Sodium Excretion Research Articles (Page 1)

Sodium-glucose co-transporter 2 inhibitors have become a cornerstone in managing chronic heart failure (CHF). While their acute impact on urinary glucose and sodium excretion is well-established, their mid- and long-term persistence of these effects remains uncertain. This study investigated fluid and sodium balance over 3 months in a randomized, placebo-controlled trial (NCT03128528). Overall, 74 patients with New York Heart Association class II-III CHF and an ejection fraction (EF) ≤49% were randomized (2:1) to empagliflozin 10 mg (n = 48) or placebo (n = 26). Sodium, potassium, glucose, urea, and urine were determined from standardized 24-h urine collections. Free water clearance (FWC) and plasma/urine osmolality were calculated. Body weight was measured, and dedicated sodium magnetic resonance imaging (23Na-magnetic resonance imaging) was performed to quantify skin and muscle sodium levels at baseline, at 1 month, and at 3 months. Patients (mean age 66.4 years; 84% male; EF 40%; baseline N-terminal pro-B-type natriuretic peptide 707.9 pg/ml) were followed up at 1 and 3 months. Empagliflozin significantly increased natriuresis at 1 month (p = 0.040), while natriuresis returned to baseline by 3 months. Skin sodium content decreased at 1 month (p = 0.039) and remained reduced at 3 months (p = 0.013), while muscle sodium was unchanged. Persistent glucosuria (p < 0.001) increased urine osmolality at 3 months (p = 0.003). Urine volume increased transiently at 1 month (p = 0.046) but normalized by 3 months. Empagliflozin-treated patients showed a reduction in FWC at 1 and 3 months (p < 0.001), with a compensatory rise in copeptin levels, indicating increased vasopressin activity (1 month: p = 0.020; 3 months: p = 0.001). Mid-range effects of empagliflozin in heart failure with reduced EF include transient natriuresis and sustained glucosuria, with compensatory reductions in FWC. Reductions in skin sodium content were maintained, and volume homeostasis in CHF patients stabilized after 3 months.

Inverse salt sensitivity, an increase in blood pressure (BP) when sodium intake is reduced, affects about 10-15% of the population, yet the mechanisms underlying this alteration in BP are not well understood. The renal dopamine D2 receptor (D2R) plays a critical role in maintaining normal BP and preventing inflammation and tissue injury. The DRD2 is highly polymorphic, and single nucleotide polymorphisms (SNPs) in this gene impair DRD2 synthesis and stability. Specifically, rs6277 SNP in exon 7 of DRD2 is associated with decreased D2R expression and is present in some individuals with hypertension. We have reported that human renal proximal tubular cells with this SNP have decreased D2R mRNA and protein expressions and increased renal Na+ pump/transporter expression. To study the effects of rs6277 on sodium balance and BP, using CRISPR-Cas9, we generated C57Bl/6 mice lacking their own Drd2 but instead express either the human DRD2 wild-type ( DRD2 WT) or rs6277 ( DRD2 Mut). Male and female mice were placed for one week on three distinct salt diets: normal salt (NS; 0.4% NaCl), high salt (HS; 4% NaCl), and low salt (LS; less than 0.08% NaCl) diets. On NS diet, BPs (measured by tail-cuff plethysmography under pentobarbital anesthesia) were slightly higher in male DRD2 Mut than DRD2 WT mice (79±3 vs 73±±0.5 mm Hg; P&lt;0.04; n=5-7/group) while BPs were similar in female DRD2 Mut and DRD2 WT mice (77±3 vs 75±3 mm Hg: n=8/group). On HS diet, BPs were similar in DRD2 WT and DRD2 Mut mice (males 89±2 vs 92±3; females 79±3 vs 87±5 mm Hg). However, on LS diet DRD2 Mut had higher BPs than DRD2 WT mice (males: 72±2 vs 90±2 P&lt;0.001; females: 68±1 vs 88±3 mm Hg, P&lt;0.001). Thus, in DRD2 WT mice, BP increased on HS diet and decreased on LS, while in DRD2 Mut mice, BP increased on both LS and HS diets. There were no significant differences in urinary sodium excretion between DRD2 WT and DRD2 Mut male and female mice on the different diets. These findings suggest that alterations in DRD2 expression/function may be the underlying cause of inverse salt sensitivity of BP because the presence of DRD2 rs6277 is associated with inverse salt sensitivity in mice and humans. Moreover, the increased BP in DRD2 rs6277 mice on LS is independent of urinary sodium excretion.

Background: Adipocytokines leptin from perirenal adipose tissue (PRAT) is implicated in the pathogenesis of obesity-associated hypertension. This study was to demonstrate whether dagliflozin ameliorates renal tubular damage in obese hypertensive mice by reducing leptin from perirenal adipose tissue. Methods: Eight-week-old male C57BL/6 mice were used to establish an obese model by feeding of a high-fat diet for twenty weeks, and then dagliflozin (10mg/kg/d) was intervened for eight consecutive weeks. Human proximal tubular cell line (HK-2) were co-cultured with PRAT conditioned medium (PRAT-CM) with or without dagliflozin and inhibitors. Results: Obese mice exhibited with perirenal adipose tissue accumulation, hypertension, reduced urinary sodium excretion, elevated urinary albumin-to-creatinine ratio. Dagliflozin treatment significantly decreased PRAT-derived leptin secretion and blood pressure, restored impaired urinary sodium excretion, alleviated renal oxidative stress and interstitial fibrosis. Leptin concentration was significantly lower in PRAT-CM from dagliflozin-treated mice than that of obese group. In vitro, dagliflozin inhibited the leptin production and secretion in insulin-resistant 3T3-L1 adipocytes by regulating the PI3K/AKT and ERK1/2 signaling pathways. NADPH oxidase 4 (NOX4) expressions and ROS levels were increased and adenosine 5'-monophosphate-activated protein kinase (AMPK) phosphorylation was decreased in HK-2 cells when co-cultured with PRAT-CM of obese group, accompanied by elevated Na+-K+-ATPase activity, dagliflozin could counteract the pro-sodium uptake effect of PRAT-derived leptin by activating AMPK to inhibit NOX4/ROS/Na+-K+-ATPase oxidative stress amplification loop, and alleviate cell injury in renal tubules. Conclusions: Dagliflozin reduces leptin expression in perirenal adipose tissue and decreases Na+-K+-ATPase activity to increase urinary sodium excretion, lower blood pressure, and ameliorate renal tubular injury.

The dysregulation of renal sodium metabolism linked to obesity and excessive dietary salt intake is a significant factor in the development of salt-sensitive hypertension. Our previous research has demonstrated that oxidative stress-particularly through the amplification loop of reactive oxygen species (ROS)-plays a critical role in modulating renal sodium handling via Na/K-ATPase signaling. This present study aims to determine whether the antioxidant enzyme heme oxygenase-1 (HO-1) modulates renal sodium metabolism by affecting oxidative stress and the Na/K-ATPase pathway, potentially revealing novel therapeutic avenues. To investigate this, we conducted high-salt dietary interventions and administered Co(III) protoporphyrin IX chloride (CoPP) in both normal and obese C57BL/6J mice. Results indicated that obesity exacerbated oxidative stress and disrupted sodium metabolism. Notably, the induction of HO-1 via CoPP effectively reduced oxidative stress, suppressed inflammatory responses, and modulated mechanisms of renal sodium handling. These observations were corroborated by decreases in protein carbonylation and malondialdehyde (MDA) levels, as well as inhibition of the IL-6/STAT3 inflammatory pathway. Importantly, up-regulation of HO-1 corresponded with a reduction in activated Na/K-ATPase signaling, likely attributable to diminished ROS levels. Furthermore, genetic analyses and urinary metabolite profiles validated the regulatory effects of CoPP on oxidative stress and sodium metabolism. In conclusion, our findings elucidate the dual role of HO-1 as both an antioxidant defense system and a pivotal modulator of sodium excretion. This research underscores the multifaceted physiological functions of HO-1 and its crucial role in regulating renal sodium metabolism, with significant implications for managing salt-sensitive hypertension.

Hyponatremia can occur in endocrinological diseases, neoplasms, kidney diseases,and acquired or genetically conditioned disorders of antidiuretic hormone levels.Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a rare X-linked disease caused by a point mutation of the type 2 vasopressin receptor (AVPR2) gene. This mutation results in constitutive activation of the AVPR2 and a low sodium level.We reported the first familial NSIAD in Poland in siblings with hyponatremia.Case 1. A 2.5-year-old boy, during a respiratory tract infection, showed the following laboratory test results: Na 125 mmol/L, serumosmolality 260 mOsm/kg H2O, low uric acid level, and increased fractional sodium and uric acid excretions. Thyroid, adrenal,and renal function were normal. Copeptin level was low.Case 2. A 7-month-old brother presented with reduced activity and muscle tone, a sodium level of 117 mmol/L, and a serum osmolality of 249 mOsm/kg H2O.They were both confirmed to be hemizygous for the R137C mutation on the AVPR2gene.The boys were advised to restrict their oral fluid intake and supplement sodium orally,aiming for sodium levels of 133-140 mmol/L.Conclusions: Genetic testing for an AVPR2 mutation is crucial in patients with hyponatremia, normovolemia, hypoosmolality, and low copeptin level.

Frailty, a geriatric syndrome marked by reduced physiological reserves, has been linked to organ dysfunction. However, the specific contribution of kidney function to frailty remains underexplored. This study aims to assess the impact of kidney function on frailty in a large population of older adults. The FRASNET cohort, including elderly, non hospitalized individuals, was evaluated for frailty, markers ofkidney, glomerular, and tubular function, and for anthropometric parameters. We included 1183 individuals in this study (59.9% females, age 65-93). Among them, 27.7% of subjects were classified asrobust, 37.6% were pre-frail, and 34.7% were frail. The prevalence of frailty increased with age (43% in individuals over 76years of age) and was associated with obesity (28.3%) and polytherapy (23.2%). Whole estimated glomerular filtration rate (eGFR) was 73.8 (IQR 62.4, 84.7) ml/min/1.73m2. The prevalence of chronic kidney disease (CKD) increased across frailty classes from 15.2% in robust to 29.0% in frail individuals (P < 0.001). Among young-old subjects (65-75years old), comorbidity was the main determinant of frailty, whereas in older subjects, when eGFR was below 53.5ml/min/1.73m2, it was associated with frailty (P < 0.002). Fractional excretion of sodium progressively increased across frailty classes, from 0.71% in robust individuals (IQR 0.46-1.03) to 0.79% in frail subjects (IQR 0.48-1.17) (P = 0.04). This study revealed a strong relationship between CKD and frailty, identifying a new eGFR threshold associated with frailty in older adults. The alterations in age- and frailty-dependent sodium handling highlight the potential role of the often-overlooked tubular function in older individuals.

Abstract Background Cystinuria is a rare autosomal recessive disorder characterized by impaired renal reabsorption of cystine and dibasic amino acids, leading to recurrent nephrolithiasis. While dietary salt and protein restriction are commonly recommended, evidence supporting their effectiveness in reducing urinary cystine excretion is limited. This study investigated whether intra-individual changes in dietary salt and protein intake are associated with changes in cystine excretion over time. Methods We conducted a retrospective cohort study of 41 adult patients with recurrent cystine stones treated at a tertiary kidney stone clinic between 2004 and 2023. All patients underwent five 24-hour urine collections at intervals of 6–12 months. Urinary sodium and urea excretions were used as surrogates for salt and protein intake, respectively. Mixed-effects linear regression models assessed within-person associations between dietary intake and urinary cystine excretion, adjusting for age, sex, and time. Results Cystine excretion showed considerable intra-individual variability (intraclass correlation coefficient: 0.457). An increase in urinary urea of 3.5 g/24 h (reflecting ∼10 g/day higher protein intake) was associated with a 164 µmol/24 h increase in cystine excretion (95% CI: 57 to 271, p = 0.003). In contrast, a 17 mmol/24 h increase in urinary sodium (∼1 g/day salt intake) was associated with a non-significant 46 µmol/24 h increase in cystine excretion (95% CI: −5 to 97, p = 0.081). Conclusions Protein intake is moderately associated with urinary cystine excretion, whereas salt intake has minimal effect. These findings suggest that, while protein moderation may contribute to cystine reduction, fluid intake and urine alkalinization remain the primary determinants of urinary cystine levels.

BACKGROUNDAscites is the most common complication of cirrhosis. Current pharmacological interventions, such as diuretics, often become ineffective in advanced stages due to diuretic resistance. Sodium-glucose co-transporter 2 (SGLT2) inhibitors have demonstrated potential in enhancing urinary sodium excretion and mitigating sodium-fluid retention. This study aims to evaluate the effects of SGLT2 inhibitors on the fractional excretion of sodium (FENa) in patients with cirrhotic ascites.AIMTo determine whether adjunctive therapy with the SGLT2 inhibitor empagliflozin increases FENa compared with standard care alone in patients with cirrhosis and refractory ascites, and to evaluate its short-term safety profile.METHODSThe effect of SGLT2 inhibitor empagliflozin on FENa in patients with cirrhosis and refractory ascites is a multicenter, open-label, randomized controlled trial. A total of 70 patients with refractory ascites secondary to cirrhosis will be enrolled and randomly assigned to receive either empagliflozin 10 mg daily plus standard care or standard care alone for 14 consecutive days. The primary outcome is the change in FENa from baseline to day 14. Secondary outcomes include 24-hour urinary sodium excretion, urine volume, ascites volume (assessed by ultrasound), body weight, and safety indicators. Exploratory outcomes include changes in components of the renin-angiotensin-aldosterone system.RESULTSThis article reports the study protocol only. No participant data have been collected or analyzed for this manuscript.CONCLUSIONThis protocol evaluates whether empagliflozin, added to standard therapy, increases sodium excretion and reduces fluid overload in refractory ascites.

Hypothyroidism is associated with the desynchronization of central and peripheral circadian clocks; however, its effects on renal rhythmicity remain unclear. This study investigated the impact of short-term hypothyroidism on renal molecular clock oscillations and daily kidney function in male and female rats. Hypothyroidism was induced by thyroidectomy followed by Methimazole and CaCl2 administration for 21 days. Renal handling of solutes and electrolytes and the expression of core clock components were evaluated every 6h over 24h. Urinary levels of creatinine, protein, glucose, sodium and the clearance and fractional excretion (FE) of these solutes exhibited circadian oscillations in control rats. In males, hypothyroidism abolished the rhythmicity of serum creatinine, creatinine clearance (CCr), renal glucose clearance (Cglucose), and fractional excretion of glucose, sodium, and potassium; decreased the mesor and amplitude of protein excretion parameters; reduced mesor and amplitude of Bmal1 expression and phase advanced Per2 and Nr1d1 mRNA expression. In females, hypothyroidism reduced the mesor of urinary creatinine, serum glucose, and CCr while delaying its acrophase; increased the mesor of proteinuria and glucosuria, and mesor and amplitude of Cglucose and FEglucose; disrupted the circadian pattern of FEproteins and Per2 and Nr1d1 expression in kidney and phase advanced the Bmal1 expression. Sodium and potassium daily handlings were more altered in males than females. No structural damage was found in the kidney of hypothyroid rats. These findings indicate that short-term hypothyroidism desynchronizes the renal circadian clock and disturbs the daily rhythmicity of several renal parameters in a sex-dependent manner, potentially contributing to early-stage kidney dysfunction.

Metabolic syndrome (MetS) is a cluster of metabolic disorders associated with increased risks of cardiovascular diseases and type 2 diabetes, posing a significant public health challenge globally. Early identification of biomarkers for MetS is crucial for timely intervention. This study aimed to explore the association between 24-hour urine indicators (sodium, potassium, creatinine, and microalbumin) and MetS among Chinese adults, providing evidence for early MetS screening and intervention. A cross-sectional survey was conducted in 2017, involving 1175 Chinese residents aged 18–69 years. Data were collected via questionnaires, physical measurements, and laboratory tests, with 24-hour urine samples analyzed for sodium, potassium, creatinine, and microalbumin excretion. Participants were excluded if they had incomplete data, unqualified urine collection, or a self-reported history of hypertension or diabetes. Of the 1175 participants (median age 42 years; 48.17% male), the prevalence of MetS was 11.4%. The median 24-hour urine excretion levels were 158.42/24 hours mmol (sodium), 34.89 mmol/24 hours (potassium), 9.62 mmol/24 hours (creatinine), and 4.31 mg/24 hours (microalbumin). Specifically, 24-hour urine microalbumin excretion was significantly higher in participants with MetS (6.35 mg/24 h) than in those without (4.12 mg/24 h; P < 0.0001), while no significant differences were observed in sodium, potassium, or creatinine excretion between the two groups. Notably, elevated microalbumin excretion was associated with MetS components: central obesity, elevated blood pressure, elevated fasting blood glucose, and elevated triglycerides (all P < 0.05). When microalbumin excretion was divided into quartiles, adjusted odds ratios (adjusted for age, sex, and other confounders) for MetS and its component (elevated fasting blood glucose) increased with higher quartiles (MetS: 1.00, 1.53, 1.99, 2.75; P for trend = 0.0004; elevated fasting blood glucose: 1.00, 1.31, 1.35, 2.20; P for trend = 0.0005). These findings indicate that elevated 24-hour urine microalbumin excretion is independently associated with MetS in Chinese adults, suggesting its potential as a practical biomarker for early risk assessment and intervention.

Abstract Disclosure: A. Tapia-Castillo: None. J.A. Pérez: None. P. Carrión: None. R. Baudrand: None. T. Uslar: None. M. Hernández: None. R. Pinilla: None. A. Martinez: None. C.E. Fardella: None. C.A. Carvajal: None. The nonclassic apparent mineralocorticoid excess (NCAME) is a prevalent endocrine disorder affecting 7% of the population. Characterized by reduced activity of the 11β-hydroxysteroid dehydrogenase type 2 enzyme (11βHSD2), disrupting the balance between cortisol and cortisone, potentially influencing other redox reactions (11-OH &amp;gt;11-Keto) crucial for steroid metabolism. Since endogenous (adrenal and gonadal) and exogenous steroids could be influenced by sex, identification of a sex-specific steroidomic profiles in NCAME, would provide valuable insights associated to the pathophysiologic mechanisms associated to NCAME. Objective: To identify a sex-differentiated steroid profile in subjects with NCAME. Subjects: A cross-sectional study was conducted in a cohort of 41 subjects classified as having NCAME (F/E &amp;gt; 4.1 ug/dl; E &amp;lt; 2.1 ug/dl) and controls. Clinical variables (blood pressure (BP), BMI, % fat, age) and biochemical variables (renin activity (PRA), sodium (Na) and potassium (K) excretion, urinary albumin, and NGAL) were determined. Women using oral contraceptives were excluded. The cohort was dichotomized by sex. Methods: An analysis of 21 steroids was performed using mass spectrometry (UPLC-Q-TOF/MS). Statistical analysis was performed using the Mann-Whitney T-test with Prism v9. Results: 21 subjects with NCAME were identified, of whom 14 were women and 7 were men. No difference in age or percentage of fat was observed between the groups. In women with NCAME, we observed lower PRA (1.4 ± 0.7 vs 1.7 ± 0.4 ng/ml/h; p&amp;lt;0.05), urinary Na/K ratio (2.6 ± 1.2 vs 3.0 ± 0.9; p&amp;lt;0.05), and higher urinary albumin (12.6 ± 6.7 vs 6.0 ± 4.6 mg/24h; p=0.02) and potassium excretion (52 ± 19 vs 32 ± 12 mEq/24h; p=0.02) than in control women. Their steroid profile showed lower levels of cortisone (1.6 ± 0.4 vs 2.5 ± 0.4 ug/dl; p&amp;lt;0.0001), increased 11-hydroxyandrosterone (2.2 ± 0.2 vs 1.9 ± 0.2; p=0.003), and decreased 17-hydroxypregnenolone sulfate (15.5 ± 7.3 vs 25.7 ± 6.0; p=0.002) and 11-oxo-androsterone glucuronide (7.6 ± 2.0 vs 10.5 ± 3.5; p=0.04) than controls.In men with NCAME, we observed higher levels of NGAL (145.8 ± 64 vs 86.6 ± 31 ng/ml; p=0.03), and their steroid profile showed higher levels of cortisol (14.7 ± 4.4 vs 11.1 ± 4.9 ug/dl; p&amp;lt;0.05) and F/E ratio (7.3 ± 2.7 vs 4.4 ± 1.3; p=0.01), and decreased 6β-hydroxycortisol (4.6 ± 1.7 vs 11.0 ± 4.2; p=0.01). Conclusion: This study provides novel insights into the sex-dependent biochemical and steroidomic signatures of NCAME. The identification of 11-hydroxyandrosterone as a key player in female NCAME suggests that this metabolite could act as an endogenous inhibitor and could modulate the activity of the 11βHSD2 enzyme, support the development of innovative biomarkers and personalized interventions for NCAME. Presentation: Monday, July 14, 2025

Different measures of sodium intake and the risk of metabolic dysfunction-associated steatotic liver disease: Evidence from the UK Biobank.

Abstract Disclosure: E. Ng: None. H.Q. Shen: None. X. Lim: None. P. Marcus: None. S.M. Gwini: None. M. Thuzar: None. M. Stowasser: None. P.J. Fuller: None. J. Hu: None. J. Yang: None. In primary aldosteronism (PA), the variability in plasma aldosterone concentration (PAC) at a single time point is well documented. Measurement of 24-hour urinary aldosterone excretion (24h-UAE) may overcome this variability. An elevated 24h-UAE &amp;gt; 12 ug (33 nmol)/day, combined with high urinary sodium excretion (24h-UNa) &amp;gt; 200 mmol/day, is a recognised method for confirming PA. However, the rationale for this threshold and its diagnostic accuracy are not well established. This study aims to assess the diagnostic accuracy of the historical cut-off in Australian and Chinese cohorts and evaluate the optimal 24h-UAE threshold for diagnosing PA, using the saline suppression test (SST) as the reference standard. Patients referred for PA workup from 2018 to 2023 at two tertiary centres in Melbourne, Australia (n=215), and Chongqing, China (n=894) were included in the study if they had a 24h-UAE and SST performed. Blood and urine collections for aldosterone measurements were performed after washout of interfering medications. 24h urine sample collection was performed in an ambulatory setting for the Australian cohort and in an inpatient setting for the Chinese cohort. PAC, DRC and 24h-UAE were measured using an automated chemiluminescence immunoassays (DiaSorin). The diagnostic accuracy of 24h-UAE was compared to the SST result. The optimal 24h-UAE was determined using the Liu optimal cut-point and Youden index. PA was diagnosed in 138/215 (64%) of the Australian and 688/894 (77%) of the Chinese cohorts based on SST. The 24h-UAE cut-off of &amp;gt; 33 nmol/day (regardless of 24h-UNa) demonstrated 53% sensitivity and 79% specificity in the Australian cohort, and 36% sensitivity and 93% specificity in the Chinese cohort. The addition of 24h-UNa &amp;gt; 200 mmol/day improved sensitivity to 57 and 41%, respectively, but reduced specificity in the Australian cohort (75%), with no change in the Chinese cohort. In the Australian cohort, where 24h-UNa &amp;gt;190 mmol/day, the optimal 24h-UAE threshold was &amp;gt; 31 nmol/day, yielding 64% sensitivity and 77% specificity for diagnosing PA. In those with a DRC &amp;lt; 10 mU/L and 24h-UNa &amp;gt;190 mmol/day, a 24h-UAE &amp;gt; 22 nmol/day achieved 76% sensitivity and 83% specificity. Comparable diagnostic accuracy was seen in the Chinese cohort with the same DRC and 24h-UNa cut-off at a lower 24h-UAE cut-off of &amp;gt;18 nmol/day. This study highlights the suboptimal diagnostic accuracy of 24h-UAE measured by immunoassay and challenges the validity of the historical 24h-UAE cutoff of 33 nmol/day. Utility of the 24h-UAE may be improved by using liquid chromatography-mass spectrometry to measure aldosterone, but this remains to be formally evaluated. Presentation: Saturday, July 12, 2025

Pharmacologically induced diuresis in the treatment of acute heart failure (AHF) is commonly assessed using clinical congestion scores or daily weight monitoring, but these methods may lack precision due to examiner subjectivity and variability in weight fluctuations. The European Society of Cardiology recommends measuring natriuresis to evaluate the diuretic response and adjust the dosage accordingly. Higher natriuresis has been associated with better clinical outcomes following an episode of AHF in observational studies. Recent prospective trials have shown that a natriuresis-guided strategy increases cumulative sodium excretion and shortens hospital stay without impacting clinical outcomes. Its routine implementation is limited by the practical challenges associated with standardized urine sampling.

Abstract Background and Aims Sodium-glucose co-transporter inhibitors (SGLT2i) have emerged as a cornerstone therapy for diabetes mellitus and, more recently, for cardiovascular diseases. Large clinical trials have demonstrated the remarkable benefits of SGLT2i on renal and cardiovascular outcomes. Recently, the dual SGLT1/2 inhibitor sotagliflozin received FDA approval for the treatment of heart failure regardless of ejection fraction, highlighting its potential broad applicability. Despite these promising findings, the molecular mechanisms mediating the effects of SGLT inhibitors, particularly in the context of salt-sensitive hypertension, remain underexplored. The primary objective of this study was to investigate the effects of SGLT inhibition on the development of salt-induced hypertension and to elucidate the underlying mechanisms contributing to these effects. Method Dahl salt-sensitive (SS) rats, a well-established model of salt-induced hypertension, were used to evaluate the effects of SGLT2 and dual SGLT1/2 inhibitors, dapagliflozin (Dapa) and sotagliflozin (Sota), respectively. Eight-week-old male SS rats were treated with or without Dapa (2 mg/kg/day in drinking water) or Sota (30 mg/kg/day in food) for 3 weeks. To investigate potential molecular mechanisms underlying the beneficial effects of SGLT2 inhibition, additional analyses were performed on tissues collected from SS rats fed a high-salt (HS) diet and treated with either vehicle or Dapa. The effects of Dapa on renal sodium channels and transporters were assessed using RT-PCR, Western blot analysis, and patch clamp techniques. Transcriptomic analyses and lipid mediator profiling were conducted in the kidney cortex of male SS rats on a 3-week HS diet with or without Dapa treatment to further explore the metabolic impacts of SGLT2 inhibition. Results Administration of dapagliflozin (Dapa) mitigated the development of salt-induced hypertension in both male and female Dahl SS rats, as demonstrated by lower blood pressure and a leftward shift in the pressure-natriuresis curve (Kravtsova et al., AJP: Renal, 2022; Kravtsova et al., Sci Rep, 2023). However, neither mRNA nor protein expression levels of key renal transporters, such as SGLT2, NHE3, NKCC2, NCC, and α-, β-, and γ-ENaC subunits, showed significant differences between groups. Additionally, electrophysiological experiments indicated no significant effects of Dapa on the conductance or activity of ENaC. Dual SGLT1/2 inhibition with Sota effectively prevented the development of salt-sensitive hypertension in both male and female Dahl SS rats without affecting heart rate. By the 21st day of the HS challenge, mean arterial pressure was reduced by more than 30 mmHg in Sota-treated groups compared to vehicle controls. Sota treatment significantly increased diuresis, glucose excretion, and sodium excretion in both sexes. Despite these effects, no changes in kidney weight or glomerular filtration rate and creatinine clearance were detected. However, Sota treatment reduced the heart-to-body weight ratio, attenuated kidney fibrosis, decreased protein cast formation, and lowered albuminuria. Conclusion This study demonstrates that SGLT2 and SGLT1/2 inhibition in a nondiabetic model of salt-sensitive hypertension attenuates the development and severity of salt-induced hypertension. Chronic SGLT2 inhibition enhances glucose and sodium excretion without impacting the expression or function of other sodium transporters and channels along the nephron or altering hormone levels in the renin-angiotensin-aldosterone system. Transcriptomic analyses of the kidney cortex identified lipid and amino acid metabolism, molecular transport, and cell function as the top biological pathways influenced by SGLT2 inhibition. Furthermore, dual SGLT1/2 inhibition provided even higher protection against salt-sensitive hypertension and associated kidney damage compared to SGLT2 inhibition alone.

Abstract Background and Aims The Mediterranean diet has been shown to benefit cardiovascular risk, weight management, visceral fat reduction, cognitive function, and protection against non-communicable chronic diseases. This study aimed to evaluate the effectiveness and appropriateness of the Mediterranean diet combined with exercise for patients with chronic kidney disease (CKD). Method Patients with CKD attending the Nephrology Clinic of the University Medical Center Ljubljana were included in the study. Compliance with the Mediterranean diet was assessed using a food frequency questionnaire and the 14-point Mediterranean Diet Adherence Screener (14-MEDAS), which offers a quick evaluation of dietary habits and their alignment with Mediterranean principles. Participants followed a 4-week intervention consisting of the Mediterranean diet and regular exercise. Baseline assessments included a 1-day food diary, anthropometric measurements, muscle strength evaluation (via a palm squeeze and sit-up test), and biochemical analysis of blood and urine parameters. Results A total of 28 CKD patients (grades 1-4) were selected from an initial cohort of 199 patients. After receiving instructions on the Mediterranean diet and exercise, along with written guidelines, the average MEDAS score increased significantly from 6.36 to 9.86 points (P &amp;lt; 0.001) following the 4-week intervention. Fiber intake increased significantly (from 24 g to 35 g daily, P &amp;lt; 0.01), while protein and carbohydrate intake also rose, and fat intake decreased, although these changes were not statistically significant. There was a trend toward weight loss (P = 0.07) and reduction in waist circumference (P = 0.08). Serum potassium, phosphate, and bicarbonate concentrations remained unchanged despite the increase in dietary fibre. Serum LDL cholesterol significantly decreased (from 3.4 to 2.7 mmol/L, P = 0.01), while vitamin D levels increased (from 58 to 77 nmol/L, P = 0.02), and sodium excretion in 24-hour urine decreased significantly (from 206 to 145 mmol/day, P = 0.02). While the results of the sit-up test showed improvement, the change was not statistically significant. Conclusion The significant improvement in the MEDAS score after the 4-week intervention suggests that even a short-term dietary and exercise program can lead to healthier eating habits. The intervention also resulted in beneficial effects on body weight, waist circumference, sodium intake, LDL cholesterol levels, and vitamin D status. Our findings indicate that the Mediterranean diet and exercise are highly suitable for CKD patients, offering potential long-term health benefits with minimal side effects.

Abstract Background and Aims Low potassium intake is common in kidney transplantation recipients (KTRs). Previous cohort studies suggested that low potassium intake is associated with an increased risk of death-censored graft failure (DCGF) and all-cause mortality. However, these studies estimated potassium intake using single 24-hour urinary potassium excretion (UKV) measurements. Because potassium excretion is highly variable over time, baseline UKV may inaccurately represent long-term potassium intake. Therefore, we aimed to investigate whether using single baseline vs. repeated UKV measurements to estimate potassium intake impacts the association between estimated potassium intake and outcomes after kidney transplantation. Method We performed a retrospective analysis of a single-center cohort, consisting of KTRs with available outpatient clinic 24 h UKV measurements collected between 1980 and 2016. To control for potential urine collection errors, we removed the 5% of measurements with the largest difference between expected and collected 24 h urine volumes. Baseline potassium intake was estimated from each participant's first available outpatient clinic UKV measurement after transplantation. Long-term potassium intake was estimated using a time-weighted average of all available UKV measurements. Co-primary outcomes were all-cause mortality and death-censored graft failure. Statistical analysis consisted of Cox regression analyses adjusted for sex, age, BMI, smoking, systolic and diastolic blood pressure, number of antihypertensives, eGFR, proteinuria, and urinary sodium and urea excretion. Models with time-weighted potassium intake also included time-weighted averages of urinary sodium excretion. Results The cohort consisted of 1478 KTRs (mean age 44.7 ± 13.6 yr, 44.6% male) with a total of 10,418 twenty-four-hour urine samples (median 3 [IQR 2–8] samples per person. In the study population, mean potassium intake was similar when using baseline (3.47 ± 1.34 g/d) and time-averaged UKV (3.53 ± 1.30 g/d; Fig. 1). During a median follow-up of 13.8 [IQR 7.7–20.8] yr, 732 (49.5%) patients died and 395 (26.7%) developed DCGF. After adjustment for potential confounders, a higher time-averaged potassium-intake was associated with a significantly lower risk of graft failure (HR 0.76 [95% CI 0.64–0.90], P = 0.0015; Table 1), while a single baseline UKV was not (HR 0.90 [0.77–1.05], P = 0.17). Similarly, a higher time-averaged potassium intake was associated with a significantly lower risk of all-cause mortality (HR 0.83 [0.74–0.93], P = 0.0019), while a single baseline UKV was not (HR 0.91 [0.81–1.02], P = 0.11). Conclusion Higher long-term potassium intake after transplantation was associated with a reduced risk of graft failure and all-cause mortality. Conversely, a single estimation of potassium intake was not associated with outcomes. These results stress that preferably, repeated 24 h urine collections should be used to adequately assess the relationship between potassium intake and clinical outcomes.

Abstract Background and Aims Renewed interest in the physiological role of ketone bodies (KB) has emerged. Several beneficial effects are related to ketosis including improved exercise capacity and improved cardiac function. Animal studies have suggested that ketosis is renoprotective due to anti-inflammatory and anti-fibrotic effects. However, only few clinical studies have examined renal effects of ketosis, and there is a paucity of clinical studies investigating the effects of ketosis on sodium- and water balance. We aimed to examine the effects of exogenous ketosis on renal function and sodium excretory capacity in healthy subjects. Method We conducted a randomized, placebo-controlled, double-blinded, crossover study. Sixteen healthy participants received a ketone monoester drink and a placebo drink three times a day for five days in a randomized order. There was a washout period for two weeks in between each treatment period. The participants followed a standardised diet during the study periods. At the end of each treatment period, we performed a 99mTc-DTPA-clearance estimation to determine glomerular filtration rate (GFR) along with fractional excretion of sodium (FENa), and fractional excretion of potassium (FEK+). We also performed a 24-hour ambulatory blood pressure measurement including a cuff-based determination of vascular stiffness and peripheral resistance. We employed a linear mixed model to analyze the effect of ketosis on GFR and sodium excretion incorporating treatment, time and treatment sequence as fixed effects and participant ID as random effect. The models were checked for a treatment-by-time interaction. Results Thirteen healthy participants completed both study periods. Baseline characteristics are displayed in Table 1. Intake of ketone monoester drink successfully increased plasma concentration of beta-hydroxybutyrate above 2 Mmol/L half an hour after intake. Ketosis significantly increased GFR compared with placebo resulting in a mean difference of 6 mL/min (95% CI: 2.4, 9.7; P = 0.007). Also, ketosis increased FENa with a mean difference of 0.4% (95% CI: 0.23, 0.55; P &amp;lt; 0.001). FEK+ was significantly decreased with a mean difference of −7.9% (95% CI: −10.1, −5.7; P &amp;lt; 0.001) during ketosis. There was no change in systolic or diastolic blood pressure. However, peripheral vascular resistance was decreased with a mean change of −49 dyn*s/cm5 (95% CI: −95, −3; P = 0.04) while heart rate was increased by 9% (95% CI: 4, 14; P = 0.002). Conclusion Ketosis increases GFR and sodium excretion, whilst decreasing potassium excretion. Furthermore, ketosis reduces peripheral vascular resistance. The findings suggest potential advantages for kidney health, but further research is needed to assess its therapeutic efficacy in chronic kidney disease prior to formulating clinical recommendations.

Abstract Background and Aims Sodium glucose cotransporter 2 inhibitors (SGLT2i) exert cardiovascular and renal benefits in type 2 diabetes mellitus (DM2) and chronic kidney disease (CKD), potentially mediated in part by natriuresis and changes in fluid balance. However, the exact mechanisms are not fully clear. We examined the effects of empagliflozin on fluid and electrolyte balance in a cohort of patients with DM2 and preserved kidney function (estimated glomerular filtration rate (eGFR) &amp;gt;60 ml/min/1.73 m2), DM2 and concomitant CKD and non-diabetic CKD (both eGFR 20–60 ml/min/1.73 m2), respectively. Method A randomized double blind, placebo controlled cross-over trial. Participants were randomized to 4 weeks of empagliflozin 10 mg/day or matching placebo and crossed over to 4 weeks of the opposite treatment after a wash out. We measured body composition by bio-impedance using a Fresenius Body Composition Monitor, 24-hour ambulatory blood pressure (BP) using a Mobil-O-Graph, urinary sodium, potassium and glucose excretion, free water clearance, plasma levels of renin, aldosterone and copeptin and urinary excretion of epithelial sodium channels (ENaC), aquaporin-2 (AQP2) and sodium-chloride cotransporter (NCC). Results 49 participants completed the trial, 16 with DM2 and preserved renal function, 17 with DM2 and CKD and 16 with non-diabetic CKD. Mean age was 68, 8 ± 7.5 years, median eGFR was 42.2 ml/min/1.73 m2 (interquartile range: 34.5–73.5). 73% were male, 92% had concomitant arterial hypertension and 20% had ischemic heart disease. Empagliflozin reduced extracellular body water by 0.29 L (95% CI: −0.54; −0.03 L, P = 0.03) and tended towards reducing overhydration (mean difference: −0.23L, 95% CI: −0.51; 0.05L, P = 0.10). Systolic BP decreased by 6 mmHg and diastolic BP decreased by 3 mmHg during empagliflozin treatment compared to placebo (P &amp;lt; 0.001). Change in overhydration was correlated to changes in systolic BP (R = 0.38, P = 0.008). Sodium excretion and urine volume did not change, but empagliflozin increased glucose excretion (P &amp;lt; 0.0001) and fractional potassium excretion (P = 0.046). Furthermore, copeptin levels increased by 30% (P &amp;lt; 0.0001), urinary AQP2 excretion increased by 8% (P = 0.04) and free water clearance decreased (P = 0.0001). Renin levels also increased (P = 0.02) and there were borderline significant rises in aldosterone (P = 0.05) and urinary ENaC excretion (P = 0.08). Urinary excretion of NCC did not change (P = 0.63) Conclusion Our results indicate that SGLT2i exert a diuretic effect which, although compensated by increased activity of the renin-angiotensin system and antidiuretic hormone, leads to changes in fluid balance. Furthermore, the BP lowering effect of SGLT2i may be related to changes in fluid balance.

Abstract Background and Aims Lifestyle factors as contributors to cardiovascular disease has been the focus of attention in recent years. Dietary sodium intake is a known risk factor to high blood pressure (BP) and thus cardiovascular disease. Several studies have shown a blood pressure decreasing effect of reducing dietary sodium however only few of these studies examined self-performed sodium reduction. Instead, they used hand-out low-sodium diets and results from these are therefore sparsely transferable to a real-life setting. Additionally, knowledge on the underlying physiology of the BP response is still lacking. This study aimed to test the effects of a self-performed dietary sodium reduction on BP in patients with essential hypertension and examine the effects on the renin-angiotensin-aldosterone system. Method A randomised, non-blinded clinical trial including 72 patients with hypertension was conducted. Participants were randomized 2:1 to either self-performed sodium reduction or a control group for a study period of four weeks. Both oral and written advice on lowering sodium intake was provided to the intervention group. Blood samples, 24-hour urine collection and 24-hour ambulatory BP measurements were performed before and after the intervention. Results Urinary 24-hour sodium excretion decreased 66 mmol (95% CI −96; −37 mmol) in the intervention group compared to the control group, which attained no significant change (5 mmol, 95% CI −12; 21 mmol). Systolic 24-hour BP decreased 9 mmHg after low-sodium diet compared to the control group (95% CI −13; −4 mmHg). Similarly, the difference in reduction in diastolic BP between the groups was 5 mmHg (95% CI −8; −1 mmHg) Plasma levels of renin increased significantly in the intervention group compared to the control group (median change 6.8 pg/ml vs. 0.0 pg/ml, P &amp;lt; 0.0005). Likewise, did we find an increase in plasma aldosterone in the intervention group with a mean difference of 37.68 pg/ml compared to the control group (95% CI 17.34; 58.01, P = 0.0004) An association between change in aldosterone levels and change in BP was found (P = 0.005), however we did not find this association for renin and BP. Neither changes in renin nor aldosterone were associated to the reduction in sodium excretion. Conclusion A self-performed dietary sodium reduction of 66 mmol/day led to a decrease in 24-hour BP of 9/5 mmHg compared to a control group. Plasma renin and plasma aldosterone levels increased significantly compared to a control group, likely as a compensatory mechanism. The change in BP was related to the change in plasma aldosterone. Advice on how to lower sodium intake as part of treatment of patients with essential hypertension could lead to better blood pressure control and thus lower risk of cardiovascular disease.