons (SRS) as a lifestyle modification. This study aimed to examine the associations between estimated salt consumption, SRS usage, and the hypertension status in individuals with poorly controlled hypertension. METHODS: Data was collected in Huzhou City, Zhejiang Province, in 2021 using convenience sampling. The analysis involved ordinal logistic regression and restricted cubic splines to assess the relevant factors. RESULTS: The study found that 73.34% of the 1215 patients had uncontrolled blood pressure (BP). Urinary excretion was assessed through the utilization of the Kawasaki, INTERSALT, and Tanaka formulas. The outcomes of these three methodologies revealed average daily sodium excretion values of 208.70 (65.65), 154.78 (33.91), and 162.61 (40.87) mmol, respectively. The prevalence of utilizing SRS was found to be 37.78% in this study. Despite the acknowledgment among SRS users of the potential hazards associated with excessive salt consumption, there exists a contradictory pattern of attitudes and behaviors concerning salt reduction. Among individuals with different levels of salt intake (quartiles 1-4, Q1 vs Q4), there was a positive association between limiting salt and hypertension status when controlling for other variables (Kawasaki adjusted OR = 0.58, 95% CI = 0.43-0.79; INTERSALT adjusted OR = 0.62, 95% CI = 0.41-0.92; Tanaka adjusted OR = 0.61, 95% CI = 0.45-0.92, p < 0.05). Our research also revealed that using or used SRS was a protective factor for blood BP control (adjusted OR = 0.79, 95% CI = 0.64-0.99, P < 0.05). The restricted cubic spline plots illustrated a monotonic upward relationship between estimated 24-h urinary Na and BP (P-overall association < 0.05; P-non-linear association > 0.05). CONCLUSIONS: The use of dietary SRS could result in decrease in daily salt intake for BP control in patients with poorly controlled hypertension. To reduce the impact of high BP in China, additional studies are required to create interventions that can enhance the results for patients.

Association between sodium-to-potassium ratio in spot urine and hospitalization due to heart failure in high-risk Japanese patients.

Background: In Japanese cardiovascular (CV) high-risk patients, the ESPRIT (Evaluation of Sodium Intake for the Prediction of Cardiovascular Events in Japanese High-risk Patients) study showed that high sodium excretion (≥4.0 g/day) was associated with a composite CV events of heart failure (HF) hospitalization, acute coronary syndrome, cerebrovascular events, and CV deaths. In this context, the sodium-to-creatinine (Na/Cr) ratio in spot urine was found to be significantly associated with HF hospitalizations. Since a stable potassium balance plays a particularly relevant role for CV patients, this post-hoc study was designed to investigate the extent to which consideration of the sodium-to-potassium (Na/K) ratio represents a better predictor of HF hospitalizations in the ESPRIT study population. Methods: This is a post-hoc analysis of a previously reported ESPRIT study (n = 520, 60 HF hospitalizations). Results: Receiver operating curve analysis yielded optimal Na/K ratio cut-off value of 2.9 for detecting HF hospitalization. Kaplan-Meier curve showed that high Na/K ratio in spot urine was associated with increased HF hospitalization (p < 0.001). Cox proportional hazards model analysis revealed that high Na/K ratio was associated with HF hospitalization with a hazard ratio of 2.97 (confidence interval: 1.67-5.61). An association between high Na/K ratio and HF hospitalization remained after adjustments for Na/Cr ratio in spot urine or the use of diuretics. Conclusion: The Na/K ratio in spot urine is associated with HF hospitalization in high-risk Japanese patients.

Mid-Trimester Spot Urinary Albumin/Creatinine Ratio as a Screening Tool in Prediction of Pre-eclampsia.

Aims and Objectives: To determine utilization of spot urinary albumin/creatinine ratio (UACR) to predict subsequent development of preeclampsia, measured between 17 and 24 weeks of gestational age in asymptomatic antenatal woman and determine their maternal and neonatal outcomes. Introduction: In preeclampsia the basic pathology is generalized endothelial dysfunction. It causes glomerular endotheliosis which leads to proteinuria, decreased glomerular filtration rate and renal blood flow. Thus microalbuminuria is an early marker which can measured to predict preeclampsia. Materials and Methods: It is a prospective observational study, carried out for one year in a cohort of asymptomatic antenatal women at 17-24 weeks of gestational age, attending hospital for routine antenatal check-up with a singleton pregnancy and no associated complications. Urine albumin and creatinine ratio (UACR) is measured at first visit, and women were followed till delivery and the maternal and foetal outcomes were recorded. Results: Out of 81 pregnant women enrolled in the study, 58% belonged to 18-25 years, 54.3% belonged to lower middle class. There was a significant difference in mean UACR among women who developed preeclampsia (PE) and gestational diabetes mellitus (GDM) with p value < 0.05. In the study there was significant association between severe PE, PE and GDM with UACR at 22 as cut-off, with p value < 0.05. In the study among those with UACR > 22, 2.5% had IUFD, 12.5% had LBW, and 7.5% were admitted to NICU. Conclusion: With the measurement of spot UACR in mid-trimester we can predict the development of preeclampsia before the onset of clinical manifestations. UACR > = 171 mg/g predicted preeclampsia well before the onset of clinical manifestations with high sensitivity of 83.3% and specificity of 98.6%. Supplementary Information: The online version contains supplementary material available at 10.1007/s13224-023-01862-9.

Salt Intake Estimation from Urine Samples in South Asian Population: Scoping Review.

The World Health Organization recommended reducing one's salt intake below 5 g/day to prevent disability and death from cardiovascular and other chronic diseases. This review aimed to identify salt estimation at the population level in South Asian countries, namely Afghanistan, Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka. We searched electronic databases and government websites for the literature and reports published between January 2011 and October 2021 and also consulted key informants for unpublished reports. We included studies that assessed salt intake from urinary sodium excretion, either spot urine or a 24 h urine sample, on a minimum of 100 samples in South Asian countries. We included 12 studies meeting the criteria after screening 2043 studies, out of which five followed nationally representative methods. This review revealed that salt intake in South Asian countries ranges from 6.7-13.3 g/day. The reported lowest level of salt intake was in Bangladesh and India, and the highest one was in Nepal. The estimated salt intake reported in the nationally representative studies were ranging from 8 g/day (in India) to 12.1 g/day (in Afghanistan). Salt consumption in men (8.9-12.5 g/day) was reported higher than in women (7.1-12.5 g/day). Despite the global target of population salt intake reduction, people in South Asian countries consume a much higher amount of salt than the WHO-recommended level.

Fluoride Exposure in Community Prevention Programmes for Oral Health Using Nail Clippings and Spot Urine Samples: A Systematic Review and Meta-Analysis.

Due to practical difficulties in quantifying fluoride exposure in populations, practical and accurate biomarkers can play a major role in the surveillance of fluoride. Among different fluoride biomarkers, spot urine and nail clippings have gained more attention due to their ease of acquisition. However, there is no robust consensus about the accuracy of these biomarkers for the estimation of fluoride exposure. This systematic review and meta-analysis aimed to synthesise evidence on the association between fluoride exposure and the fluoride concentration of spot urine and nail clippings. This review was conducted and reported using the PRISMA Statement. Nine databases (Medline, CINAHL, Web of Science, Scopus, ScienceDirect, Sage Journals Online, Campbell Collaboration, Cochrane Collaboration, and Embase); search engines (Google and Google Scholar); and grey literature were searched up to September 2022. All screening, data extraction, and quality assessments were conducted in duplicate. All experimental and observational research studies that reported the correlation between fluoride exposure and fluoride concentrations of spot urine and/or nail clippings were included. The Mixed-Methods Appraisal tool was used to assess the methodological quality of the included studies. A random effect meta-analysis was carried out to determine the relationship between fluoride exposure and fluoride concentration of biomarkers (i.e., spot urine and nail clippings). Forty-four studies met the inclusion criteria. A total of 694,578 participants were included in this review. Twenty-five studies were included in the meta-analysis. The primary meta-analysis showed a moderate correlation of 0.674 (95% confidence interval [CI]: 0.623-0.725, n = 25) between fluoride intake and fluoride concentration of spot urine and a strong correlation of 0.938 (95% CI: 0.520-1.355, n = 11) between fluoride intake and the fluoride concentration of nail clippings in all age groups. The findings of secondary meta-analyses showed a strong positive correlation between fluoride intake and fluoride/creatinine ratio of spot urine in children (0.929; 95% CI: 0.502-0.991; n = 2). In conclusion, spot urine and nail clippings have the potential to be employed as non-invasively obtained biomarkers in populations. However, due to the scarcity of high quality, relevant studies, more research is needed to establish the validity of these biomarkers.

Spot Urinary Creatinine Concentration in Patients with Chronic Heart Failure Identifies a Distinct Muscle-Wasting Phenotype with a Strikingly Different Risk of Mortality.

BACKGROUND: There is a raising awareness that heart failure (HF) is a highly heterogeneous, multiorgan syndrome with an increasing global prevalence and still poor prognosis. The comorbidities of HF are one of the key reasons for presence of various phenotypes with different clinical profile and outcome. Heterogeneity of skeletal muscles (SMs) quantity and function may have an impact on patient's phenotype. AIM: We intended to compare clinical characteristics of phenotypes defined by a combination of various SM mass taken as a fat-free compartment from DEXA scans and different levels of SUCR (Spot Urinary Creatinine). All-cause mortality with mortality predicted by MAGGIC in such phenotypes were compared. METHODS: In 720 HF patients with reduced ejection fraction (age: 52.3 ± 10 years, female: 14%, NYHA: 2.7 ± 0.7, LVEF: 24.3 ± 7.3%), admitted to the hospital for heart transplantation candidacy assessment, morning SUCR along with body composition scanning (DEXA) was performed. All study participants were dichotomized twice, first by low or normal appendicular muscle mass index (ASMI) and second by SUCR (Spot Urinary Creatinine) < and ≥of 1.34 g/L. Four study groups (phenotypes) were created as combinations of lower or higher SUCR and low or normal ASMI. RESULTS: Low ASMI was found in 242 (33.6%) patients, while the remaining 478 had normal muscle mass. In 446 patients (61.9%), SUCR was <1.34 g/L. During 3 years of follow-up, 223 (31.0%) patients died (all-cause). The phenotype of lower both ASMI and SUCR was associated with the highest mortality. The death rate in phenotype with both low ASMI and SUCR exceeded by 70% the risk estimated by MAGGIC. This difference was significant as judged by the 95% confidence interval for MAGGIC estimation. In Cox regression analysis adjusted for MAGGIC and parameters known to increase risk, the relative risk of patients with phenotype of low both ASMI and SUCR was elevated by 45-55% as compared to patients with all other phenotypes. The protective role of higher SUCR in patients with muscle wasting was, therefore, confirmed in Cox analysis. CONCLUSIONS: Measurement of SUCR in HF patients can identify clinical phenotypes with skeletal muscle wasting but strikingly different risk of death that is actually not captured by MAGGIC score. The higher level of SUCR was associated with similar risk independently of presence of muscle wasting. As the analysis of SUCR is cheap and easy to perform, it should be further tested as a potentially useful biomarker, which may precisely phenotype HF patients independently of their skeletal muscle status.

Accuracy of Spot Urine Albumin Creatinine Ratio With Respect to 24-Hour Urine Albumin for the Detection of Proteinuria in Antenatal Women With Preeclampsia: A Descriptive Study.

Background Among the hypertensive disorders of pregnancy, certain diseases like preeclampsia (PE) and eclampsia have the maximum impact on morbidity and mortality of the mother as well as the newborn. Proteinuria determination is used to assess renal damage in PE. There are several ways to evaluate proteinuria in pregnant women, but the gold standard remains the 24-hour urine albumin (24-h UA) excretion. Spot urine albumin creatinine ratio (UACR) can be used for rapid diagnosis of PE which is fast, reliable, and easy to use. Hence, our tertiary care center conducted the current study to assess the accuracy of spot UACR with 24-h UA for detecting proteinuria in antenatal women to diagnose PE and to evaluate the obstetric outcome in antenatal women with PE. Methodology A descriptive, cross-sectional study was conducted on 98 antenatal women diagnosed with PE. Urine albumin was done by dipstick method and the presence or absence of proteinuria was noted. Both, the 24-h urine sample and a random sample for spot UACR were sent for analysis. Results Spot UACR has more specificity than sensitivity along with a high negative predictive value for the detection of proteinuria. Additionally, significant proteinuria was associated with an increased rate of induced labor, a cesarean section in patients, lower mean gestational age at the time of delivery, lower birth weight, and increased rate of intrauterine fetal death. Conclusion The study concluded that spot UACR has more specificity than sensitivity along with a high negative predictive value for the detection of proteinuria and therefore, can be used for the diagnosis of proteinuria in women with PE. Hence, spot UACR is a reliable, faster, and more accurate method for the detection of proteinuria in PE and can be used for early diagnosis and timely management leading to a decrease in mortality and morbidity of the mother and the fetus.

Prognostic Value of Spot Urinary Creatinine Concentration and Its Relationship with Body Composition Parameters in HF Patients.

BACKGROUND: Low 24-h urinary excretion of creatinine in patients with heart failure (HF) is believed to reflect muscle wasting and is associated with a poor prognosis. Recently, spot urinary creatinine concentration (SUCR) has been suggested as a useful prognostic factor in selected HF cohorts. This more practical and cheaper approach has never been tested in an unselected HF population. Moreover, neither the relation between SUCR and body composition markers nor the association of SUCR with the markers of volume overload, which are known to worsen clinical outcome, has been studied so far. The aim of the study was to check the prognostic value of SUCR in HF patients after adjusting for body composition and indirect markers of volume overload. METHODS: In 911 HF patients, morning SUCR was determined and body composition scanning using dual X-ray absorptiometry (DEXA) was performed. Univariable and multivariable predictors of log SUCR were analyzed. All participants were divided into quartiles of SUCR. RESULTS: In univariable analysis, SUCR weakly correlated with fat-free mass (R = 0.09, p = 0.01). Stronger correlations were shown between SUCR and loop diuretic dose (R = 0.16, p < 0.0001), NTproBNP (R = -0.15, p < 0.0001) and serum sodium (R = 0.16, p < 0.0001). During 3 years of follow-up, 353 (38.7%) patients died. Patients with lower SUCR were more frequently female, and their functional status was worse. The lowest mortality was observed in the top quartile of SUCR. In the unadjusted Cox regression analysis, the relative risk of death in all three lower quartiles of SUCR was higher by roughly 80% compared to the top SUCR quartile. Apart from lower SUCR, the significant predictors of death were age and malnutrition but not body composition. After adjustment for loop diuretic dose and percent of recommended dose of mineralocorticoid receptor antagonists, the difference in mortality vanished completely. CONCLUSIONS: Lower SUCR levels in HF patients are associated with a worse outcome, but this effect is not correlated with fat-free mass. Fluid overload-driven effects may link lower SUCR with higher mortality in HF.

The associations of self-reported salt-intake and spot urine sodium with home blood pressure.

Purpose: A limited number of studies have suggested a nonlinear association between spot urine (SU) sodium concentration and office blood pressure (BP). We examined how SU sodium concentration and dietary salt obtained from a food frequency questionnaire are associated with more accurately measured home BP in a large, nationwide population sample.Materials and methods: We included 1398 participants in cross-sectional and 851 participants in 11-year longitudinal analyses. We investigated associations between baseline salt/sodium variables and (i) baseline and follow-up home BP; and (ii) prevalent and incident hypertension with linear and logistic regression models.Results: We observed positive associations (ß ± standard error) between salt/sodium variables and BP in unadjusted models. SU sodium concentration associated with baseline systolic (0.04 ± 0.01, p < 0.001) and diastolic (0.02 ± 0.01, p < 0.001) BP and follow-up systolic (0.03 ± 0.01, p = 0.003) and diastolic (0.02 ± 0.01, p < 0.001) BP. Dietary salt intake was associated with baseline (0.52 ± 0.19, p = 0.008) and follow-up (0.57 ± 0.20, p = 0.006) systolic BP. Compared to the lowest quintile of SU sodium concentration, the highest quintile had greater odds of prevalent hypertension (odds ratio [OR] 1.57, 95% confidence interval [CI] 1.12-2.19) and the second highest quintile with incident hypertension (OR 1.86, 95% CI 1.05-3.34). Unadjusted odds of incident hypertension were higher in the highest as compared to the lowest quintile of dietary salt intake (OR 1.83, 95% CI 1.01-3.35). After adjustments for sex, age, plasma creatinine concentration and alcohol intake, none of the aforementioned associations remained statistically significant. We found no evidence of a J-shaped association between the salt/sodium variables and BP or hypertension.Conclusion: SU sodium concentration and dietary salt intake are associated with home BP and hypertension only in some of the unadjusted models. Our results underscore that feasible estimation of sodium intake remains challenging in epidemiology.

What is known about the topicSome studies have suggested a non-linear association between spot urine sodium and blood pressure24-hour urinary sodium sampling is the gold standard method for assessing sodium intakeWhat this study addsMultiple fractional polynomials did not reveal evidence of a J-shaped association between spot urine sodium or dietary salt intake (measured by a questionnaire) and home blood pressurePrecise and yet feasible estimation of sodium intake remains challenging in epidemiology.

Urinary Sucrose and Fructose From Spot Urine May Be Used as a Predictive Biomarker of Total Sugar Intake-Findings From a Controlled Feeding Study.

BACKGROUND: Recently, we confirmed 24-h urinary sucrose plus fructose (24 uSF) as a predictive biomarker of total sugar intake. However, the collection of 24-h urine samples has limited feasibility in population studies. OBJECTIVE: We investigated the utility of the urinary sucrose plus fructose (uSF) biomarker measured in spot urine as a measure of 24 uSF biomarker and total sugar intake. METHODS: Hundred participants, 18-70 y of age, from the Phoenix Metropolitan Area completed a 15-d feeding study. For 2 of the 8 collected 24-h urine samples, each spot urine sample was collected in a separate container. We considered 4 timed voids of the day [morning (AM) void: first void 08:30-12:30; afternoon (PM) void: first void 12:31-17:30; evening (EVE) void: first void 17:31-12:00; and next-day (ND) void: first void 04:00-12:00]. We investigated the performance of uSF from 1 void, and uSF combined from 2 and 3 voids as a measure of 24 uSF and sugar intake. RESULTS: The biomarker averaged from PM/EVE void strongly correlated with 24 uSF (partial r = 0.75). The 24 uSF predicted from the PM/EVE combination was significantly associated with observed sugar intake and was selected for building the calibrated biomarker equation (marginal R2 = 0.36). Spot urine-based calibrated biomarker, ie, biomarker-estimated sugar intake was moderately correlated with the 15-d mean-observed sugar intake (r = 0.50). CONCLUSIONS: uSF measured from a PM and EVE void may be used to generate biomarker-based sugar intake estimate when collecting 24-h urine samples is not feasible, pending external validation.