Clinical relevance of proteinuria selectivity index and fractional excretion of sodium in patients with nephrotic syndrome.

Proteinuria selectivity index (PSI) is a potential tool for histological classification and prediction of treatment response in nephrotic syndrome, but evidence is insufficient. Clinical relevance of fractional excretion of sodium (FENa) in nephrotic syndrome remains largely unexplored. This multicenter retrospective study included patients with nephrotic syndrome who underwent kidney biopsy between January 2012 and June 2022. Optimal cutoffs for predicting complete remission based on PSI and FENa were determined using receiver operating characteristic curves. Patients were divided into two groups using these cutoffs and followed until complete remission. Of the 611 patients included, 177 had minimal change disease (MCD), 52 had focal segmental glomerulosclerosis (FSGS), and 149 had membranous nephropathy (MN). Median (interquartile range) PSI were 0.14 (0.09-0.19) for MCD, 0.33 (0.23-0.40) for FSGS, and 0.20 (0.14-0.30) for MN. FENa were 0.24 (0.09-0.68), 1.03 (0.50-2.14), and 0.78 (0.41-1.28). Patients with low PSI and FENa had a higher incidence of complete remission. Cox regression analyses demonstrated that both parameters were associated with achieving complete remission (HR 2.73 [95% CI 1.97-3.81] and HR 1.93 [95% CI 1.46-2.55], respectively). PSI and FENa may be useful for histological classification and predicting remission in nephrotic syndrome.

Association of Urinary Sodium, Potassium, and the Sodium-to-Potassium Ratio with Impaired Kidney Function Assessed with 24-H Urine Analysis.

Background: Albuminuria and albumin excretion rate (AER) are important risk factors for chronic kidney disease (CKD) development. Despite the extensive evidence of the influence of sodium and potassium on cardiovascular health, the existing evidence regarding their impact on albuminuria and kidney disease is limited and inconsistent. Our study aimed to assess the correlation between urinary sodium and potassium excretion, and the sodium-to-potassium ratio (Na/K ratio) with impaired kidney function, particularly the AER and albuminuria. Materials and Methods: Data were collected from the Lithuanian NATRIJOD study. A total of 826 single 24-h urine samples from individuals aged 18 to 69 were collected and analyzed for their sodium and potassium levels, Na/K ratio, and AER. Albuminuria was defined as an AER exceeding 30 mg/24 h. Results: The participant mean age was 47.2 ± 12.1 years; 48.5% of the participants were male. The prevalence of albuminuria was 3%. Correlation analysis revealed a positive correlation between AER and urinary sodium excretion (rs = 0.21; p < 0.001) and urinary potassium excretion (rs = 0.28; p < 0.001). In univariate linear regression analysis, sodium and potassium excretion and the Na/K ratio were significant AER predictors with ß coefficients of 0.028 (95% CI: 0.015; 0.041; p < 0.001), 0.040 (95% CI: 0.003; 0.077; p = 0.035), and 1.234 (95% CI: 0.210; 2.259; p = 0.018), respectively. In the multivariable model, only urinary sodium excretion remained significant, with a ß coefficient of 0.028 (95% CI: 0.016; 0.041). Potential albuminuria predictive factors identified via univariate logistic regression included urinary sodium excretion (OR 1.00; 95% CI: 1:00; 1.01) and the Na/K ratio (OR 1.53; 95% CI: 1.11; 2.05). However, these factors became statistically insignificant in the multivariate model. Conclusions: Urinary sodium and potassium excretion and the Na/K ratio are significantly associated with kidney damage, considering the assessed 24-h albumin excretion rate and presence of albuminuria content.

SETD2 regulates SLC family transporter-mediated sodium and glucose reabsorptions in renal tubule.

A regulatory mechanism for SLC family transporters, critical transporters for sodium and glucose reabsorptions in renal tubule, is incompletely understood. Here, we report an important regulation of SLC family transporter by SETD2, a chromatin remodeling gene whose alterations have been found in a subset of kidney cancers. Kidney-specific inactivation of Setd2 resulted in hypovolemia with excessive urine excretion in mouse and interestingly, RNA-sequencing analysis of Setd2-deficient murine kidney exhibited decreased expressions of SLC family transporters, critical transporters for sodium and glucose reabsorptions in renal tubule. Importantly, inactivation of Setd2 in murine kidney displayed attenuated dapagliflozin-induced diuresis and glucose excretion, further supporting that SETD2 might regulate SLCfamily transporter-mediated sodium and glucose reabsorptions in renal tubule. These data uncover an important regulation of SLC family transporter by SETD2, which may illuminate a crosstalk between metabolism and epigenome in renal tubule.

Study of Urinary Electrolytes and Fractional Excretion of Uric Acid in Evaluating Hyponatremia.

INTRODUCTION: Serum sodium levels <135 mmol/L are known as hyponatremia. The syndrome of inappropriate antidiuresis (SIAD), which is described by a drop in the effective arterial blood volume (EABV), is the most common cause of hyponatremia. This study was carried out to categorize hyponatremia based on volume status and on parameters like fractional excretion of uric acid (FE-UA), fractional excretion of sodium (FE-Na), urine uric acid (U-UA), and serum uric acid (SR-UA) values. MATERIALS AND METHODS: Sixty-one patients admitted to the Department of Medicine at Rajendra Institute of Medical Sciences (RIMS), Ranchi, with hyponatremia were included in the study by applying random sampling. Routine urine and blood samples were collected for biochemical tests. Institutional ethical clearance was obtained for this study. Data were analyzed using Statistical Package for the Social Sciences (SPSS) (version 21). Frequency, central tendency, receiver operating characteristic (ROC), and nonparametric Mann-Whitney U test analysis tools were utilized for analysis. RESULTS: Syndrome of inappropriate antidiuretic hormone secretion (SIADH) was found in nearly 50.82% of hyponatremic patients. Approximately, 70% of non-SIADH patients were hypovolemic. When compared to the non-SIADH group, patients in the SIADH group had significantly higher systolic blood pressure (SBP) and diastolic blood pressure (DBP), lower pulse rates, and lower urine creatinine levels and urine creatinine to serum creatinine ratio. The non-SIADH group had significantly higher SR-UA levels (p < 0.0001), but the SIADH group had significantly higher U-UA levels and significantly lower SR-UA levels. Among the studied parameters, FE-UA was the most accurate in diagnosing SIADH. FE-UA (>12%) is a better diagnostic marker for distinguishing SIADH patients from non-SIADH patients. CONCLUSION: FE-uric acid was found to be the most superior in diagnosing SIADH, followed by FE-Na.

[Sodium depletion assessed by the urinary sodium/creatinine ratio in monitoring cystic fibrosis patients]. / Déplétion sodée évaluée par le ratio sodium/créatinine urinaire dans le suivi des patients atteints de mucoviscidose.

As a result of excessive salt loss, cystic fibrosis patients are at risk of dehydration, especially in hot weather. The urinary sodium/creatinine ratio is an easy and noninvasive tool for assessing whether dietary salt intake is adequate, whatever the patient's age. Recently, new reference values have been established, adapted to the patient's age. The objectives of this study are to investigate the impact of these new standards on the diagnosis of inadequate sodium intake and the variation in this ratio as a function of body mass index (BMI), outdoor temperature and the use of modulator therapy of CFTR protein. The present study included 40 patients and 335 urine samples. Adapting the urinary sodium/creatinine ratio with the new reference values reduced the number of patients with sodium deficiency by 11.8%. However, there were no significant differences in BMI, lung function or outdoor temperature between the sodium deficient and non-deficient groups. The CFTR modulator-treated group had a better mean urinary sodium/creatinine ratio compared with the group without modulators (p = 0.01), However, larger-scale studies are needed to provide a definitive answer to this question.

Suite à des pertes excessives en sel, les patients atteints de mucoviscidose sont à risque de déshydratation, surtout lors de fortes chaleurs. Le ratio sodium/créatinine urinaire est un outil simple et non invasif permettant d'évaluer l'adéquation des apports en sel dans l'alimentation du patient quel que soit son âge. Récemment, de nouvelles valeurs de référence ont été établies en fonction de l'âge. Les objectifs de cette étude sont d'étudier la répercussion de ces nouvelles normes sur le constat d'un apport sodé insuffisant pour le patient ainsi que la variation de ce ratio en fonction de l'indice de masse corporelle (IMC), de la température extérieure et de la prise d'un modulateur de la protéine CFTR. Cette étude comporte 40 patients et un total de 335 prélèvements urinaires. L'adaptation du ratio sodium/créatinine urinaire permet de réduire de 11,8 % le nombre de patients en déficit sodé. Il n'y a, par contre, pas de différences significatives concernant l'IMC, la fonction respiratoire et les températures extérieures, entre les groupes avec ou sans déficit sodé. Le groupe traité par un modulateur de la protéine CFTR a un meilleur ratio sodium/créatinine urinaire moyen en comparaison au groupe sans ce traitement (p = 0,01). Cependant, des études à plus large échelle sont nécessaires pour répondre de façon formelle à la question.

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

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

The utility of urine sodium-guided diuresis during acute decompensated heart failure.

Diuresis to achieve decongestion is a central aim of therapy in patients hospitalized for acute decompensated heart failure (ADHF). While multiple approaches have been tried to achieve adequate decongestion rapidly while minimizing adverse effects, no single diuretic strategy has shown superiority, and there is a paucity of data and guidelines to utilize in making these decisions. Observational cohort studies have shown associations between urine sodium excretion and outcomes after hospitalization for ADHF. Urine chemistries (urine sodium ± urine creatinine) may guide diuretic titration during ADHF, and multiple randomized clinical trials have been designed to compare a strategy of urine chemistry-guided diuresis to usual care. This review will summarize current literature for diuretic monitoring and titration strategies, outline evidence gaps, and describe the recently completed and ongoing clinical trials to address these gaps in patients with ADHF with a particular focus on the utility of urine sodium-guided strategies.

Calibration of 24-h urinary sodium excretion estimates from fasting morning urine in Chinese populations: a comparative analysis of 2 calibration models and a locally developed model.

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.

Mendelian randomization study of sodium-glucose cotransporter 2 inhibitors in cardiac and renal diseases.

OBJECTIVE: Sodium-glucose cotransporter 2 inhibitors (SGLT2i) target the reabsorption of sodium and glucose in the kidney proximal tubules to reduce blood sugar levels. However, clinical randomized controlled trials on SGLT2i have yielded inconsistent results, necessitating further research into their efficacy and safety for specific cardiac and renal diseases. METHODS: "Sodium in urine" was selected as a downstream biomarker of SGLT2i. Single nucleotide polymorphisms were extracted from genome-wide association study data as instrumental variables. Mendelian randomization analysis was then conducted for cardiac and renal diseases and potential adverse events. The causal effects of SGLT2i on these diseases were determined based on inverse variance weighted results, followed by sensitivity and pleiotropy tests. RESULTS: SGLT2i had a significant protective effect against nephrotic syndrome (odds ratio [OR] 0.0011, 95% confidence interval [CI] 0.000-0.237), chronic glomerulonephritis (OR 0.0002, 95% CI 0.000-0.21), and hypertensive nephropathy (OR 0.0003, 95% CI 0.000-0.785). No causal effects were observed between SGLT2i and cardiac diseases or potential adverse events. CONCLUSIONS: SGLT2i can act as protective factors against nephrotic syndrome, chronic glomerulonephritis, and hypertensive nephropathy.

Glucocorticoid-induced acute diuresis in rats in relation to the reduced renal expression of sodium-dependent cotransporter genes.

Although several studies have shown that glucocorticoids exert diuretic effects in animals and humans, the underlying mechanism responsible for the acute diuretic effect remains obscure. Here we examined the mechanism in terms of gene-expression. We observed that glucocorticoids, including dexamethasone (Dex) and prednisolone (PSL), acutely induced diuresis in rats in a dose-dependent manner. Free water clearance values were negative after Dex or PSL treatment, similar to those observed after treatment with osmotic diuretics (furosemide and acetazolamide). Dex significantly increased the urinary excretion of sodium, potassium, chloride, glucose, and inorganic phosphorus. Renal microarray analysis revealed that Dex significantly altered the renal expression of genes related to transmembrane transport activity. The mRNA levels of sodium/phosphate (NaPi-2a/Slc34a1, NaPi-2b/Slc34a2, and NaPi-2c/Slc34a3) and sodium/glucose cotransporters (Sglt2/Slc5a2) were significantly reduced in the Dex-treated kidney, being negatively correlated with the urinary excretion of their corresponding solutes. Dex did not affect renal expression of the natriuretic peptide receptor 1 (Npr1) gene, or the expression, localization, and phosphorylation of aquaporin-2 (AQP2), a water channel protein. These findings suggest that the acute diuretic effects of glucocorticoids might be mediated by reduced expression of sodium-dependent cotransporter genes.

Potassium and ammonium recovery in treated urine by zeolite based mixed matrix membranes.

Nitrogen, phosphorus and potassium are essential for crop growth, which are abundant in urine. Although numerous studies have developed techniques to recover ammonium and phosphorus from urine, limited research made efforts on the recovery of potassium, which is a non-renewable resource with uneven global distribution. In this study, we explored the possibility of zeolite based mixed matrix membranes (MMMs) to selectively recover ammonium and potassium from urine, with minimal detention of sodium. The findings demonstrated that upon the pre-treatment of zeolites with sodium chloride solution, a 70 wt% zeolite loaded MMM could achieve 69.3 % recovery of potassium and almost full recovery of ammonium. By varying the desorption temperatures and MMMs production process, it was discovered that stepwise backwash at low temperature (276 K) greatly lowered sodium recovery whilst simultaneously enhancing the recovery of potassium and ammonium. This study demonstrates the potential of recovering potassium and ammonium from urine using zeolite-loaded MMMs, coupled with achieving low-sodium recovery.

Assessment of exercise-induced dehydration in underhydrated athletes: Which method shows the most promise?

BACKGROUND & AIMS: Athletes are commonly exposed to exercise-induced dehydration. However, the best method to detect dehydration under this circumstance is not clear. This study aimed to analyze pre- and post-dehydration measurements of biomarkers, including saliva osmolality (SOsm), urine osmolality (UOsm), urine-specific gravity (USG), urine color (Ucolor), serum osmolality (SeOsm), serum arginine vasopressin (AVP), serum sodium (Na+), and thirst sensation in underhydrated athletes, using the body mass loss (BML) as the reference method. METHODS: In this clinical trial (NCT05380089), a total of 38 athletes (17 females) with a regular low water intake (<35 mL/kg/day) were submitted to exercise-induced dehydration with a heat index of 29.8 ± 3.1 °C and an individualized running intensity (80-90% of first ventilatory threshold). RESULTS: ROC curve analysis revealed significant discriminative abilities of SOsm, with AUC values of 0.76 at 1.5% BML, 0.75 at 1.75% BML, and 0.87 at 2% BML, while Na+ and SeOsm showed the highest AUC of 0.87 and 0.91 at 2% BML, respectively. SOsm showed high sensitivity at 1.5% of BML, while SeOsm and Na+ demonstrated high sensitivity at 2% of BML. CONCLUSION: This study highlights SOsm as a potential indicator of hydration status across different levels of BML. Additionally, Na+ and SeOsm emerged as accurate dehydration predictors at 1.75% and 2% of BML. Notably, the accuracy of urinary indices and thirst sensation for detecting hydration may be limited.

Dark tea consumption is associated with a reduced risk of dysglycaemia and increased urinary glucose and sodium excretion in Chinese adults.

AIM: To examine the associations of tea consumption (both frequency and type) with (1) prediabetes and diabetes and (2) urinary glucose and sodium excretion in Chinese community-dwelling adults. MATERIALS AND METHODS: In 1923 participants (457 with diabetes, 720 with prediabetes, and 746 with normoglycaemia), the frequency (occasional, frequent, daily, or nil) and type (green, black, dark, or other) of tea consumption were assessed using a standardized questionnaire. Morning spot urinary glucose and urine glucose-to-creatinine ratios (UGCRs) were assessed as markers of urinary glucose excretion. Tanaka's equation was used to estimate 24-h urinary sodium excretion. Logistic and multivariate linear regression analyses were performed. RESULTS: Compared with non-tea drinkers, the corresponding multivariable-adjusted odds ratios (ORs) for prediabetes and diabetes were 0.63 (95% confidence interval [CI] 0.48, 0.83) and 0.58 (95% CI 0.41, 0.82) in participants drinking tea daily. However, only drinking dark tea was associated with reduced ORs for prediabetes (0.49, 95% CI 0.36, 0.66) and diabetes (0.41, 95% CI 0.28, 0.62). Dark tea consumption was associated with increased morning spot urinary glucose (0.22 mmol/L, 95% CI 0.11, 0.34 mmol/L), UGCR (0.15 mmol/mmol, 95% CI 0.05, 0.25 mmol/L) and estimated 24-h urinary sodium (7.78 mEq/day, 95% CI 2.27, 13.28 mEq/day). CONCLUSIONS: Regular tea consumption, especially dark tea, is associated with a reduced risk of dysglycaemia and increased urinary glucose and sodium excretion in Chinese community-dwelling adults.

Diuretic resistance in acute heart failure: proposal for a new urinary sodium-based definition.

BACKGROUND: Diuretic resistance is a relevant clinical issue in acute heart failure (AHF), but a standardized, quantitative definition is still missing. The aim of this analysis was to highlight discrepancies between previously proposed definitions of diuretic response and to propose a new urinary sodium (NaU)-based definition of diuretic efficiency (DE) to identify diuretic resistant (DR) patients. METHODS: Three historical definitions of diuretic response and a new NaU-based DE definition, evaluating total NaU after the first diuretic bolus per 40 mg furosemide administered, were applied in a retrospective analysis to an AHF population treated with intravenous (i.v.) loop diuretics. Baseline characteristics, in-hospital clinical data and outcomes at discharge and mid-term follow-up were collected and compared among DR and non-DR patients for each definition. RESULTS: Among 53 patients, 39 (73.6%), 51 (96.2%) and 3 (5.7%) were DR according to weight-derived, diuresis-derived, and spot NaU definition, respectively. The median value of the new NaU-based definition was 31 mmol/40 mg and patients were stratified accordingly. DR patients showed lower cumulative diuresis (5200 mL, 3300-6700 vs 9825 mL, 6200-12200, p = 0.007) and weight loss (4 kg, 1-5 vs 6 kg, 3-8.5, p = 0.023), higher BNP levels (808 pg/mL, 443-1037 vs 351 pg/mL, 209-859, p = 0.062) at the conclusion of protocol-guided i.v diuretic therapy, which was less frequently stopped due to decongestion in DR as compared to non-DR patients (57.7% vs 85.2%, p = 0.026). Six-months mortality or HF hospitalizations were more frequent in DR patients (OR 18.6, 95% CI 2.1-161.2, p = 0.008). CONCLUSIONS: The NaU-based DE definition might solve discrepancies of other previously proposed definitions.

Oral sodium supplementation on growth and hypertension in preterm infants: an observational cohort study.

OBJECTIVE: To evaluate the association between enteral sodium supplementation on growth and hypertension (HTN) in preterm infants. STUDY DESIGN: A retrospective cohort study of infants born between 22-32 weeks and weighing 450-1500 grams (N = 821). Enteral sodium supplementation amounts, systolic blood pressures (SBP), weight gain, and other infant and maternal risk factors for HTN were electronically extracted. RESULTS: Infants receiving sodium supplementation were smaller and less mature. Sodium supplementation improved serum sodium levels, weight gain, and head circumference growth without causing hypernatremia. There was no correlation between urine and serum sodium or urine sodium and weight gain. Although infants receiving sodium had higher average SBP and rates of HTN, analysis demonstrated sodium supplementation did not increase odds of hypertension (ORADJ 1.02;0.64-1.64). Postnatal steroids were associated with HTN. CONCLUSIONS: In preterm infants with poor weight gain, enteral sodium supplementation improved growth without increasing hypertension or hypernatremia.

Maintenance intravenous fluid therapy in infants with sepsis and hyponatremia: a clinical trial.

BACKGROUND: This study aimed to compare the effect of two methods of maintenance intravenous fluid therapy on hyponatremia in hospitalized infants with sepsis. METHODS: In a double-blinded randomized clinical trial, 60 term infants with sepsis were enrolled. Blood samples were taken to determine sodium, potassium, Creatinine, and BUN levels before the initiation of treatment. Urine samples were taken to assess specific gravity and urinary output. Infants in the intervention group received half saline in 10% dextrose and infants in the control group were assigned to receive the conventional solution as maintenance. The above indicators were re-evaluated 24 and 48 h after the initiation of treatment. Two groups were compared concerning the incidence of hyponatremia, and other criteria such as urinary output and urinary specific gravity, blood urea nitrogen (BUN), and creatinine levels. RESULTS: Hyponatremia was more common in the control group. Sodium levels were significantly higher in half saline recipients 24 h (137.83 ± 2.86 vs. 134.37 ± 1.91 mmol/L), and 48 h (138.10 ± 2.41 vs. 133.66 ± 1.98 mmol/L) after treatment (P < 0.001). Although BUN in the intervention group was significantly higher in comparison to the control group, the difference in urinary output, urine specific gravity, potassium, and Creatinine levels were not significant in the two groups. CONCLUSIONS: The use of a half-saline solution as maintenance fluid reduces the risk of hyponatremia after 48 h when compared to 0.18%NaCl. TRIAL REGISTRATION: This has been registered at Iranian Registry of Clinical Trials (Retrospectively registered, Registration date: 2017-10-12, identifier: IRCT2017053034223N1, https://irct.behdasht.gov.ir/trial/26204 ).

Nephrotic syndrome and adrenoleukodystrophy in a 5-year-old boy.

Nephrotic syndrome is a common condition characterized by filtration of large amounts of protein, hypoalbuminemia, reduced plasma oncotic pressure, sodium retention, and edema. The mechanism responsible for sodium retention in this condition is still controversial. Two different pathophysiological pathways have been proposed to explain edema formation: activation of neurohumoral effector mechanisms, including the renin-angiotensin-aldosterone system, or abnormal intrinsic/primary renal sodium retention. A 5-year-old boy with X-linked adrenoleukodystrophy presented with bilateral leg swelling, massive proteinuria, and hypoalbuminemia. Minimal change disease was diagnosed. The patient was initially treated with corticosteroids and experienced several relapses. The progression of fractional excretion of sodium correlated with proteinuria and undetectable aldosterone levels. This unusual finding suggests that the mechanism of tubular sodium avidity in this child with mineralocorticoid insufficiency was independent of the renin-angiotensin-aldosterone system.

The Relationship between Serum Sodium Concentration and Albuminuria: A Retrospective Cohort Study.

BACKGROUND: Lowering dietary salt intake reduces albuminuria, an early marker of renal damage and a sensitive predictor of adverse cardiovascular outcomes. The mechanisms underlying this effect are uncertain but small changes in serum sodium concentration may be important: this retrospective cohort study investigated the hypothesis that higher serum sodium concentration is a risk factor for albuminuria (defined as a urine albumin:creatinine ratio [UACR], ≥3 mg/mmol). METHODS: Primary care data from the Royal College of General Practitioners Research and Surveillance Centre were used to identify 47,294 individuals with a UACR result available between April 2010 and March 2015, and no known albuminuria prior to this. Exclusion criteria were missing or abnormal serum sodium concentration at baseline (<135 or >146 mmol/L); age <18 years; diabetes mellitus; decompensated liver disease; heart failure; and stage 5 chronic kidney disease. RESULTS: After adjustment for known risk factors, there was a significant "U-shaped" relationship between serum sodium concentration and albuminuria. The lowest risk was associated with a serum sodium of 138-140 mmol/L. In comparison, the risk of albuminuria was 18% higher with a serum sodium of 135-137 mmol/L and 19% higher with a serum sodium of 144-146 mmol/L. There was no association between serum sodium concentration and blood pressure. CONCLUSION: The finding of a positive association between higher serum sodium concentration and albuminuria is in support of the hypothesis, but the inverse relationship between serum sodium concentration and albuminuria at lower concentrations warrants further explanation.

Urine sodium concentration and 28-day weight velocity in preterm infants: A retrospective cohort study.

BACKGROUND: Urine sodium concentration has been suggested as a marker to guide enteral sodium supplementation in preterm infants; however, no previous data have demonstrated relationships between urine sodium concentration and postnatal growth. METHODS: We performed a single-center retrospective cohort study on 224 preterm infants admitted to the neonatal intensive care unit at the Children's Hospital of Georgia between January 2010 and July 2022. Spot urine sodium was measured in preterm infants (<34 weeks postmenstrual age [PMA]) between days of life (DOLs) 7 and 28. Our exposure of interest was spot urine sodium concentration (milliequivalents per liter) obtained between postnatal days 7 and 28, and our primary outcome was weight velocity (grams per kilograms per day) determined at DOL 28. Statistical relationships were assessed by multivariate analysis with subgroup comparisons by Student t test and analysis of variance. RESULTS: In 224 preterm infants (199 ± 17 days, 56% male, 71% Black), urine sodium concentration did not associate with weight velocity at DOL 28 and 36 weeks PMA. Urine sodium concentration was weakly associated with gestational age at birth, and Black preterm infants had higher urine sodium values when compared with "other," but not White preterm infants. CONCLUSION: Spot urine sodium during the first month of life does not associate with weight velocity at DOL 28 or 36 weeks PMA.