Hyponatremia: A practical approach

Effect of Two Hydration Strategies on CapillarySodium Concentrations in Runners Participating in 170-km Trail Race: The 2015 UltraTrail du Mont-Blanc Experience

OBJECTIVE

This study assessed the impact of 2 hydration strategies on capillary sodium concentrations during Ultra-Trail du Mont-Blanc (UTMB) 2015.

DESIGN

Prospective exposed/nonexposed cohort study.

SETTING

Ultra-Trail du Mont Blanc 2015 (170 km).

PARTICIPANTS

Thousand five hundred sixty-three registered runners of UTMB 2015 asked to predefine their hydration strategy as either "drinking to thirst" or any other mode ("not drinking to thirst").

INTERVENTION

One hundred "drinking to thirst" participants were randomly selected and paired (sex and age) with 96 "not drinking to thirst" participants. Participant weight and capillary sodium concentrations were measured before and after the race.

MAIN OUTCOME MEASURES

Variations of capillary sodium concentrations and weight during the trail according to predefine hydration strategy as either "drinking to thirst" or "not drinking to thirst." Adverse events were recorded. P < 0.05 was considered statistically significant.

RESULTS

Among 196 participants, 88 (62 finishers) "drinking to thirst" and 87 (64 finishers) "nondrinking to thirst" participants were analyzed, respectively. There was no difference in the change in capillary sodium concentrations prerace to postrace between the groups (1.5 ± 4.4 vs 1.5 ± 4.7 mEq/L, P = 0.98). The change in participant weight was also not different (P = 0.3877). Hypernatremia or hyponatremia were reported in 19 of 88 (21.6%) and 24 of 87 (27.6%) in "drinking to thirst" and "non-drinking to thirst" participants, respectively (P = 0.20). The incidence of adverse events was not different between the groups.

CONCLUSION

This study observed no impact of hydration strategy on the change in capillary sodium concentrations before and after UTMB 2015.

2024 AAHA Fluid Therapy Guidelines for Dogs and Cats

Fluids are drugs used in veterinary patients capable of producing beneficial therapeutic or inadvertent harmful effects within the body's intravascular, interstitial, and intracellular fluid spaces. The individualized design of a fluid therapy plan requires careful patient assessment and targeted selection of proper fluid types, administration routes, and rates, along with adjustments during therapy tailored specifically as per the individual patient's fluid requirement and therapeutic response. Personalized fluid prescriptions and vigilant patient monitoring help avoid patient morbidity from body fluid deficiencies, fluid excess, and electrolyte derangements and support better patient outcomes. These guidelines provide an overview of fluid dynamics within the fluid spaces of the body, describe various types of fluids and their uses, and outline recommendations for fluid administration for resuscitation, rehydration, and maintenance purposes. The guidelines also outline approaches to fluid therapy for anesthetized patients and reiterate the recommendations of reduced fluid rates in this population of patients. Additionally, the guidelines include practical fluid therapy strategies for patients with various common disorders. The goal of these guidelines is to help veterinary professionals safely and effectively prescribe and administer fluid therapy for canine and feline patients.

Hyponatremia as a predictor of cognitive deterioration in hospitalized post-stroke patients

PURPOSE

Evidence is scarce regarding the association between hyponatremia and alterations in cognitive function among hospitalized older patients. We aimed to investigate the associations between hyponatremia and the baseline cognitive status, as well as the improvement in cognitive function, in hospitalized post-stroke patients.

METHODS

This retrospective cohort study included consecutive hospitalized post-stroke patients. Serum sodium concentrations were extracted from medical records based on blood tests performed within 24 h of admission, with hyponatremia defined as a serum sodium concentration < 135 mEq/L. The main outcomes included admission and discharge scores for cognitive levels, assessed through the cognitive domain of the Functional Independence Measure (FIM-cognition), as well as the score changes observed during the hospitalization period. Multivariate linear regression analyses were used to determine the association between hyponatremia and outcomes of interest, adjusted for potential confounders.

RESULTS

Data from 955 patients (mean age 73.2 years; 53.6 % men) were included in the analysis. The median baseline blood sodium level was 139 [137, 141], and 84 patients (8.8 %) exhibited hyponatremia. After full adjustment for confounders, the baseline hyponatremia was significantly and negatively associated with FIM-cognition values at admission (β = -0.009, p = 0.016), discharge (β = -0.038, p = 0.043), and the gain during hospital stay (β = -0.040, p = 0.011).

CONCLUSION

Baseline hyponatremia has demonstrated a correlation with decline in cognitive level over the course of rehabilitation in individuals after stroke. Assessing hyponatremia at the outset proves to be a pivotal prognostic indicator.

Associations between Baseline Hyponatremia and Activities of Daily Living and Muscle Health in Convalescent Stroke Patients

Objectives

Evidence is scarce regarding the association between hyponatremia and functional outcomes among older hospitalized patients. We aimed to evaluate the associations between baseline hyponatremia and improvement in activities of daily living (ADL) and muscle health in hospitalized post-stroke patients.

Methods

This retrospective cohort study included hospitalized post-stroke patients. Serum sodium concentrations were extracted from medical records based on blood tests performed within 24 h of admission, with hyponatremia defined as a serum sodium concentration below135 mEq/L. Primary outcome was the discharge ADL as assessed by the motor domain of the Functional Independence Measure (FIM-motor) and its corresponding gain during hospitalization. Other outcomes encompassed the discharge scores for skeletal muscle mass (SMI) and handgrip strength (HGS). Multivariate linear regression analyses were used to determine the association between hyponatremia and outcomes of interest, adjusted for potential confounders.

Results

Data from 955 patients (mean age 73.2 years; 53.6% men) were analyzed. The median baseline blood sodium level was 139 [interquartile range: 137, 141] mEq/L, and 84 patients (8.8%) exhibited hyponatremia. After full adjustment for confounders, baseline hyponatremia was significantly and negatively associated with FIM-motor at discharge (β=-0.036, P=0.033) and its gain during hospital stay (β=-0.051, P=0.033). Baseline hyponatremia exhibited an independent and negative association with discharge HGS (β=-0.031, P=0.027), whereas no significant association was found between baseline hyponatremia and discharge SMI (β=-0.015, P=0.244).

Conclusions

Baseline hyponatremia demonstrated a correlation with compromised ADL and muscle health in individuals undergoing rehabilitation after stroke.

Hyponatremia in Guillain-Barre Syndrome: A Review of Its Pathophysiology and Management

Guillain-Barre syndrome (GBS) is the commonest cause of acute polyradiculoneuropathy that requires hospitalization. Many of these patients experience systemic and disease-related complications during its course. Notable among them is hyponatremia. Though recognized for decades, the precise incidence, prevalence, and mechanism of hyponatremia in GBS are not well known. Hyponatremia in GBS patients is associated with more severe in-hospital disease course, prolonged hospitalization, higher mortality, increased costs, and a greater number of other complications in the hospital and worse functional status at 6 months and at 1 year. Though there are several reports of low sodium associated with GBS, many have not included the exact temporal relationship of sodium or its serial values during GBS thereby underestimating the exact incidence, prevalence, and magnitude of the problem. Early detection, close monitoring, and better understanding of the pathophysiology of hyponatremia have therapeutic implications. We review the complexities of the relationship between hyponatremia and GBS with regard to its pathophysiology and treatment.

Predictive value of hyponatremia for short-term mortality in supratentorial spontaneous intracerebral hemorrhage: a single center study

Background

Hyponatremia is a common electrolyte disturbance in patients with neurological disease; however, its predictive role for outcome in patients with supratentorial spontaneous intracerebral hemorrhage (sICH) is controversial. This study aims to explore the association between hyponatremia within 7 days after bleeding and 90-day mortality in patients with supratentorial sICH.

Methods

A retrospective analysis was conducted at our institution. Patients with sICH meeting the inclusion criteria were enrolled in this study. Multivariate regression analyses were performed to determine the predictive value of hyponatremia (serum sodium <135 mmol/L) for 90-day mortality and functional outcome. Subgroup analysis was performed based on the degree and duration of hyponatremia and therapeutic strategies. The Spearman correlation test was performed to explore the relationship between hyponatremia severity and duration with variables in a multivariate regression model. Kaplan-Meier curve was depicted to reveal the relationship between hyponatremia and mortality. The receiver operating characteristic (ROC) curve was plotted to show the diagnostic effect of the minimum concentration of serum sodium (sodiummin) on 90-day mortality.

Results

A total of 960 patients were enrolled, 19.6% (188) of whom were patients with hyponatremia and 26.0% (250) had 90-day mortality. The incidence of hyponatremia was roughly 2.5 times in non-survivors compared with survivors (34.8% vs. 14.2%). Multivariate regression analysis revealed that hyponatremia was the independent predictor of 90-day mortality (OR 2.763, 95%CI 1.836-4.157) and adverse outcome (OR 3.579, 95%CI 2.332-6.780). Subgroup analysis indicated an increased trend in mortality risk with both duration (more or less than 48 h) and severity of hyponatremia (mild, moderate, and severe) and confirmed the predictive value of hyponatremia for mortality in patients undergoing surgical intervention (external ventricular drainage, craniotomy, and decompressive craniectomy; all p < 0.05). The Spearman correlation test indicated no moderate or strong relationship between hyponatremia severity and duration with other variables in the multivariate model (all |rs| < 0.4). The ROC curve suggested the moderate diagnostic performance of sodiummin for mortality in both general patients and subgroups of therapeutic method patients (AUC from 0.6475 to 0.7384).

Conclusion

Hyponatremia occurring in the first 7 days after bleeding is an independent predictor of 90-day morality and adverse outcome. Rigorous electrolyte scrutiny in patients treated surgically is required.

Disorders of Sodium

Sodium imbalances are a common occurrence in the emergency department. Although recognition and diagnosis are relatively straightforward, discovering the cause and management should be approached systematically. The most important history items to ascertain is if the patient has symptoms and how long this imbalance has taken to develop. Treatment rapidity depends on severity of symptoms with the most rapid treatment occurring in only the severely symptomatic. Overcorrection has dire consequences and must be approached in a careful and systematic fashion in order to prevent these devastating consequences.

The Role of Ultrasonographic Inferior Vena Cava Measurement in the Volume-Based Classification of Patients With Hyponatremia

OBJECTIVES

To demonstrate the role of inferior vena cava (IVC) collapsibility in the assessment of volume status in hyponatremic critically ill patients in the emergency department (ED) with bedside IVC imaging and to predict volume status with response to fluid therapy.

METHODS

A prospective 110 hypotonic hyponatremic patients aged >18 years with a serum sodium level under 125 mEq/L and at least one symptom of hyponatremia, who presented or referred to the ED was conducted. Demographical, clinical, and laboratory characteristics with bedside measurement of IVC diameter of patients were recorded. Volume status was divided into 3 subgroups: hypovolemic-G1, euvolemic-G2, and hypervolemic-G3. An ED trainee with a certification to perform basic and advanced ultrasonography (USG) training carried out the USG examinations. A diagnostic algorithm approach was made according to the results.

RESULTS

Symptom severity was significantly greater in the hypervolemic group than the other groups (P = .009 and P = .034, respectively). Systolic blood pressure (SBP) and mean arterial pressure (MAP) were significantly lower in the hypovolemic group compared with the other groups (P < .001 and P = .003, respectively). There was a significant difference between the ultrasonographically measured IVC min, IVC max, and mean IVC values across the three volume-based groups (P < .001).

CONCLUSION

Considering the diversity of physical examination (PE) findings, with the highly heterogenous nature of hyponatremia, a new measurable algorithm can be developed on the basis of contemporary hyponatremic patient management guidelines.

Syndrome of Inappropriate Antidiuresis: From Pathophysiology to Management

Hyponatremia is the most common electrolyte disorder, affecting more than 15% of patients in the hospital. Syndrome of inappropriate antidiuresis (SIAD) is the most frequent cause of hypotonic hyponatremia, mediated by nonosmotic release of arginine vasopressin (AVP, previously known as antidiuretic hormone), which acts on the renal V2 receptors to promote water retention. There are a variety of underlying causes of SIAD, including malignancy, pulmonary pathology, and central nervous system pathology. In clinical practice, the etiology of hyponatremia is frequently multifactorial and the management approach may need to evolve during treatment of a single episode. It is therefore important to regularly reassess clinical status and biochemistry, while remaining alert to potential underlying etiological factors that may become more apparent during the course of treatment. In the absence of severe symptoms requiring urgent intervention, fluid restriction (FR) is widely endorsed as the first-line treatment for SIAD in current guidelines, but there is considerable controversy regarding second-line therapy in instances where FR is unsuccessful, which occurs in around half of cases. We review the epidemiology, pathophysiology, and differential diagnosis of SIAD, and summarize recent evidence for therapeutic options beyond FR, with a focus on tolvaptan, urea, and sodium-glucose cotransporter 2 inhibitors.

Hyponatremia and Outcome: Is Severity More Important Than Etiology?

BACKGROUND AND OBJECTIVE

Hyponatremia is the most common electrolyte abnormality encountered in a hospital setting, and the data regarding the contribution of hyponatremia to overall mortality are conflicting. The study objective was to determine patients' clinical profiles and outcomes with hyponatremia.

METHODS

 This prospective cross-sectional study was conducted at Dayanand Medical College and Hospital, Ludhiana, and included 375 adult patients aged more than 18 years with a confirmed diagnosis of hyponatremia. Patients were subdivided into three groups based on the severity of hyponatremia: mild (130-135 mmol/L), moderate (125-129 mmol/L), and profound (<125 mmol/L).

RESULTS

The most common symptom was confusion (57.3%) followed by deep somnolence (40%) and nausea (36.8%). The most common cause of hyponatremia was diuretics (30.7%), followed by the syndrome of inappropriate antidiuretic hormone secretion (SIADH) (17.8%) and chronic liver disease (CLD) (14.1%). The severity of hyponatremia did not significantly influence the outcome. Patients with CLD and chronic kidney disease (CKD) as the etiology of hyponatremia had significantly worse outcomes compared to other causes of hyponatremia. The most common type was hypovolemic hypotonic followed by euvolemic hypotonic and hypervolemia hypotonic hyponatremia. Nearly half of the total deaths were observed in the hypervolemic hyponatremia group and were significantly higher compared to the other two groups (p=0.001). Correction of hyponatremia (i.e., serum sodium >135 mmol/L) was significantly linked with good outcomes (p=0.003).

CONCLUSION

Our study showed that the etiology of hyponatremia was a more important prognostic indicator rather than the severity of hyponatremia. Normalization of serum sodium was associated with improved survival.

Hyponatremia and its associated factors in children admitted to the pediatric intensive care unit in eastern Ethiopia: a cross-sectional study

BACKGROUND

Hyponatremia is a serious problem that leads to substantial increases morbidity and mortality in critically ill children. The identification of risk factors, implementation of preventive measures, and timely diagnosis and management are crucial to reduce adverse events related to hyponatremia. Despite the higher burden of the problem in Ethiopia, evidence related to the risk factors for hyponatremia among children in Ethiopia is limited; in particular, no study has been identified in eastern Ethiopia. Therefore, we aimed to determine the magnitude of hyponatremia and its associated factors in children admitted to the pediatric intensive care unit at the Hiwot Fana Comprehensive Specialized University Hospital.

METHODS

A facility-based cross-sectional study was conducted using 422 medical records of pediatric patients admitted to the pediatric intensive care unit at Hiwot Fana Comprehensive Specialized University Hospital from January 2019 to December 2022. Medical records were reviewed to collect data. Data were analyzed using a statistical package for social sciences (SPSS) version 26. A binary logistic regression model with an adjusted odds ratio (aOR) and a 95% confidence interval (CI) was used to identify factors associated with the outcome variable. Statistical significance was set at p < 0.05.

RESULTS

The magnitude of hyponatremia was 39.1% (95% CL: 34.4-43.8%). The age of the child (aOR = 2.37;95% CL:1.31-4.31), diagnosis of sepsis (aOR = 2.33; 95% CL:1.41-3.84),   surgical procedures (aOR = 2.39; 95% CL:1.26-4.56), nutritional status (aOR = 2.60; 95% CL:1.51-4.49), and length of hospital stay (aOR = 3.04; 95% CL: 1.73-5.33) were factors significantly associated with hyponatremia.

CONCLUSIONS

Four out of ten children admitted to pediatric intensive care units had hyponatremia. Hyponatremia was significantly associated with the age of the child, malnutrition, sepsis, surgical procedures, and length of hospital stay. To reduce the burden of hyponatremia and associated mortality, attention should be focused on improving the care of malnourished children, and those with sepsis, and the quality of postoperative monitoring services. Moreover, intervention strategies aimed at reducing the burden of hyponatremia should target the identified factors.

Euvolaemic hyponatraemia as a rare first presentation of chronic hypopituitarism

A man in his late 40s with no significant medical history presented with 2 weeks of lethargy, nausea and dizziness, alongside worsening headaches. Initial assessment revealed severe hyponatraemia and secondary hypothyroidism; urgent MRI pituitary was requested with a clinical suspicion of pituitary apoplexy. This demonstrated a likely cystic pituitary adenoma, with further testing revealing pituitary gland suppression, leading to a diagnosis of chronic secondary hypopituitarism. Initiating hormone replacement allowed substantial reported improvements in this patient's quality of life.A review of the patient's work-up revealed areas in which best practice was not followed. Cortisol measurements and paired urinary and serum osmolalities were initially not sent, nor results appropriately chased. A subsequent literature review identified that conformation with national and local guidelines on hyponatraemia management is poor. This patient's case, when combined with the literature review, provides evidence to support methods to increase educational awareness of an appropriate work-up of hyponatraemia among clinicians.

Initiatives to Reduce the Content of Sodium in Food Products and Meals and Improve the Population's Health

Table salt is the main source of sodium (Na) in the human diet. Excessive supply of Na in a diet is strongly linked to many non-communicable human diseases, such as hypertension, obesity and stomach cancer. The World Health Organization recommends that daily intake of salt in adult diets should be kept below 5 g/person/day, which corresponds to 2 g Na/person/day. However, on average, adults consume about 9-10 g/person/day, and children and young people about 7-8 g/person/day. Initiatives to reduce salt intake include modifications of food composition in collaboration with the food industry, education of consumers, salt marking on foodstuff labels and taxation of salt. A need also exists to educate society so that they choose low-sodium products. In view of the food technology and amount of salt intake, the most important and the easiest change to make is to reduce the content of salt in baked goods. This paper analyses the results of surveys regarding strategies to reduce salt content in food products and considers multifaceted initiatives to reduce salt intake as a possible efficient method of improving the population's health status.

Clinical Approach to Euvolemic Hyponatremia

Euvolemic hyponatremia is frequently encountered in hospitalized patients and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause in most patients. SIADH diagnosis is confirmed by decreased serum osmolality, inappropriately elevated urine osmolality (>100 mosmol/L), and elevated urine sodium (Na) levels. Patients should be screened for thiazide use and adrenal or thyroid dysfunction should be ruled out before making a diagnosis of SIADH. Clinical mimics of SIADH like cerebral salt wasting and reset osmostat should be considered in some patients. The distinction between acute (<48 hours) versus chronic (>48 hours or without baseline labs) hyponatremia and clinical symptomatology are important to initiate proper therapy. Acute hyponatremia is a medical emergency and osmotic demyelination syndrome (ODS) occurs commonly when rapidly correcting any chronic hyponatremia. Hypertonic (3%) saline should be used in patients with significant neurologic symptoms and maximal correction of serum Na level should be limited to <8 mEq over 24 hours to prevent the ODS. Simultaneous administration of parenteral desmopressin is one of the best ways to prevent overly rapid Na correction in high-risk patients. Free water restriction combined with increased solute intake (e.g., urea) is the most effective therapy to treat patients with SIADH. 0.9% saline acts as a hypertonic solution in patients with hyponatremia and should be avoided in the treatment of SIADH due to rapid fluctuations in serum Na levels. Dual effects of 0.9% saline resulting in rapid correction of serum Na during infusion (inducing ODS) and post-infusion worsening of serum Na levels are described in the article with clinical examples.

Exercise-Associated Hyponatremia in Marathon Runners

Exercise-associated hyponatremia (EAH) was first described as water intoxication by Noakes et al. in 1985 and has become an important topic linked to several pathological conditions. However, despite progressive research, neurological disorders and even deaths due to hyponatremic encephalopathy continue to occur. Therefore, and due to the growing popularity of exercise-associated hyponatremia, this topic is of great importance for marathon runners and all professionals involved in runners' training (e.g., coaches, medical staff, nutritionists, and trainers). The present narrative review sought to evaluate the prevalence of EAH among marathon runners and to identify associated etiological and risk factors. Furthermore, the aim was to derive preventive and therapeutic action plans for marathon runners based on current evidence. The search was conducted on PubMed, Scopus and Google Scholar using a predefined search algorithm by aggregating multiple terms (marathon run; exercise; sport; EAH; electrolyte disorder; fluid balance; dehydration; sodium concentration; hyponatremia). By this criterion, 135 articles were considered for the present study. Our results revealed that a complex interaction of different factors could cause EAH, which can be differentiated into event-related (high temperatures) and person-related (female sex) risk factors. There is variation in the reported prevalence of EAH, and two major studies indicated an incidence ranging from 7 to 15% for symptomatic and asymptomatic EAH. Athletes and coaches must be aware of EAH and its related problems and take appropriate measures for both training and competition. Coaches need to educate their athletes about the early symptoms of EAH to intervene at the earliest possible stage. In addition, individual hydration strategies need to be developed for the daily training routine, ideally in regard to sweat rate and salt losses via sweat. Future studies need to investigate the correlation between the risk factors of EAH and specific subgroups of marathon runners.

A Medical Conundrum in a Surgical Setting: Lessons Learned From an Atypical Case of Hyponatremia

In the world of medicine and specifically endocrinology, hyponatremia is one of the commonest electrolyte abnormalities that result in a varied spectrum of presentations. Patients can incur symptoms ranging from lethargy, light-headedness, and confusion to much more severe symptoms such as vomiting, abdominal pain, deterioration in consciousness, and, in critical cases, even seizures. In elderly patients, hyponatremia is a major cause of Delirium and if not treated appropriately, can result in adverse outcomes and complications. In severe cases of hyponatremia, the opinion of an endocrinologist must be sought early for a conscientious investigation of the underlying etiology, as this prevents the need for unnecessary interventions, and thus reduces the risk of potential harm. Despite being a common electrolyte abnormality, hyponatremia can be associated with rare and uncommon etiologies, one of them being acute intermittent porphyria (AIP) as seen in our case. Due to the non-specific presentation of AIP, medical and healthcare professionals must be cautious of this condition, since it can mimic an acute abdomen. Symptoms of AIP usually overlap with other conditions, thus resulting in a diagnostic dilemma. Triggers and factors leading to acute attacks of AIP must be explored and rationalized appropriately, involving a thorough review of a patient's medication and social history. Moreover, discussion in a multidisciplinary team (MDT) setting for such complex presentations has a positive impact on patient care and is therefore recommended.

Life-Threatening Hyponatremia Secondary to Chronic Kratom Use: A Case Presentation

Hyponatremia is defined as a serum sodium concentration of less than 135 mEq/L. Severe hyponatremia is defined as a serum sodium concentration of less than 125 mEq/L and is a life-threatening complication that must be managed promptly to avoid irreversible neurological damage. One particular cause of hyponatremia is the ingestion of recreational drugs, such as 3,4-Methylenedioxymethamphetamine (MDMA), also known as Ecstasy. Another drug with limited understanding of its adverse effects on specific individuals and is widely available to purchase legally is Kratom (Mitragyna speciosa). Here, we present the case of severe hyponatremia secondary to the ingestion of Kratom. Kratom is believed to act on various pain-modulating receptors and may explain its role in causing hyponatremia. Unfortunately, Kratom remains poorly understood and underreported. Our case illustrates the need for further in-depth studies to determine the complete toxic profile of Kratom, providing awareness to clinicians in anticipation of severe complications that may develop.

Demystifying hyponatremia: A clinical guide to evaluation and management

Hyponatremia (serum sodium <135 mEq/L) is a frequent electrolyte abnormality complicating the clinical care of hospitalized patients. Hyponatremia has been associated with an increased risk of mortality. Hyponatremia can be seen in patients with euvolemia, hypovolemia, or hypervolemia. Evaluation of hyponatremia relies on clinical assessment and estimation of serum sodium, urine electrolytes, and serum and urine osmolality in addition to other case-specific laboratory parameters. In addition, point-of-care ultrasonography is an important adjunct to physical assessment in estimation of volume status. Understanding the pathophysiology of the underlying process can lead to a timely diagnosis and appropriate management of hyponatremia.

Replacing salt with low-sodium salt substitutes (LSSS) for cardiovascular health in adults, children and pregnant women

BACKGROUND

Elevated blood pressure, or hypertension, is the leading cause of preventable deaths globally. Diets high in sodium (predominantly sodium chloride) and low in potassium contribute to elevated blood pressure. The WHO recommends decreasing mean population sodium intake through effective and safe strategies to reduce hypertension and its associated disease burden. Incorporating low-sodium salt substitutes (LSSS) into population strategies has increasingly been recognised as a possible sodium reduction strategy, particularly in populations where a substantial proportion of overall sodium intake comes from discretionary salt. The LSSS contain lower concentrations of sodium through its displacement with potassium predominantly, or other minerals. Potassium-containing LSSS can potentially simultaneously decrease sodium intake and increase potassium intake.  Benefits of LSSS include their potential blood pressure-lowering effect and relatively low cost. However, there are concerns about potential adverse effects of LSSS, such as hyperkalaemia, particularly in people at risk, for example, those with chronic kidney disease (CKD) or taking medications that impair potassium excretion.

OBJECTIVES

To assess the effects and safety of replacing salt with LSSS to reduce sodium intake on cardiovascular health in adults, pregnant women and children.

SEARCH METHODS

We searched MEDLINE (PubMed), Embase (Ovid), Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science Core Collection (Clarivate Analytics), Cumulative Index to Nursing and Allied Health Literature (CINAHL, EBSCOhost), ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) up to 18 August 2021, and screened reference lists of included trials and relevant systematic reviews. No language or publication restrictions were applied.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and prospective analytical cohort studies in participants of any age in the general population, from any setting in any country. This included participants with non-communicable diseases and those taking medications that impair potassium excretion. Studies had to compare any type and method of implementation of LSSS with the use of regular salt, or no active intervention, at an individual, household or community level, for any duration.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles, abstracts and full-text articles to determine eligibility; and extracted data, assessed risk of bias (RoB) using the Cochrane RoB tool, and assessed the certainty of the evidence using GRADE. We stratified analyses by adults, children (≤ 18 years) and pregnant women. Primary effectiveness outcomes were change in diastolic and systolic blood pressure (DBP and SBP), hypertension and blood pressure control; cardiovascular events and cardiovascular mortality were additionally assessed as primary effectiveness outcomes in adults. Primary safety outcomes were change in blood potassium, hyperkalaemia and hypokalaemia.

MAIN RESULTS

We included 26 RCTs, 16 randomising individual participants and 10 randomising clusters (families, households or villages). A total of 34,961 adult participants and 92 children were randomised to either LSSS or regular salt, with the smallest trial including 10 and the largest including 20,995 participants. No studies in pregnant women were identified. Studies included only participants with hypertension (11/26), normal blood pressure (1/26), pre-hypertension (1/26), or participants with and without hypertension (11/26). This was unknown in the remaining studies. The largest study included only participants with an elevated risk of stroke at baseline. Seven studies included adult participants possibly at risk of hyperkalaemia. All 26 trials specifically excluded participants in whom an increased potassium intake is known to be potentially harmful. The majority of trials were conducted in rural or suburban settings, with more than half (14/26) conducted in low- and middle-income countries. The proportion of sodium chloride replacement in the LSSS interventions varied from approximately 3% to 77%. The majority of trials (23/26) investigated LSSS where potassium-containing salts were used to substitute sodium. In most trials, LSSS implementation was discretionary (22/26). Trial duration ranged from two months to nearly five years.  We assessed the overall risk of bias as high in six trials and unclear in 12 trials. LSSS compared to regular salt in adults: LSSS compared to regular salt probably reduce DBP on average (mean difference (MD) -2.43 mmHg, 95% confidence interval (CI) -3.50 to -1.36; 20,830 participants, 19 RCTs, moderate-certainty evidence) and SBP (MD -4.76 mmHg, 95% CI -6.01 to -3.50; 21,414 participants, 20 RCTs, moderate-certainty evidence) slightly.  On average, LSSS probably reduce non-fatal stroke (absolute effect (AE) 20 fewer/100,000 person-years, 95% CI -40 to 2; 21,250 participants, 3 RCTs, moderate-certainty evidence), non-fatal acute coronary syndrome (AE 150 fewer/100,000 person-years, 95% CI -250 to -30; 20,995 participants, 1 RCT, moderate-certainty evidence) and cardiovascular mortality (AE 180 fewer/100,000 person-years, 95% CI -310 to 0; 23,200 participants, 3 RCTs, moderate-certainty evidence) slightly, and probably increase blood potassium slightly (MD 0.12 mmol/L, 95% CI 0.07 to 0.18; 784 participants, 6 RCTs, moderate-certainty evidence), compared to regular salt.  LSSS may result in little to no difference, on average, in hypertension (AE 17 fewer/1000, 95% CI -58 to 17; 2566 participants, 1 RCT, low-certainty evidence) and hyperkalaemia (AE 4 more/100,000, 95% CI -47 to 121; 22,849 participants, 5 RCTs, moderate-certainty evidence) compared to regular salt. The evidence is very uncertain about the effects of LSSS on blood pressure control, various cardiovascular events, stroke mortality, hypokalaemia, and other adverse events (very-low certainty evidence). LSSS compared to regular salt in children: The evidence is very uncertain about the effects of LSSS on DBP and SBP in children. We found no evidence about the effects of LSSS on hypertension, blood pressure control, blood potassium, hyperkalaemia and hypokalaemia in children.

AUTHORS' CONCLUSIONS

When compared to regular salt, LSSS probably reduce blood pressure, non-fatal cardiovascular events and cardiovascular mortality slightly in adults. However, LSSS also probably increase blood potassium slightly in adults. These small effects may be important when LSSS interventions are implemented at the population level. Evidence is limited for adults without elevated blood pressure, and there is a lack of evidence in pregnant women and people in whom an increased potassium intake is known to be potentially harmful, limiting conclusions on the safety of LSSS in the general population. We also cannot draw firm conclusions about effects of non-discretionary LSSS implementations. The evidence is very uncertain about the effects of LSSS on blood pressure in children.

Cryptococcal Meningitis in Kidney Transplant Recipients: A Two-Decade Cohort Study in France

Cryptococcosis is the third most common cause of invasive fungal infection in solid organ transplant recipients and cryptococcal meningitis (CM) its main clinical presentation. CM outcomes, as well as its clinical features and radiological characteristics, have not yet been considered on a large scale in the context of kidney transplantation (KT). We performed a nationwide retrospective study of adult patients diagnosed with cryptococcosis after KT between 2002 and 2020 across 30 clinical centers in France. We sought to describe overall and graft survival based on whether KT patients with cryptococcosis developed CM or not. Clinical indicators of CNS involvement and brain radiological characteristics were assessed. Eighty-eight cases of cryptococcosis were diagnosed during the study period, with 61 (69.3%) cases of CM. Mortality was high (32.8%) at 12 months (M12) but not significantly different whether or not patients presented with CM. Baseline hyponatremia and at least one neurological symptom were independently associated with CM (p < 0.001). Positive serum cryptococcal antigen at diagnosis was also significantly associated with CM (p < 0.001). On magnetic resonance imaging (MRI), three patterns of brain injury were identified: parenchymal, meningeal, and vascular lesions. Although CM does not affect graft function directly, it entails a grim prognosis.

Hyponatremia management among patients admitted to tertiary hospital: A retrospective evaluation

Objective:

The aim of this study is to compare the adherence to the guidelines in patients presenting with hyponatremia defined as a sodium (Na) level ⩽120 mEq/L, treated with 3% hypertonic saline or normal saline. The comparison included 3% hypertonic saline use, safe serum sodium increases within 24 and 48 h, frequency of hyponatremia-related complications, and length of stay.

Methods:

This retrospective observational study enrolled 122 patients with serum sodium ⩽120 mEq/L admitted to the Internal Medicine Department, King Abdulaziz Medical City, National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia, from January 2016 to December 2017. The patients were treated with either 3% hypertonic saline or normal saline.

Results:

Of the 122 patients, 105 (83.3%) received normal saline, and 17 (13.5%) received hypertonic saline. In the normal saline group, the mean serum sodium increase at 24 h was lower (6.60 ± 4.75) compared to the hypertonic saline group (9.24 ± 5.04). The length of stay was longer in the normal saline group (10.35 ± 13.90) compared to the hypertonic saline group (4.35 ± 3.39). A small proportion (8.7%) of the normal saline group had a serum sodium increase >12 mg/dL at 24 h compared to 29.4% for the hypertonic saline group, and the difference was statistically significant (p value = 0.013). Almost one-third of the sample (36%) presented with complications, the majority (77.3%, n = 34) had a serum sodium of ⩽115 mg/dL, and 22.7% (n = 10) with a serum sodium of 116–120 mg/dL (p value = 0.041).

Conclusion:

Despite the strong recommendation for 3% hypertonic saline use in severe hyponatremia, many practitioners still use normal saline, even in patients with serum sodium ⩽120 mEq/L. Normal saline showed some efficacy in managing hyponatremia in asymptomatic cases; however, severe cases may have a delayed correction, hyponatremia-related complications, and an extended length of stay.

Acute Kidney Injury and Hyponatremia in Ultra-Trail Racing: A Systematic Review

Background and objectives: Ultra-trail races can cause episodes of acute kidney injury (AKI) and exercise-associated hyponatremia (EAH) in healthy subjects without previous renal pathology. This systematic review aims to review the incidence of these two syndromes together and separately taking into account the length and elevation of the ultra-trail race examined. Materials and Methods: A systematic review was conducted through electronic search in four electronic databases (PubMed, EBSCO, Web of Science and Alcorze). Results: A total of 1127 articles published between January 2006 and December 31, 2021 were included, 28 of which met the inclusion criteria. The studies were categorized according to the length and stages of the race in four categories: medium (42 to 69 km), long (70 to 99 km), extra (>100 km) and multi-stage if they included various stages. A total of 2950 runners (666 females and 2284 males) were extracted from 28 publications. The AKI incidence found was 42.04% (468 cases of 1113), and 195 of 2065 were diagnosed with EAH, accounting for 9.11%. The concurrence of both pathologies together reached 11.84% (27 individuals) from a total of 228 runners with AKI and EAH simultaneously analyzed. Sorted by race category, the AKI+EAH cases were distributed as follows: 18 of 27 in the extra (13.63% and n = 132), 4 in the large (5.79% and n = 69) and 5 in the medium category (18.15% and n = 27). Conclusions: According to these results, extra and medium races showed a similar incidence of AKI+EAH. These findings underline the importance of the duration and intensity of the race and may make them responsible for the etiology of these medical conditions. Due to their variable incidence, EAH and AKI are often underdiagnosed, leading to poorer prognosis, increased condition seriousness and hindered treatment. The results of this review urge participants, coaches and race organizers to take measures to improve the early diagnosis and urgent treatment of possible EAH and AKI cases.

Kidney Transplant Recipient with Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) secondary to COVID-19 pneumonia: A Case Report

Background

Currently, COVID-19 is becoming one of the most common causes of viral pneumonia worldwide. In the medical literature, very few case reports describe the association between COVID-19 and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) in kidney transplant patients.

Methods

A 74-year-old immunocompromised man post–kidney transplant presented with nonspecific symptoms consisting of fatigue, malaise, and anorexia. He was also found to have hyponatremia in the context of pulmonary insults. SIADH in the setting of COVID-19 pneumonia was diagnosed after exclusion of other causes of hyponatremia. He was treated for COVID-19 pneumonia with antiviral therapy, secondary bacterial infection prophylaxis, dexamethasone and ventilatory support in addition to modification of antirejection medications.

Results

The patient has improved and his serum sodium normalized with management of primary insult.

Conclusions. SIADH should be suspected in transplant patients with COVID-19 pneumonia once they develops hyponatremia. The decision of intravenous fluid administration should be taken carefully in these settings.

The History of Intravenous and Oral Rehydration and Maintenance Therapy of Cholera and Non-Cholera Dehydrating Diarrheas: A Deconstruction of Translational Medicine: From Bench to Bedside?

The "bench to bedside" (BTB) paradigm of translational medicine (TM) assumes that medical progress emanates from basic science discoveries transforming clinical therapeutic models. However, a recent report found that most published medical research is false due, among other factors, to small samples, inherent bias and inappropriate statistical applications. Translation-blocking factors include the validity (or lack thereof) of the underlying pathophysiological constructs and related therapeutic paradigms and adherence to faulty traditional beliefs. Empirical discoveries have also led to major therapeutic advances, but scientific dogma has retrospectively retranslated these into the BTB paradigm. A review of the history of intravenous (I.V.) and oral therapy for cholera and NDDs illustrates some fallacies of the BTB model and highlights pitfalls blocking translational and transformative progress, and retro-translational factors, including programmatic modifications of therapeutic advances contradicting therapeutic paradigms and medical economic factors promoting more expensive and profitable medical applications inaccessible to resource-limited environments.

Acute Severe Hypovolemic Hyponatremia in a Patient on Intravenous Dexamethasone

Hyponatremia is a commonly encountered electrolyte imbalance with varied etiology. Hyponatremia can be broadly classified as hypotonic, isotonic, and hypertonic hyponatremia based on the tonicity of plasma. Hypotonic hypovolemia is further classified as hypovolemic, euvolemic, and hypervolemic hyponatremia based on the volume status. Gastrointestinal fluid and electrolyte losses, secondary to vomiting and diarrhea, is an important predisposition to hypotonic hypovolemic hyponatremia. The renin-angiotensin-aldosterone system (RAAS) and antidiuretic hormone (ADH) play a pivotal role in maintaining intravascular volume and serum sodium concentration. Dexamethasone is a potent glucocorticoid with minimal mineralocorticoid activity. It negatively affects the hypothalamic-pituitary-adrenal axis and the renin-angiotensin-aldosterone system, particularly with prolonged administration. In the index case, acute severe hypovolemic hyponatremia ensued on the third post-procedure (endovascular embolization of traumatic carotico-cavernous fistula (CCF)) day while the patient was on intravenous dexamethasone. This case underscores that even small fluid and electrolyte imbalance in the setting of dexamethasone therapy may lead to severe hypovolemic hyponatremia, which requires specific therapy.

Hydrocephalus-Associated Hyponatremia: A Review

Hydrocephalus is the pathological accumulation of cerebrospinal fluid within the ventricles of the brain. Hydrocephalus may be broadly divided into three categories: congenital, acquired, or other. Hyponatremia, serum sodium level <135 meq/ml, may be caused by dilution (e.g. syndrome of inappropriate antidiuretic hormone (SIADH)), depletion (e.g. cerebral salt wasting (CSW)), or delusion (e.g. psychogenic water intake) etiologies. This review discusses “hydrocephalus-associated hyponatremia” as a clinical entity, distinct from SIADH and CSW.

Some experts believe that in hydrocephalus patients, increased pressure on the hypothalamus leads to the release of antidiuretic hormone (ADH), which in turn causes hyponatremia. The true etiology of hyponatremia is critical to diagnose, as it will determine the treatment. So while both SIADH and CSW may result in hyponatremia, the former is treated with fluid restriction, while the latter requires fluid repletion; treating SIADH as CSW, and vice versa, will exacerbate the hyponatremia.

The etiology and severity of hyponatremia will determine the management. For hydrocephalus-associated hyponatremia, treating the underlying problem (i.e. hydrocephalus) is the mainstay of therapy. Theoretically, treatment of hydrocephalus-related hyponatremia with CSF-diversion procedures should relieve the pressure on the hypothalamus, mitigating ADH production, which in turn will decrease sodium excretion and ameliorate the hyponatremia.

Cerebral Salt-Wasting Syndrome in a Patient With Active Pulmonary Tuberculosis

A 37-year-old female with a medical history of recently diagnosed active pulmonary tuberculosis and a new intracranial lesion presented with altered mental status, nausea, and vomiting for two days. An initial physical examination revealed that the patient was euvolemic. Laboratory findings revealed a serum sodium concentration of 105 mEq/L. During her admission, she was initially managed with lactated ringer solution in the emergency department, followed by 3% normal saline in the intensive care unit, and, eventually, on oral sodium chloride and fluid restriction on discharge. Once she was stabilized, she had episodes of dizziness, and concerns were raised about the salt-wasting syndrome.

Clinical Implications, Evaluation, and Management of Hyponatremia in Cirrhosis

Hyponatremia is the most common electrolyte abnormality in patients with decompensated cirrhosis on Liver Transplantation (LT) waiting list. Most of these patients have dilutional or hypervolemic hyponatremia secondary to splanchnic vasodilatation. Excessive secretion of the antidiuretic hormone also plays an important role. Hypervolemic hyponatremia is commonly associated with refractory ascites, spontaneous bacterial peritonitis, and hepatic encephalopathy. Although uncommon, the use of diuretics and laxatives can cause hypovolemic hyponatremia that is characterized by the striking absence of ascites or pedal edema. Clinical features are often nonspecific and depend on the acuity of onset rather than the absolute value of serum sodium. Symptoms may be subtle, including nausea, lethargy, weakness, or anorexia. However, rarely patients may present with confusion, seizures, psychosis, or coma. Treatment includes discontinuation of diuretics, beta-blockers, and albumin infusion. Hypertonic saline (3%) infusion may be used in patients with very low serum sodium (<110 mmol/L) or when patients present with seizures or coma. Short-term use of Vasopressin (V₂) receptor antagonists may also be used to normalize sodium levels prior to LT. However, all these measures may be futile, and LT remains the definite treatment in these patients to improve survival. In this review, we describe the classification, pathogenesis of hyponatremia, and its clinical implications in patients with cirrhosis. Approach to these patients along with management will also be discussed briefly.

Hyponatremia in melioidosis: Analysis of 10-year data from a hospital-based registry

Introduction:

Methods:

Results:

Conclusion:

Using Tolvaptan to Treat Hyponatremia: Results from a Post-authorization Pharmacovigilance Study

Introduction

Hyponatremia is a common condition of varying etiology among hospitalized patients and is associated with adverse outcomes. Treatment to normalize serum sodium is advisable. Tolvaptan received European Union marketing authorization for hyponatremia secondary to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Post-marketing pharmacovigilance activities were required to characterize the safety profile of tolvaptan more fully in this population, which is often elderly with a high burden of comorbid illness.

Methods

This was a prospective, observational, multinational, post-authorization pharmacovigilance study (NCT01228682) in seven European countries. Hospitalized patients were enrolled who received tolvaptan for hyponatremia associated with SIADH and consented to data collection. Tolvaptan was initiated and assessments performed at physician discretion per local standards of care. To reflect actual clinical practice, no assessments or procedures were required outside the standard of care. Patients who continued to receive long-term tolvaptan following hospital discharge and provided consent received follow-up from their community physicians.

Results

A total of 252 patients (mean age 70.6 years) enrolled. Mean tolvaptan treatment duration was 139.4 days, median 18.5 (range 1–1130) days; most frequent dose was 15 mg/day (used in 75% of patients). Serum sodium increased from baseline (mean 123.2 mmol/l) during treatment week 1 and remained stable during follow-up, with little difference across doses of 7.5, 15, and 30 mg/day. Hyponatremia symptoms (e.g., confusion, unsteady gait, lethargy) were present in 122/252 (48.4%) patients at pre-treatment baseline, decreasing to 46/252 (18.3%) during treatment. Sixty-two patients (24.6%; mean baseline serum sodium 120 mmol/l) experienced rapid correction of hyponatremia within 72 h. No osmotic demyelination syndrome occurred.

Conclusion

In clinical practice, tolvaptan improved serum sodium and decreased hyponatremia symptoms in hyponatremia secondary to SIADH. Serum sodium should be monitored during treatment to minimize risk of rapid correction.

Trial Registration

Clinicaltrials.gov identifier NCT01228682.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01947-9.

Hospitalized patients often experience abnormally low blood sodium levels (hyponatremia), which can cause significant symptoms and poses a serious health risk (Wald et al. in Arch Intern Med 170:294–302, 2010). Yet, increasing sodium levels too rapidly in these patients can unintentionally cause osmotic demyelination syndrome, resulting in long-term neurologic damage or death. Tolvaptan was approved in the European Union to treat one type of hyponatremia caused by a hormonal imbalance known as the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Tolvaptan effectively increased patient sodium levels in clinical trials, but real-world data are needed to understand tolvaptan treatment more fully in everyday clinical practice. We evaluated patterns of use, efficacy, and safety of tolvaptan in patients treated in hospitals and after discharge for hyponatremia due to SIADH. Tolvaptan was correctly used to treat only hyponatremia caused by SIADH in nearly all of the 252 patients studied. Patient sodium levels increased in the first week of tolvaptan treatment and then stabilized. Hyponatremia symptoms, such as confusion, nausea, tiredness, and dizziness, were present in 48.4% of patients before treatment and in 18.3% after starting tolvaptan. Consistent with earlier studies, some patients (24.6%) experienced excessively rapid correction of hyponatremia. However, no subsequent neurologic problems or deaths were attributed to the rapid correction, which suggests that medical providers were carefully monitoring and managing sodium levels to prevent serious consequences. Our study indicates that tolvaptan is being used safely and effectively to treat hyponatremia due to SIADH in a patient population with complex medical needs.

Elderly with refractory chronic severe hyponatremia and anesthesia management dilemma: a case report with literature review

Hyponatremia is a common electrolyte disorder, especially in the frail elderly population. With the increasing number of surgeries in the aging population, hyponatremia is frequently encountered by anesthesiologists and surgeons. Unfortunately, management of hyponatremia is often complex in the elderly population as it is often multifactorial, and they are physiologically susceptible. While it is well known that preoperative hyponatremia is associated with increased perioperative morbidity and mortality, a lack of recommendations or guidelines adds to the dilemma in managing such cases. The most common cause of chronic hyponatremia in the elderly is the syndrome of inappropriate antidiuretic hormone (SIADH), which can be resistant to conventional treatment. On the other hand, paraneoplastic SIADH leading to hyponatremia is rare, and surgery may be the only option available for its correction. We present a case of a 78- years-gentleman to highlight such a dilemma. He was diagnosed with renal cell carcinoma and had chronic refractory severe hyponatremia despite treatment with fluid restriction, low dose hydrocortisone, tolvaptan, and 3% sodium chloride.

Frequency of Electrolyte Imbalance in Patients Presenting With Acute Stroke

Introduction Electrolyte disturbances are commonly reported in acute stroke in studies conducted in the western world. Presently, the data available about the prevalence of electrolyte disturbance in patients with stroke are not sufficient, especially from developing countries. The purpose of our study is to determine the frequency of occurrence of electrolyte imbalance in patients presenting with acute stroke in a tertiary care hospital. Methods This descriptive cross-sectional study was conducted in the department of internal medicine and neurology in a tertiary care hospital, Pakistan, from December 2019 to March 2021. A total of 300 patients, aged between 30 and 70 years, with either ischemic or hemorrhagic stroke, as diagnosed on contrast tomography (CT) scan of the head or magnetic resonance imaging (MRI) of the brain, were enrolled in the study. The biochemical analysis of the stroke patients was done. Results Out of the 300 participants, 139 (46.3%) participants were from the ischemic stroke group while 161 (53.7%) were from the hemorrhagic stroke group. The mean sodium level was significantly lower in the ischemic group as compared to the hemorrhagic group (129.41 ± 3.12 mEq/L vs. 134.42 ± 3.46 mEq/L; p-value: <0.0001). Potassium level was significantly higher in the hemorrhagic group compared to the ischemic group (6.27 ± 1.12 mmol vs. 4.31 ± 0.71 mmol; p-value: <0.0001). Conclusion Patients coming to emergency with stroke should be screened immediately for electrolyte imbalance. Early identification of rapid imbalances of serum electrolytes may aid in prompt medical intervention and resultant improved outcomes in stroke patients. It is crucial that electrolyte imbalances in these patients are closely monitored to avoid any complications.

Neuronal Swelling: A Non-osmotic Consequence of Spreading Depolarization

An acute reduction in plasma osmolality causes rapid uptake of water by astrocytes but not by neurons, whereas both cell types swell as a consequence of lost blood flow (ischemia). Either hypoosmolality or ischemia can displace the brain downwards, potentially causing death. However, these disorders are fundamentally different at the cellular level. Astrocytes osmotically swell or shrink because they express functional water channels (aquaporins), whereas neurons lack functional aquaporins and thus maintain their volume. Yet both neurons and astrocytes immediately swell when blood flow to the brain is compromised (cytotoxic edema) as following stroke onset, sudden cardiac arrest, or traumatic brain injury. In each situation, neuronal swelling is the direct result of spreading depolarization (SD) generated when the ATP-dependent sodium/potassium ATPase (the Na+/K+ pump) is compromised. The simple, and incorrect, textbook explanation for neuronal swelling is that increased Na+ influx passively draws Cl- into the cell, with water following by osmosis via some unknown conduit. We first review the strong evidence that mammalian neurons resist volume change during acute osmotic stress. We then contrast this with their dramatic swelling during ischemia. Counter-intuitively, recent research argues that ischemic swelling of neurons is non-osmotic, involving ion/water cotransporters as well as at least one known amino acid water pump. While incompletely understood, these mechanisms argue against the dogma that neuronal swelling involves water uptake driven by an osmotic gradient with aquaporins as the conduit. Promoting clinical recovery from neuronal cytotoxic edema evoked by spreading depolarizations requires a far better understanding of molecular water pumps and ion/water cotransporters that act to rebalance water shifts during brain ischemia.

Hypohydration produced by high-intensity intermittent running increases biomarkers of renal injury in males

Purpose

Whilst there is evidence to suggest that hypohydration caused by physical work in the heat increases renal injury, whether this is the case during exercise in temperate conditions remains unknown. This study investigated the effect of manipulating hydration status during high-intensity intermittent running on biomarkers of renal injury.

Methods

After familiarisation, 14 males (age: 33 ± 7 years; V̇O_2peak: 57.1 ± 8.6 ml/kg/min; mean ± SD) completed 2 trials in a randomised cross-over design, each involving 6, 15 min blocks of shuttle running (modified Loughborough Intermittent Shuttle Test protocol) in temperate conditions (22.3 ± 1.0 °C; 47.9 ± 12.9% relative humidity). During exercise, subjects consumed either a volume of water equal to 90% of sweat losses (EU) or 75 mL water (HYP). Body mass, blood and urine samples were taken pre-exercise (baseline/pre), 30 min post-exercise (post) and 24 h post-baseline (24 h).

Results

Post-exercise, body mass loss, serum osmolality and urine osmolality were greater in HYP than EU (P ≤ 0.024). Osmolality-corrected urinary kidney injury molecule-1 (uKIM-1) concentrations were increased post-exercise (P ≤ 0.048), with greater concentrations in HYP than EU (HYP: 2.76 [1.72–4.65] ng/mOsm; EU: 1.94 [1.1–2.54] ng/mOsm; P = 0.003; median [interquartile range]). Osmolality-corrected urinary neutrophil gelatinase-associated lipocalin (uNGAL) concentrations were increased post-exercise (P < 0.001), but there was no trial by time interaction effect (P = 0.073).

Conclusion

These results suggest that hypohydration produced by high-intensity intermittent running increases renal injury, compared to when euhydration is maintained, and that the site of this increased renal injury is at the proximal tubules.

Efficacy and Safety of Isotonic and Hypotonic Intravenous Maintenance Fluids in Hospitalised Children: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Hyponatraemia is a known complication in hospitalised children receiving maintenance intravenous fluid. Several studies have been published to investigate the efficacy and safety of intravenous fluids in children. However, there is still an ongoing debate regarding the ideal solution to be used in the paediatric population. Therefore, the aim of this meta-analysis was to investigate the safety and efficacy of administering isotonic versus hypotonic intravenous maintenance fluid in hospitalised children. An extensive search was undertaken on PubMed, Web of Science, Scopus, ScienceDirect, Google Scholar and Cochrane Library on 28 December 2020. Only randomised controlled trials (RCTs) were included. We used the random-effects model for all analyses. Risk ratio (RR) and mean difference with 95% confidence intervals (CIs) were used for dichotomous and continuous outcomes, respectively. The quality of each study was assessed using the Joanna Briggs Institute critical appraisal tool for RCTs. This study is registered with PROSPERO (CRD42021229067). Twenty-two RCTs with a total of 3795 participants were included. The studies encompassed surgical and medical patients admitted to intensive care unit as well as to general wards. We found that hypotonic fluid significantly increases the risk of hyponatremia at both ≤24 h (RR 0.34; 95% CI: 0.26–0.43, p < 0.00001) and >24 h (RR 0.48; 95% CI: 0.36–0.64, p < 0.00001). Isotonic fluid increases the risk of hypernatraemia at ≤24 h (RR 2.15; 95% CI: 1.24–3.73, p = 0.006). The prevalence of hyponatraemia was also higher in the hypotonic group at both ≤24 h (5.7% vs. 23.3%) and >24 h (6.0% vs. 26.3%). There was no statistically significant difference in the risk of developing adverse outcomes between the two groups. Mean serum and urine sodium as well as serum osmolality/osmolarity was lower in the hypotonic group. Isotonic solution is protective against the development of hyponatraemia while hypotonic solution increases the risk of hyponatraemia.

Relation between hyponatraemia and falls by acute hospitalised patients: A case-control study

AIMS AND OBJECTIVES

To investigate the possible association between hyponatremia and falls, in a sample of hospitalised adult patients.

BACKGROUND

In-hospital falls are a problem of major importance, provoking a significant decline in the quality of life of many patients. Recent studies have identified a relationship between such falls and the presence of hyponatremia.

DESIGN

Analytical retrospective observational case-control study.

METHODS

The study population consisted of hospitalised patients who had suffered an in-hospital fall during the period 2014-2016. For each case, two controls who had not suffered any such fall were recruited. These cases and controls were matched according to gender, age, hospitalisation unit and date of admission. Study data were obtained from the hospital's record of falls, regarding the patients' socio-demographic factors, physical and psychological conditions and blood levels of sodium, potassium, urea and creatinine. The study is reported in accordance with STrengthening the Reporting of OBservational studies in Epidemiology guidelines.

RESULTS

The study sample consisted of 555 patients (185 cases and 370 controls). Hyponatraemia was detected in 57 cases (30.8%). A statistically significant relationship was found between the presence of hyponatraemia and the occurrence of falls: OR = 2.04. Other risk factors for falls were hypercreatinaemia OR 2.49, hyperuraemia OR 1.82, disorientation, need for ambulatory assistance and longer hospital stay.

CONCLUSIONS

From the study findings, we conclude that hyponatraemia is a predictor of falls by acute hospitalised patients. Further research is needed on the relationship between hypercreatinaemia, hyperuraemia and falls.

RELEVANCE TO CLINICAL PRACTICE

The assessment of risk factors for falls, such as hyponatraemia, can alert us to the possibility of this event occurring and facilitate the implementation of preventive measures. This parameter should be included as a significant new factor in assessment instruments designed to assess the risk of falls, thus enhancing the reliability and diagnostic validity of these instruments.

Molecular and physical technologies for monitoring fluid and electrolyte imbalance: A focus on cancer population

Several clinical examinations have shown the essential impact of monitoring (de)hydration (fluid and electrolyte imbalance) in cancer patients. There are multiple risk factors associated with (de)hydration, including aging, excessive or lack of fluid consumption in sports, alcohol consumption, hot weather, diabetes insipidus, vomiting, diarrhea, cancer, radiation, chemotherapy, and use of diuretics. Fluid and electrolyte imbalance mainly involves alterations in the levels of sodium, potassium, calcium, and magnesium in extracellular fluids. Hyponatremia is a common condition among individuals with cancer (62% of cases), along with hypokalemia (40%), hypophosphatemia (32%), hypomagnesemia (17%), hypocalcemia (12%), and hypernatremia (1-5%). Lack of hydration and monitoring of hydration status can lead to severe complications, such as nausea/vomiting, diarrhea, fatigue, seizures, cell swelling or shrinking, kidney failure, shock, coma, and even death. This article aims to review the current (de)hydration (fluid and electrolyte imbalance) monitoring technologies focusing on cancer. First, we discuss the physiological and pathophysiological implications of fluid and electrolyte imbalance in cancer patients. Second, we explore the different molecular and physical monitoring methods used to measure fluid and electrolyte imbalance and the measurement challenges in diverse populations. Hydration status is assessed in various indices; plasma, sweat, tear, saliva, urine, body mass, interstitial fluid, and skin-integration techniques have been extensively investigated. No unified (de)hydration (fluid and electrolyte imbalance) monitoring technology exists for different populations (including sports, elderly, children, and cancer). Establishing novel methods and technologies to facilitate and unify measurements of hydration status represents an excellent opportunity to develop impactful new approaches for patient care.

Serum sodium in relation to various domains of cognitive function in the elderly US population

Background

Recent evidence suggests that sodium imbalances may be associated with cognitive impairment; however, the association between specific domains of cognition remains unclear. This study examines the association between serum sodium levels and immediate and delayed verbal memory as measured by the CERAD Word Learning Test (CERAD WLT), executive function as measured by the Animal Fluency test (AFT), and sustained attention, working memory, and processing speed as measured by the Digit Symbol Substitution test (DSST) in the elderly population of the US aged 60 and older who participated in the 2011–2014 National Health and Nutrition Examination Surveys (n = 2,541).

Methods

Cognitive function tests were performed by trained interviewers and sodium levels were measured using indirect ion selective electrode methodology.

Results

After adjusting for all covariates, quintiles of CERAD WLT scores showed significant positive associations with log-transformed sodium levels (Immediate recall (IR) β = 4.25 (SE = 1.83, p-value 0.027); Delayed recall (DR) β = 6.54 (SE = 1.82, p-value 0.001)). Compared to normal sodium levels, hyponatremia was significantly associated with lower CERAD WLT-IR (β = -0.34, SE = 0.15, p-value 0.035) and CERAD WLT-DR scores (β -0.48, SE = 0.10, p-value < 0.001) and showed borderline significance with AFT scores (β = = -0.38, SE = 0.19, p-value 0.052). Hypernatremia did not show any significant relationships with cognitive test scores, compared to normal sodium levels.

Conclusions

Our cross-sectional study showed that lower sodium levels were associated with cognitive change, especially regarding memory and executive function.

Severe hyponatremia in children: a review of the literature through instructive cases

Hyponatriemia is the most common electrolyte disorder in the paediatric population. Symptoms are related to the time in which hyponatriemia has developed. The acute presentation could be dramatic, with neurological symptoms like headache, seizure, impaired mental status and even coma. It is essential for the physician to be aware of the possible causes of hyponatremia in the child in order to start a prompt treatment.

A Case Report of Severe Hyponatremia Secondary to Coronavirus Disease 2019 Viral Pneumonia

As of December 2020, the coronavirus disease 2019 (COVID-19) pandemic has resulted in 82.2 million cases worldwide. We report the case of a 69-year-old South Asian female with a history of hypertension, hypothyroidism, meningiomatosis, and urinary incontinence who contracted COVID-19 and developed severe hyponatremia. She was initially medically managed with antibiotics, anti-parasitics, anti-coagulants, and steroids. After experiencing breathlessness, chest discomfort, high systolic blood pressure, and tachycardia, she was admitted and diagnosed with post-COVID pneumonia, and was conservatively treated with steroids. She showed improvement, and was discharged upon being declared hemodynamically stable. While the patient was at home, she experienced periods of breathlessness and acral edema. This case raises the question of the correlation between hyponatremia and COVID-19, especially in regards to symptomatic presentations, including altered mental status, headache, and nausea. As there are limited studies that show severe electrolyte disorders leading to mortality, more research is needed to understand hyponatremia in cases with COVID-19.

Level of natremia as an index of the condition of the organism of animals under stress

In the diagnosis of stressful conditions in humans and other animals, ionic indicators remain practically unused. In this work, we studied the changes in the concentrations of sodium ions in the blood plasma of freshwater fish under stress caused by stressors of different quality and quantity. Most of the experiments were carried out on adult bream (Abramis brama L) from the Rybinsk Reservoir. Separate experiments were duplicated on adult individuals of roach (Rutilus rutilus L.), pike (Esox lucius L.), and blue bream (Abramis ballerus L.). The concentration of cations in the blood plasma was determined using a Flapho-4 flame photometer. Under the action of mild and short-term stressors of different qualities, the sodium concentration in the internal environment altered toward an increase in concentration gradients on the cell membrane (eustress or physiological stress). Hypernatremia was approximately 10%. Under the action of strong and/or prolonged stressors of different strength, the sodium concentration in the internal environment changed toward a decrease in concentration gradients on the cell membrane (distress or pathological stress). Hyponatremia was 50% in the conditions of acute lethal stress, 20% in subacute lethal stress, 10% or more in chronic lethal stress. During strong acute reversible stress, hyponatremia could reach 30%. Analysis of the material on mammals allowed us to conclude that the adaptation mechanisms in fish and higher vertebrates are similar. In this work, for the first time, the state of the system of electrolyte balance of animals under stress was analyzed from the standpoint of the leading role of ionic concentration gradients on the cell membrane (mainly sodium) in the energetics (level of disequilibrium) of the organism. We propose a concept that in normal and extreme conditions fish use two different defense reactions (or adaptation strategies): active and passive, consisting, respectively, in increasing or decreasing the level of disequilibrium (energy) in the organism. The hyponatremia recorded by numerous authors, which accompanies diseases in humans, is evidently a nonspecific reaction of the organism and serves as an indicator of reduced energy of the organism. It is suggested that the sodium level in the internal environment of the organism be used for diagnosing the stress state of animals.

Surgical treatment of a 72-year-old patient with headache, hyponatremia and oculomotor nerve palsy: a case report and literature review

Pituitary apoplexy is a life-threatening syndrome caused by acute infarction of the pituitary gland. The most common symptoms associated with pituitary apoplexy are headache, nausea, vomiting, visual symptoms, hypopituitarism, and altered mental status. Both oculomotor nerve palsy and hyponatremia are relatively rare complications of pituitary apoplexy. The treatment of pituitary apoplexy is controversial. We report a case of a 72-year-old man with severe headache, nausea, vomiting, confusion and left oculomotor nerve palsy, who was initially considered as posterior communicating artery aneurysm (PCOAA) based on the presenting symptoms. Initial biochemical evaluation showed severe hyponatremia, hormonal evaluation identified multiple pituitary hormone deficiency and enhanced magnetic resonance imaging showed a large pituitary adenoma with signs of hemorrhage. A diagnosis of pituitary apoplexy and secondary hypopituitarism was finally made. The patient was treated with intravenous hydrocortisone 100 mg twice daily and oral levothyroxine 100 mg once daily. Appropriate venous transfusion with sodium was also used concomitantly to correct hyponatremia. After seven days of treatment, the patient's serum electrolytes normalized and he gradually recovered alertness. Then, the patient underwent transsphenoidal surgery for tumor removal. Left ptosis and oculomotor nerve palsy completely recovered three months after surgery. Postoperatively, hormone replacement therapy was essential for the patient with 20 mg hydrocortisone and 50 mg levothyroxine once daily. During the last follow up 4 years later, the patient was still on hormonal replacement and in good condition. So, for patients with pituitary apoplexy, we have shown that a semi-elective surgery after conservative treatment when the patient becomes clinically stable and hypopituitarism has been corrected is a good approach.

Symptomatic Hyponatremia following Bowel Preparation for Colonoscopy: A Case Report

Colonoscopy is considered a gold standard tool for the diagnostic evaluation of colorectal diseases. Bowel preparation, a pre-requisite for colonoscopy, usually involves ingestion of purgatives for the cleansing of the bowel so that visualization is not obscured during the procedure. Commonly used preparations are sodium phosphate-based solutions, sodium picosulphate and polyethylene glycol. The use of such preparations is associated with electrolyte disturbances, commonly hyponatremia. Hyponatremia is usually seen with sodium phosphate based solutions and is rare with polyethylene glycol. Symptomatic hyponatremia, however, is rare following bowel preparation and is attributable to other factors as well, such as the age of patient, non-osmotic release of antidiuretic hormone and the procedure itself. In this report, we discuss a case of severe symptomatic hyponatremia observed in a 71-year-old gentleman who underwent polyethylene glycol based bowel preparation for colonoscopy.

Hyponatremia in Patients with Hematologic Diseases

Hyponatremia is the most common electrolyte disorder in clinical practice and is associated with increased morbidity and mortality. It is frequently encountered in hematologic patients with either benign or malignant diseases. Several underlying mechanisms, such as hypovolemia, infections, toxins, renal, endocrine, cardiac, and liver disorders, as well as the use of certain drugs appear to be involved in the development or the persistence of hyponatremia. This review describes the pathophysiology of hyponatremia and discusses thoroughly the contributing factors and mechanisms that may be encountered specifically in patients with hematologic disorders. The involvement of the syndrome of inappropriate antidiuretic hormone (SIADH) secretion and renal salt wasting syndrome (RSWS) in the development of hyponatremia in such patients, as well as their differential diagnosis and management, are also presented. Furthermore, the distinction between true hyponatremia and pseudohyponatremia is explained. Finally, a practical algorithm for the evaluation of hyponatremia in hematologic patients, as well as the principles of hyponatremia management, are included in this review.