Estimation of sodium consumption by novel formulas derived from random spot and 12-hour urine collection

The gold standard for estimating sodium intake is 24h urine sodium excretion. Several equations have been used to estimate 24h urine sodium excretion, however, a validated formula for calculating 24h urine sodium excretion from 12h urine collection has not yet been established. This study aims to develop novel equations for estimating 24h urine sodium excretion from 12h and random spot urine collection and also to validate existing spot urine equations in the Thai population. A cross-sectional survey was carried out among 209 adult hospital personnel. Participants were asked to perform a 12h daytime, 12h nighttime, and a random spot urine collection over a period of 24 hours. The mean 24h urine sodium excretion was 4,055±1,712 mg/day. Estimated urine sodium excretion from 3 different equations using random spot urine collection showed moderate correlation and agreement with actual 24h urine sodium excretion (r = 0.54, P<0.001, ICC = 0.53 for Kawasaki; r = 0.57, P<0.001, ICC = 0.44 for Tanaka; r = 0.60, P<0.001, ICC = 0.45 for INTERSALT). Novel equations for predicting 24h urine sodium excretion were then developed using variables derived from 12h daytime urine collection, 12h nighttime urine collection, random spot urine collection, 12h daytime with random spot urine collection, and 12h nighttime with random spot urine collection which showed strong correlation and agreement with actual measured values (r = 0.88, P<0.001, ICC = 0.87; r = 0.83, P<0.001, ICC = 0.81; r = 0.67, P<0.001, ICC = 0.62; r = 0.90, P<0.001, ICC = 0.90; and r = 0.83, p<0.001, ICC = 0.82 respectively). Bland-Altman plots indicated good agreement between predicted values and actual 24h urine sodium excretion using the new equations. Newly derived equations from 12h daytime and 12h nighttime urine collection with or without casual spot urine collection were able to accurately predict 24h urine sodium excretion.

Association of age and dietary sodium intake in patients with heart failure: testing mediating effects of preference for salt and enjoyment of sodium-restricted diet

Funding Acknowledgements Type of funding sources: Other. Main funding source(s): National Institutes of Health (NIH) Background The poor taste foods in a low sodium diet and patients’ preferences for salty foods are known barriers to sodium restricted diet (SRD) adherence. Older adults may experience less enjoyment of SRD due to decreased sense of taste. However, little is known about how age is associated with sodium intake, preference for salt, and enjoyment of SRD in patients with heart failure (HF). Purpose The purpose of this study was to examine effect of age on dietary sodium intake through their preference for salt and enjoyment of SRD in patients with HF. Methods In this cross-sectional study, we used baseline data from participants in a randomized controlled trial of a SRD intervention for patients with HF and their caregivers. Patients were asked to collect 24-hour urine to measure dietary sodium intake. Preference for salty food and enjoyment of SRD were assessed using a question on an 11-point numeric scale (range 0 to 10). Parallel mediation analyses were conducted using the PROCESS macro program in SPSS with 5,000 bootstrap samples. Results A total of 136 patients with HF (64% male, mean age = 60.3 ± 14.4, range 27 to 90, 80.1% white) had a mean 24-hr urine sodium of 4320mg (SD = 2053, range: 1553 mg – 11495 mg) with most (71%) having a 24-hr urine sodium &gt; 3000mg. The mean preference for salty food was 5.3 (SD = 2.8) on a scale from 0 to 10 with 10 indicating greater preference and enjoyment of SRD was 4.4 (SD = 2.5) on the same scale. Age was significantly associated with sodium intake in that older patients were more likely to eat less sodium (effect= -40.3236, 95% CI= [-63.7151, -16.9321]). The indirect effects of age on sodium intake through preference of salty food (effect= .7033, 95% CI = [-2.3361, 4.5357]) and enjoyment of SRD (effect = -.0271, 95% CI = [ -3.2736, 2.2213]) were not significant, indicating that these factors did not mediate the relationship between age and dietary sodium consumption. When we controlled gender, education, and ethnicity, age was also associated with sodium intake, but the two indirect effects were not significant. Conclusion Although most patients consumed foods high in sodium, older patients were more likely to consume foods lower in salt. However, contrary to what we expected, preference for salty foods and enjoyment of SRD did not play mediator roles in the association of age with salt consumption. The findings suggest that older adults may need different types of intervention to promote adherence than younger patients. Further research is needed to explore other factors related to SRD (e.g., efficacy of SRD or perceived control of diet behaviors) that affect sodium intake in patients with HF.

Diagnostic usefulness of the spot urine sodium/potassium ratio in cirrhotic patients with ascites

Background and aims The low-salt diet is considered important for control of ascites in cirrhotic patients. To validate whether the spot urine sodium (Na)/potassium (K) ratio could replace 24-h urine Na (uNa) excretion in assessing low-salt diet compliance. Methods We prospectively studied 175 patients. 24-h urine collection and spot urine collection were performed. Subsequently, 24-h uNa, urine creatinine (uCr), and spot urine Na and K were assessed. A complete urine collection was confirmed based on 24-h uCr excretion levels of 15mg/kg/day for men and 10mg/kg/day for women. The area under the receiver operating characteristic (AUROC) curve analysis was performed to evaluate the feasibility of spot urine Na/K ratio in predicting 24-h uNa greater than 78mmol/day. Results Out of 175 patients, 24-h urine samples were completely collected in 57 patients only. Moreover, urine samples were not completely collected in 118 patients because their 24-h uCr excretion level was less than the established criteria. In complete urine collection group, AUROC curve for spot urine Na/K ratio in predicting 24-h uNa greater than 78mmol/day was 0.874±0.051 (P<0.001). In the incomplete urine collection group, the AUROC was 0.832±0.039 (P<0.001). In complete urine collection group, the classical cutoff value greater than 1.0 of spot urine Na/K ratio showed 90.9% sensitivity and 56.0% specificity. Conclusions The spot urine Na/K ratio reflects 24-h uNa, but the AUROC value obtained in this study is lower than that of a previous study. Considered the large number of patients with incomplete urine collection, validating 24-h complete urine collection criteria is necessary.

Abstract P093: Sex-stratified Associations Of Urine Electrolytes With 10th & 90th Percentiles Of Systolic Blood Pressure Distribution

Introduction: Electrolytes intake influence systolic blood pressure (SBP). Studies often explore the association of urine electrolytes with the conditional mean difference of SBP, but limited data exist on the sex-specific associations of urine electrolytes’ excretion with low and high end SBP distribution. We examined the sex-stratified association of urine electrolytes with the 10th and 90th percentiles of SBP. Methods: We pooled 9,804 person-visits (n =1467 participants) data of 24-hour urine electrolytes and SBP from three cohorts in coastal Bangladesh. We created sex-stratified restricted cubic spline (RCS) plots from quantile regression for illustrating the associations of urine sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) excretion with the 10th and 90th percentile of SBP distribution, adjusted for age, body mass index, physical activity, smoking, alcohol consumption, sleep hours, religion, household wealth, cohort ID, and seasonality. Four knots at the 5th, 35th, 65th, and 95th percentiles of each electrolyte distribution were used to create RCS plots. Results: We found linear positive associations for urine Na with 10th and 90th percentiles of SBP for males, but such association for the 10th percentile of SBP for females was less steep. Negative associations were found between urine K and SBP for males for the 90th percentile of SBP; no such association was found for the 10th percentile of SBP. Linear negative associations were found between urine Mg and SBP for males for both the 10th and 90th percentile of SBP distributions, but not for females. There was no association of urine Ca and SBP for both sexes for the 10th percentile of SBP, but negative associations existed for the 90th percentile of SBP for males. Conclusion: Sex-specific associations of urine electrolytes and SBP varied for the low and high end of SBP distribution. Males with higher SBP could benefit from high urine K, Ca, and Mg, representing high intakes of these minerals. However, such benefits may not be present for females.

Estimating 24 Hour Sodium Urine from Spot Urine: A Correlation Model Among Aged 25-64 in Indonesia

INTRODUCTION: Excess salt intake is known to raise blood pressure and turn increase the risk of cardiovascular disease. Data and information on sodium consumption in Indonesia based is limited, while examination method using 24-hour urine examination is a complex method to apply in population based survey. Objective: to estimate value of spot urinary excretion against 24-hour urine values ​​and correction factors. METHOD: Validation was carried out through 24-hour urine and spot urine examination, in 423 individual aged 25-65 years in t Kebun Kelapa Village, Bogor City, Indonesia in 2017. Urine sodium examination method was carried out by laboratory examination inductively coupled plasma optical emission spectrometry (ICP-OES). Accuracy and precision are valued by paired test correlations and mean differences. The coefficient of determination (R Square) of is calculated for sodium intake estimation and correction factors. RESULTS: The morning value of sodium spot urine has better precision and a stronger correlation with the 24-hour sodium urine than the afternoon spot urine. The difference in average morning sodium urine with 24-hour urine sodium according to age and sex was not significantly different (t test 0.30 and p = 0.77), had a positive and moderate correlation (paired r = 0.50 and p = 0.00). The average difference between the estimated evening urine sodium spot was different (t test = 7.32 and p = 0.00), and the correlation was very weak (r = 0.25; p = 0.00). CONCLUSION: The urine content / sodium spot level was accurate to estimate urine sodium value / content 24 hours.

Roles of sodium-glucose cotransporter 2 of mesangial cells in diabetic kidney disease

We have been studying the presence of sodium-glucose cotransporter 2 (SGLT2) in mesangial cells and pericytes since 1992. Recent large placebo-controlled studies of SGLT2 inhibitors in patients with type 2 diabetes mellitus have reported desirable effects of the inhibitors on the diabetic kidney and the diabetic heart. Most studies have indicated that these effects of SGLT2 inhibitors could be mediated by the tubuloglomerular feedback (TGF) system. However, a recent study about urine sodium excretion in the presence of an SGLT2 inhibitor did not show any increases in urine sodium excretion. A very small dose of an SGLT2 inhibitor did not inhibit SGLT2 at the S1 segment of proximal tubules. Moreover, SGLT2 inhibition protects against progression in chronic kidney disease with and without type 2 diabetes. In these circumstances, the TGF hypothesis involves several theoretical concerns that must be clarified. The presence of SGLT2 in mesangial cells seems to be very important for diabetic nephropathy. We now propose a novel mechanism by which the desirable effects of SGLT2 inhibitors on diabetic nephropathy are derived from the direct effect on SGLT2 expressed in mesangial cells.

Development and double cross-validation of new spot urine sodium equation to predict 24-h urine sodium in the Malaysian population

Background Monitoring sodium intake through 24-h urine collection sample is recommended, but the implementation of this method can be difficult. The objective of this study was to develop and validate an equation using spot urine concentration to predict 24-h sodium excretion in the Malaysian population. Methods This was a Malaysian Community Salt Study (MyCoSS) sub-study, which was conducted from October 2017 to March 2018. Out of 798 participants in the MyCoSS study who completed 24-h urine collection, 768 of them have collected one-time spot urine the following morning. They were randomly assigned into two groups to form separate spot urine equations. The final spot urine equation was derived from the entire data set after confirming the stability of the equation by double cross-validation in both study groups. Newly derived spot urine equation was developed using the coefficients from the multiple linear regression test. A Bland-Altman plot was used to measure the mean bias and limits of agreement between estimated and measured 24-h urine sodium. The estimation of sodium intake using the new equation was compared with other established equations, namely Tanaka and INTERSALT. Results The new equation showed the least mean bias between measured and predicted sodium, − 0.35 (− 72.26, 71.56) mg/day compared to Tanaka, 629.83 (532.19, 727.47) mg/day and INTERSALT, and 360.82 (284.34, 437.29) mg/day. Predicted sodium measured from the new equation showed greater correlation with measured sodium (r = 0.50) compared to Tanaka (r =0.24) and INTERSALT (r = 0.44), P < 0.05. Conclusion Our newly developed equation from spot urine can predict least mean bias of sodium intake among the Malaysian population when 24-h urine sodium collection is not feasible.

Challenges of Managing and Diagnosing Reset Osmostat vs SIADH in a Patient With Personal and Family History of Chronic Hyponatremia

Background: Distinguishing between a reset osmostat and SIADH in a hyponatremic patient can prove to be challenging in certain circumstances. Reset osmostat is an uncommon and under recognized cause of hyponatremia. Thus, it is important to recognize it as it does not require any treatment. Clinical Case: A 48 year old male with history of chronic hyponatremia of unknown cause, fatty liver, hypertension, was in the hospital post operatively after resection of a meningioma along dura. Endocrine was consulted for management of his chronic hyponatremia. Had chronic hyponatremia for over 20 years and was always asymptomatic. Normally drank 6-7 L of water at home, mostly at night. Also found to have a spinal compression fracture of unknown cause. Both his father and brother had chronic hyponatremia of unknown cause as well, suggesting possible familial component. His baseline sodium levels were 129-133 mmol/L. In the hospital, serum sodium levels decreased to the 120s. TSH was 0.307mcunit/mL (0.27-4.2). Was also placed on 1.5 L fluid restriction. Urine osmolality was 900 mOsm/kg (500-800) with sodium of 123 mmol/L (136-145), consistent with SIADH. A rare inherited disorder, nephrogenic SIADH (NSIADH), was considered. However, it has an X-linked inheritance pattern. Fluid restriction was removed, then did fluid load with 2L of water and obtained urine sodium, serum sodium, urine osmolality, serum osmolality, Copeptin (pro-AVP) before fluid load and 1 hour after fluid load. Serum sodium level went from 127mmol/L before to 125 mmol/L after. Urine osmolality improved from 984 mOsm/kg prior to 575 mOsm/kg after. Urine sodium went from 183 mmol/L prior to 91 mmol/L after. Serum osmolality went from 278 mOsm/kg (270-310) to 268 mOsm/kg after. His co-peptin pro-AVP levels were 16.4 pmol/L (ref. &lt;13.1). They are found to be low in NSIADH. It was decided that his chronic hyponatremia was likely due to reset osmostat. After discharge and follow up, his serum sodium was rechecked and was 128 mmol/L. It would have been challenging, but useful, to try a vaptan for diagnostic purposes and possibly to increase serum sodium. However, there are complications from overcorrection. Since patient had long standing asymptomatic chronic hyponatremia with family history, it was decided not to pursue aggressive measures just to “normalize” serum sodium. Otherwise, it would have been an example of treating the numbers and not the patient. Conclusions: Case demonstrates the importance of keeping the patient, their symptoms, and clinical picture in mind, and to not just follow numbers, as difficult as it may be, especially when managing conditions in which diagnosis may be uncertain or unclear. Sometimes no intervention is needed at all, however tempting it may be to do one, it is important to keep the former option in mind. An asymptomatic patient with longstanding chronic hyponatremia due to reset osmostat is an example of that.

A Case of Inappropriate Antidiuretic Hormone Secretion Syndrome Associated With COVID-19 Pneumonia Treated With Boluses of Hypertonic Saline for Reversal of Symptomatic Hyponatremia

Hyponatremia is the most common electrolyte disorder, which can occur in outpatients and hospitalized patients, so both first-contact doctors and specialists must keep up-to-date on the prevention, recognition, diagnosis and management of this complication. A 68-year-old male patient presents to Dos de Mayo National Hospital Emergency Department. He was diagnosed as COVID-19 pneumonia and hospitalized for management of acute respiratory failure. The patient had neurological impairment associated with poor oral tolerance. Initial laboratory examinations were C-reactive protein in 363.5 mg/L, serum sodium of 128.42 mmol/L and urine sodium was 83 meq/L. Osmolality in plasma was 266.15 mOsm/Kg and urine osmolality was 420 mOsm/Kg. Thyroid function tests as well as cortisol levels were in normal range. Our patient was diagnosed as SIAD by hyponatremia, osmolality in plasma &lt;275 mOsm / kg, urine osmolality &gt; 100 mOsm / kg, urine sodium &gt; 40 mEq / l, euvolemic state and exclusion of cortisol and thyroid hormone deficiency. Treatment of hyponatremia was initiated and rapidly elevate plasma sodium by 4 meq/l in the first 6 hours. There was clinical improvement. Blood sodium levels ranged from 115 to 135 mmol/L with bolus therapy of hypertonic solutions in 72 hours. Intravenous boluses of hypertonic saline should be administered to rapidly elevate plasma sodium by 4 to 6 mEq/L in the first 6 hours. The data shows that fluid bolus therapy is more effective in acutely elevating plasma sodium than traditional low-dose hypertonic saline infusion that may lead to avoidable deaths according to recent guidelines. In this case a strategy based with bolus therapy for reversal of hyponatremia was used effectively. A number of cases of COVID-19 pneumonia are associated with SIAD. The presence of SIAD could be a clue to diagnosing COVID-19. SIAD is a major complication of COVID-19 and could be the first and only manifestation. In cases of SIAD without a clear etiology we should suspect COVID-19 in a patient with respiratory distress in the current pandemic. Syndrome of inappropiate antidiuresis (SIAD) should be assessed in every patient with COVID-19 as their treatment and early identification decreases mortality. The association between COVID-19 pneumonia and SIAD should be further identified, requiring doctors to be aware of this condition. Additional studies are required to determine the incidence and pathogenesis of SIAD in patients with COVID-19.