Hyponatremia and Oxidative Stress

The relationship between hyponatremia and mortality in patients receiving nutrition support

BACKGROUND & AIMS

Hyponatremia is frequently seen in clinical practice, but most cases are mild and asymptomatic and therefore often go unmanaged. In recent years, it has been reported that the onset or improvement of hyponatremia, even in mild cases, has an impact on mortality and that hyponatremia is directly related to increased mortality. In addition, it has been reported that patients with Nutrition Support Team (NST) are more likely to develop hyponatremia than the general hospitalized population. This study aimed to determine the association between the development and amelioration of hyponatremia and mortality in patients with NST.

METHODS

A total of 1553 patients who underwent initial NST intervention from April 1, 2013 to March 31, 2017 were included. Hyponatremia was defined as hyponatremia <138 mEq/L and normal serum sodium level was defined as 138-145 mEq/L based on the laboratory reference values of our hospital. Hyponatremia was defined as L and normal sodium as N. Based on sodium levels at the start and end of the intervention, the population was classified into four groups, L-L, N-L, L-N, and N-N (sodium level at the start of intervention - sodium level at the end of intervention), and the 5-year survival rate curve and hazard ratio for death for each group were calculated. Multivariate analysis adjusted for age, sex, and body mass index.

RESULTS

Analysis revealed that the L-L group with persistent hyponatremia (hazard ratio (HR) = 3.47, vs N-N, p < 0.0001) had the highest risk of death, while the L-N group with improved hyponatremia (HR = 2.19, vs N-N, p < 0.0001) had a significantly lower risk than the L-L group. The risk of death was also increased in the L-N and N-L groups (HR = 1.97, vs. N-N, p << 0.0001) after even one episode of hyponatremia compared to the N-N group.

CONCLUSION

The results of this study indicate that hyponatremia is associated with poor survival in patients undergoing NST. Future randomized controlled trials are needed to determine whether correction of hyponatremia leads to improved survival in patients undergoing NST to clarify the need for prevention and management of hyponatremia.

Correction Rates and Clinical Outcomes in Hospitalized Adults With Severe Hyponatremia: A Systematic Review and Meta-Analysis

Importance

Hyponatremia treatment guidelines recommend limiting the correction of severe hyponatremia during the first 24 hours to prevent osmotic demyelination syndrome (ODS). Recent evidence suggests that slower rates of correction are associated with increased mortality.

Objective

To evaluate the association of sodium correction rates with mortality among hospitalized adults with severe hyponatremia.

Data Sources

We searched MEDLINE, Embase, the Cochrane Library, LILACS, Web of Science, CINAHL, and international congress proceedings for studies published between January 2013 and October 2023.

Study Selection

Comparative studies assessing rapid (≥8-10 mEq/L per 24 hours) vs slow (<8 or 6-10 mEq/L per 24 hours) and very slow (<4-6 mEq/L per 24 hours) correction of severe hyponatremia (serum sodium <120 mEq/L or <125 mEq/L plus severe symptoms) in hospitalized patients.

Data Extraction and Synthesis

Pairs of reviewers (N.A.F., J.R.M., J.M.A., A.C.) independently reviewed studies, extracted data, and assessed each included study's risk of bias using ROBINS-I. Cochrane methods, PRISMA reporting guidelines, and the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach to rate the certainty of evidence were followed. Data were pooled using a random-effects model.

Main Outcomes and Measures

Primary outcomes were in-hospital and 30-day mortality, and secondary outcomes were hospital length of stay (LOS) and ODS.

Results

Sixteen cohort studies involving a total of 11 811 patients with severe hyponatremia were included (mean [SD] age, 68.22 [6.88] years; 56.7% female across 15 studies reporting sex). Moderate-certainty evidence showed that rapid correction was associated with 32 (odds ratio, 0.67; 95% CI, 0.55-0.82) and 221 (odds ratio, 0.29; 95% CI, 0.11-0.79) fewer in-hospital deaths per 1000 treated patients compared with slow and very slow correction, respectively. Low-certainty evidence suggested that rapid correction was associated with 61 (risk ratio, 0.55; 95% CI, 0.45-0.67) and 134 (risk ratio, 0.35; 95% CI, 0.28-0.44) fewer deaths per 1000 treated patients at 30 days and with a reduction in LOS of 1.20 (95% CI, 0.51-1.89) and 3.09 (95% CI, 1.21-4.94) days, compared with slow and very slow correction, respectively. Rapid correction was not associated with a statistically significant increased risk of ODS.

Conclusions and Relevance

In this systematic review and meta-analysis, slow correction and very slow correction of severe hyponatremia were associated with an increased risk of mortality and hospital LOS compared to rapid correction.

Effects of Reduced Extracellular Sodium Concentrations on Cisplatin Treatment in Human Tumor Cells: The Role of Autophagy

Hyponatremia is the prevalent electrolyte imbalance in cancer patients, and it is associated with a worse outcome. Notably, emerging clinical evidence suggests that hyponatremia adversely influences the response to anticancer treatments. Therefore, this study aims to investigate how reduced extracellular [Na+] affects the responsiveness of different cancer cell lines (from human colon adenocarcinoma, neuroblastoma, and small cell lung cancer) to cisplatin and the underlying potential mechanisms. Cisplatin dose-response curves revealed higher IC50 in low [Na+] than normal [Na+]. Accordingly, cisplatin treatment was less effective in counteracting the proliferation and migration of tumor cells when cultured in low [Na+], as demonstrated by colony formation and invasion assays. In addition, the expression analysis of proteins involved in autophagosome-lysosome formation and the visualization of lysosomal areas by electron microscopy revealed that one of the main mechanisms involved in chemoresistance to cisplatin is the promotion of autophagy. In conclusion, our data first demonstrate that the antitumoral effect of cisplatin is markedly reduced in low [Na+] and that autophagy is an important mechanism of drug escape. This study indicates the role of hyponatremia in cisplatin chemoresistance and reinforces the recommendation to correct this electrolyte alteration in cancer patients.

Hyponatremia and takotsubo syndrome: a review of pathogenetic and clinical implications

Hyponatremia is a common electrolyte abnormality with important prognostic and therapeutic implications. It might exert detrimental effects on various organ systems including the central nervous system (CNS), bone, and heart along with its potential association with poor quality of life. These adverse effects might be largely mediated through a variety of mechanisms including osmotic stress, dysfunctional transmembrane exchangers, and enhanced oxidative stress.Interestingly, hyponatremia might also have an important association with takotsubo syndrome (TTS) that has been universally considered as a reversible form of cardiomyopathy usually emerging in response to various stressors. In this context, severe hyponatremia was previously reported to serve as a direct trigger of TTS evolution largely through its potential impact on CNS and heart. However, pathogenetic and clinical implications of hyponatremia still need to be thoroughly evaluated in patients with TTS. This paper aims to analyze the clinical features of published cases with TTS primarily triggered by hyponatremia and also aims to discuss the association between hyponatremia and TTS from a broader perspective.

The Antioxidant Activities In Vitro and In Vivo and Extraction Conditions Optimization of Defatted Walnut Kernel Extract

The objective of this study was to determine the antioxidant activities of defatted walnut kernel extract (DWE) and whole walnut kernel extract (WE) in vitro and in vivo. Three spectrophotometric methods, DPPH, ABTS, and FRAP, were used in in vitro experiments, and mice were used in in vivo experiments. In addition, response surface methodology (RSM) was used to optimize reflux-assisted ethanol extraction of DWE for maximum antioxidant activity and total phenolic content. The results of in vitro experiments showed that both extracts showed antioxidant activity; however, the antioxidant activity of DWE was higher than that of WE. Both extracts improved the mice's oxidative damage status in in vivo studies. An ethanol concentration of 58%, an extraction temperature of 48 °C, and an extraction time of 77 min were the ideal parameters for reflux-assisted ethanol extraction of DWE. The results may provide useful information for further applications of defatted walnut kernels and the development of functional foods.

Hyponatremia-related liver steatofibrosis and impaired spermatogenesis: evidence from a mouse model of the syndrome of inappropriate antidiuresis

PURPOSE

Hyponatremia is the most frequent electrolytic disorder in clinical practice. In addition to neurological symptoms, hyponatremia, even when mild/moderate and chronic, has been related to other manifestations, such as bone demineralization and increased risk of fractures. To better elucidate tissue alterations associated with reduced serum sodium concentration [Na⁺], we developed an in vivo model of hyponatremia secondary to the Syndrome of Inappropriate Antidiuresis.

METHODS AND RESULTS

Hyponatremia was induced in Foxn1^nu/nu mice by subcutaneous infusion of the vasopressin analog 1-deamino [8-D-arginine] vasopressin (dDAVP) for 14 days via osmotic mini-pumps. Mice in the control group were infused with isotonic saline solution. Serum [Na⁺] progressively decreased, with a nadir of 123.4 ± 2.3 mEq/L (mean ± SD, dDAVP 0.3 ng/h) and 111.6 ± 4.7 mEq/L (mean ± SD, dDAVP 0.5 ng/h). Evident signs of liver steatofibrosis were observed at histology in hyponatremic mice. Accordingly, the expression of proteins involved in lipid metabolism (SREBP-1, PPARα and PPARγ) and in myofibroblast formation (αSMA and CTGF) significantly increased. Furthermore, heme oxygenase 1 expression was up-regulated in Kupffer and hepatic stellate cells in the liver of hyponatremic mice. Testis alterations were also observed. In particular, the thickness of the seminiferous epithelium appeared reduced. The expression levels of PCNA and PTMA, which are involved in DNA replication and germ cells maturation, were markedly reduced in the testis of hyponatremic mice.

CONCLUSION

Overall, these findings shed new light on the possible consequences of chronic hyponatremia and prompt a more thorough evaluation of hyponatremic patients.

Oxidative Stress and Inflammation as Targets for Novel Preventive and Therapeutic Approaches in Non-Communicable Diseases II

Non-communicable diseases (NCDs) are non-infectious chronic pathologies—including obesity, metabolic syndrome, chronic kidney disease (CKD), cardiovascular (CV) diseases, cancer, and chronic respiratory diseases—which represent the main cause of death and disability for the general population [...]