Epidemiology and characteristics of hyponatremia in the emergency department

Hyponatremia in the emergency department: an overview of diagnostic and therapeutic approach

INTRODUCTION

Hyponatremia, defined as a serum sodium concentration <135 mmol/l, is a frequent electrolyte disorder in patients presenting to an emergency department (ED). In this context, appropriate diagnostic and therapeutic management is rarely performed and challenging due to complex pathophysiologic mechanisms and a variety of underlying diseases.

OBJECTIVE

To implement a feasible pathway of central diagnostic and therapeutic steps in the setting of an ED.

METHODS

We conducted a narrative review of the literature, considering current practice guidelines on diagnosis and treatment of hyponatremia. Underlying pathophysiologic mechanisms and management of adverse treatment effects are outlined. We also report four cases observed in our ED.

RESULTS

Symptoms associated with hyponatremia may appear unspecific and range from mild cognitive deficits to seizures and coma. The severity of hyponatremia-induced neurological manifestation and the risk of poor outcome is mainly driven by the rapidity of serum sodium decrease. Therefore, emergency treatment of hyponatremia should be guided by symptom severity and the assumed onset of hyponatremia development, distinguishing acute (<48 hours) versus chronic hyponatremia (>48 hours).

CONCLUSIONS

Especially in moderately or severely symptomatic patients presenting to an ED, the application of a standard management approach appears to be critical to improve overall outcome. Furthermore, an adequate work-up in the ED enables further diagnostic and therapeutic evaluation during hospitalization.

Mortality predictors of patients diagnosed with severe hyponatremia in the emergency department

PURPOSE

To determine the factors affecting mortality as a result of the analysis of the demographic and clinical characteristics and laboratory parameters of patients whose serum Na value was determined to be 125 mEq/L or below at the time of admission to the emergency department (ED).

METHOD

Patients over 18 years of age who admitted to the ED of a tertiary hospital between September 2021 and September 2022 and whose serum sodium level was determined to be 125 mEq/L and below were included in the study. Demographic and clinical characteristics, admission complaints, medications used, Charles comorbidity index (CCI), laboratory parameters, and outcomes of the patients included in the study were recorded in the data form.

RESULTS

Three hundred ninety-nine patients were included in the study. When the 30-day mortality of the patients is examined, the mortality rate was found to be 21.6%. In the analyses performed for the predictive power of laboratory parameters for mortality, it was determined that the highest predictive power among the predictive values determined by the area under the curve (AUC) was the albumin level (AUC 0.801, 95% CI 0.753-0.849, p < 0.001). In the binary logistic regression analysis, urea and albumin were independent predictors of 30-day mortality.

CONCLUSION

According to study data, albumin and urea levels are independent predictors of 30-day mortality in patients diagnosed with severe hyponatremia in the emergency department.

Prevalence, Risk Factors, and Mortality of Patients Presenting with Moderate and Severe Hyponatremia in Emergency Departments

Background

Hyponatremia is among the most common electrolyte disturbances encountered in clinical practice and is associated with a high rate of morbidity and mortality. However, there are very limited data on adult cases presenting to emergency departments with hyponatremia.

Objectives

This study aimed to evaluate the frequency, clinical characteristics, and outcomes in hyponatremic patients presenting to emergency departments.

Methods

This retrospective study analyzed all patients older than 18 years who visited our institution's emergency department between October 2018 and October 2019 and has a serum sodium (Na) level <130 mmol/L.

Results

Among 24,982 patients who visited the emergency department and had a documented serum sodium level, 284 were included. Patients' median age was 67.13 ± 14.8 years. Younger patients are less likely to develop severe hyponatremia compared to older patients (adjusted odds ratio (AOR): 0.415; 95% confidence interval (CI): 0.231-0.743; p=0.003). Asymptomatic hyponatremia and gastrointestinal manifestations were the most common presenting hyponatremia symptoms (33.7% and 24.2%, respectively). Proton pump inhibitor (PPI) use, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACE/ARB) use, and spironolactone use (OR = 2.6 and 3.9, 2.3 with a p=0.02, 0.03, and 0.05, respectively) were associated with increased odds of severe hyponatremia. There is no difference in the overall mortality rate within 6 months of presentation between severe and moderate hyponatremia groups (11.1% versus 16.2%, p=0.163).

Conclusion

Moderate and severe hyponatremia are not uncommon among patients presenting to emergency departments. Moderate hyponatremia can be asymptomatic with clinical significance. Older patients, use of PPI, use of ACEi/ARBs, and spironolactone use were associated with an increased risk of severe hyponatremia compared to moderate. Further prospective analysis of a larger population is needed to confirm our findings.

The Association between Dysnatraemia during Hospitalisation and Post-COVID-19 Mental Fatigue

COVID-19 may induce short- and long-term cognitive failures after recovery, but the underlying risk factors are still controversial. Here, we investigated whether (i) the odds of experiencing persistent cognitive failures differ based on the patients' disease course severity and sex at birth; and (ii) the patients' electrolytic profile in the acute stage represents a risk factor for persistent cognitive failures. We analysed data from 204 patients suffering from COVID-19 and hospitalised during the first pandemic wave. According to the 7-point WHO-OS scale, their disease course was classified as severe or mild. We investigated the presence of persistent cognitive failures collected after hospital discharge, while electrolyte profiles were collected during hospitalisation. The results showed that females who suffered from a mild course compared to a severe course of COVID-19 had a higher risk of presenting with persistent mental fatigue after recovery. Furthermore, in females who suffered from a mild course of COVID-19, persistent mental fatigue was related to electrolyte imbalance, in terms of both hypo- and hypernatremia, during hospitalisation in the acute phase. These findings have important implications for the clinical management of hospitalised COVID-19 patients. Attention should be paid to potential electrolyte imbalances, mainly in females suffering from mild COVID-19.

Diagnostic Workup and Outcome in Patients with Profound Hyponatremia

Hyponatremia is the most common electrolyte disorder. A proper diagnosis is important for its successful management, especially in profound hyponatremia. The European hyponatremia guidelines point at sodium and osmolality measurement in plasma and urine, and the clinical evaluation of volume status as the minimum diagnostic workup for the diagnosis of hyponatremia. We aimed to determine compliance with guidelines and to investigate possible associations with patient outcomes. In this retrospective study, we analysed the management of 263 patients hospitalised with profound hyponatremia at a Swiss teaching hospital between October 2019 and March 2021. We compared patients with a complete minimum diagnostic workup (D-Group) to patients without (N-Group). A minimum diagnostic workup was performed in 65.5% of patients and 13.7% did not receive any treatment for hyponatremia or an underlying cause. The twelve-month survival did not show statistically significant differences between the groups (HR 1.1, 95%-CI: 0.58-2.12, p-value 0.680). The chance of receiving treatment for hyponatremia was higher in the D-group vs. N-Group (91.9% vs. 75.8%, p-value < 0.001). A multivariate analysis showed significantly better survival for treated patients compared to not treated (HR 0.37, 95%-CI: 0.17-0.78, p-value 0.009). More efforts should be made to ensure treatment of profound hyponatremia in hospitalised patients.

Retrospective analysis of patients diagnosed with severe hyponatraemia in the emergency department

Background . We investigated the demographic, aetiological and clinical characteristics of patients who presented to the emergency department and had severe hyponatraemia. Methods . We retrospectively evaluated 1171 patients who presented to the emergency department and were diagnosed with severe hyponatraemia. Results . Over half the patients studied were women (53.5%). The mean age of women was higher (p<0.0001). The most common complaint was dyspnoea (16.8%) and 42.5% of the patients had an oral intake disorder. In addition, 22.3% of the patients were on loop diuretics. About 76.3% of patients were conscious, and the mean sodium level of these patients was higher than the mean sodium level of those who responded to verbal and painful stimuli (p<0.001). Severe isolated hyponatraemia was observed in 61.8% of the patients. The mortality rate was 12.8%. There was no difference between the mean sodium levels of the deceased and discharged patients (p=1.0). The mortality rate was higher in patients who had a history of cirrhosis and cancer, but was lower in patients with a history of coronary artery disease (p=0.0002, p<0.0001 and p=0.04, respectively). Conclusion . Severe hyponatraemia was more prevalent in women, serum sodium levels were higher in conscious patients, and the mortality rate was higher in patients who had a history of cirrhosis and cancer. We found that the mean serum sodium levels did not help in distinguishing between the deceased and discharged patients.

Severe hyponatraemia (P-Na < 116 mmol/l) in the emergency department: a series of 394 cases

AIM

To evaluate the significance of severe hyponatraemia presented at the emergency department (ED).

METHODS

A retrospective hospital records study of all patients with plasma sodium levels of < 116 mmol/l from 2016 to 2020 in a single tertiary referral centre.

RESULTS

A total of 394 visits of 363 individual severely hyponatraemic patients represented 0.08% of all ED visits. The mean age was 68 years and the male-to-female ratio was 1:1.3. The symptoms and signs were diffuse and varying, while half of the patients had neurologic symptoms. The aetiology of hyponatraemia was often multifactorial. The aetiologies varied by age, and the most common ones were the syndrome of inappropriate antidiuresis (34%), diuretic use (27%), alcohol-related (19%) and dehydration (19%). The mean sodium correction rates were 6.6, 4.9 and 3.8 mmol/l/24 h at 24, 48 and 72 h, respectively. The mean maximum correction rate over any 24-h time interval was 10.2 mmol/l. The vital signs (National Early Warning Score, NEWS) of severely hyponatraemic patients were mostly normal. All-cause mortality was 18% for 1-year follow-up. Malignancies, especially small-cell lung cancer, and end-stage liver disease caused most of the deaths. Osmotic demyelination syndrome (ODS) was diagnosed in five (1.4%) patients.

CONCLUSION

Patients with severe hyponatraemia in the ED presented with non-specific complaints. The aetiology of hyponatraemia was often multifactorial and varied by age. The need for intensive care was poorly predicted by NEWS. The one-year mortality rate was 18% and the incidence of ODS 1.4% after an episode of severe hyponatraemia.

The Association Between Hyponatremia and Optic Nerve Sheath Diameter: A Prospective Study

Background Hyponatremia is a common electrolyte balance disorder. It may result in brain edema and increased intracranial pressure (ICP). Optic nerve sheath diameter (ONSD) measurement remains an increasingly sought-after method in many situations associated with ICP elevations. The aim of our study was to investigate the relationship between the change of ONSD before and after hypertonic saline (3% sodium chloride) treatment and the clinical improvement with increased sodium levels in patients with symptomatic hyponatremia who presented to the emergency department. Methodology This study was conducted in the emergency department of a tertiary hospital, according to the design of a prospective, self-controlled, non-randomized trial study. Determined by power analysis, 60 patients were included in the study. The statistical analysis of the continuous data was performed using the means, standard deviations, and minimum and maximum values of the feature values. The frequency and percentage values were used to define categorical variables. The mean difference comparison of pre-and post-treatment measurements was evaluated by paired t-test. P<0.05 was considered to be significant. Results The measurement parameters' differences before and after hypertonic saline treatment were evaluated. While the mean of the right eye ONSD was 5.27±0.22 mm before treatment, it declined substantially to 4.52±0.24 mm after treatment (p<0.001). It was also found that the left eye ONSD was 5.26±0.23 mm before the treatment and declined to 4.53±0.24 mm after the treatment (p<0.001). In addition, the mean of the overall ONSD was 5.26±0.23 mm before treatment and 4.52±0.24 mm after treatment (p<0.001). Conclusions Ultrasonic measurement of ONSD can be used to monitor the clinical improvement of patients receiving hypertonic saline therapy for symptomatic hyponatremia.

Hyponatremia in the emergency department

Hyponatremia, defined as a serum sodium <135 mmol/L, is frequently encountered in patients presenting to the emergency department. Symptoms are often unspecific and include a recent history of falls, weakness and vertigo. Common causes of hyponatremia include diuretics, heart failure as well as Syndrome of Inappropriate Antidiuresis (SIAD) and correct diagnosis can be challenging. Emergency treatment of hyponatremia should be guided by presence of symptoms and focus on distinguishing between acute and chronic hyponatremia.

Current and Future Burdens of Heat-Related Hyponatremia: A Nationwide Register-Based Study

CONTEXT

A seasonal variation in hyponatremia, with higher incidence rates during hot summer days, has been demonstrated. Whether this applies to cool temperate regions is currently unknown.

OBJECTIVE

The aim of this study was to investigate the influence of ambient temperature on hyponatremia in the Swedish population under current and future climate scenarios.

METHODS

This nationwide cohort study identified all patients hospitalized with a first-ever principal diagnosis of hyponatremia between October 2005 and December 2014. Incidence rates for hyponatremia were calculated as number of hospitalizations divided by person-days at risk in the adult Swedish population at a given temperature, in increments of 1 °C.

RESULTS

The incidence of hyponatremia was stable at 0.3 per million person-days from -10 to 10 °C, but increased rapidly at 24-hour mean temperatures above 15 °C, with 2.26 hospitalizations per million days at the highest recorded temperature of 25 °C. Women and elderly carried the greatest risk, with an incidence of 35 hospitalizations per million days in individuals ≥ 80 years of age on the hottest days, corresponding to a 15-fold increase in incidence compared with cool days. A future 1 or 2 °C increase in mean temperature is expected to increase the incidence of hyponatremia by 6.3% and 13.9%, respectively.

CONCLUSION

The risk of hospitalization due to hyponatremia increases rapidly at temperatures above 15 °C, indicating a threshold effect. Over the next decades, rising global temperatures are expected to increase the inpatient burden of hyponatremia by approximately 10%. Strategies for protecting vulnerable groups are necessary to reduce this risk.

Risk factors and mortality in elderly patients with severe hyponatremia admitted to the emergency department

BACKGROUND

This study was aimed at determining the risk factors associated with mortality in elderly patients with severe hyponatremia admitted to the emergency department.

MATERIALS AND METHODS

The data of patients aged ≥ 65 years who were admitted to the emergency department and whose serum sodium levels were < 125 mEq/L were retrospectively collected.

RESULTS

Mortality was associated with chronic liver disease/cirrhosis (p = 0.036), metastatic tumor (p = 0.007) and solid tumor (p = 0.013) cancers, antiarrhythmic drug use (p = 0.003), potassium-sparing diuretic use (p = 0.044), antineoplastic drug use (p = 0.0029), and dialysis treatment (p = 0.015). The following cutoff values were determined to be predictive of mortality: urea > 63.6 (AUC: 0.771; p = 0.0001), creatinine > 1.39 (AUC: 0.675; p = 0.0003), potassium > 4.64 (AUC: 0.711; p = 0.0001), C-reactive protein > 44 (AUC: 0.765; p = 0.0001), white blood cell count > 12.21 (AUC: 0.688; p = 0.0001), hemoglobin < 11.2 (AUC: 0.611; p = 0.0103), and Charlson comorbidity index > 2 (AUC: 0.739; p = 0.0001). The use of antineoplastic drugs (OR: 4.502; p = 0.010) and increased values of the following were associated with an increased risk of mortality: urea (OR: 1.007; p = 0.024), C-reactive protein (OR: 1.005; p = 0.026), glucose (OR: 1.008; p = 0.001), and Charlson comorbidity index (OR: 1.198; p = 0.025).

CONCLUSION

Malignancy; liver cirrhosis; dialysis treatment; increased Charlson comorbidity index, urea, and C-reactive protein values and the use of antineoplastic drugs are associated with mortality.

Thiazide-associated hyponatremia in internal medicine patients: analysis of epidemiological and biochemical profiles

Thiazide-associated hyponatremia (TAH) is a clinically important side effect of the therapy with thiazide and thiazide-like diuretics. This study aims to analyze epidemiological, biochemical, and symptomatological profiles (including volume status) of patients admitted with TAH. A retrospective hospital record study was performed. Epidemiological and biochemical parameters and symptoms were compared between the thiazide (n = 143) and non-thiazide (n = 282) groups. Patients in the thiazide group were classified as hypo-, normo-, or hypervolemic. Furthermore, the comparison of epidemiological, biochemical, partially pharmacotherapeutical, and symptomatological parameters between the hypovolemic and normovolemic groups was performed. The thiazide group showed lower s-Na (p = 0.008), s-K (p <0.001), s-Cl (p <0.001), measured s-osmolality (p = 0.021), and eGFR (p <0.001); higher s-urea (p <0.001), s-creatinine (p = 0.023), s-glucose (p <0.001), u-osmolality (p = 0.012), u-Na (p <0.001), u-K (p = 0.023), and u-Cl (p <0.001). Patients using thiazide were older (p <0.001), more likely to be female (p = 0.011), and with symptoms corresponding more to chronic hyponatremia. Compared to the normovolemic group (n = 93; 65%), the hypovolemic patients (n = 47; 32.9%) showed higher s-urea (p = 0.005), s-creatinine (p = 0.045), and s-UA (p = 0.010); lower eGFR (p = 0.032), u-Na (p = 0.015), u-Cl (p = 0.016), anorexia (p <0.001), and a higher frequency of furosemide use (p <0.001). Thiazide use is a crucial etiological cause of hypotonic hyponatremia among internal medicine inpatients, associated with more severe hyponatremia, but with no difference in the in-hospital mortality. Even in hypo-osmolar conditions of TAH, 32.9% of patients exhibited signs of volume depletion. FE-UA did not differ between the hypovolemic and the normovolemic patients in TAH conditions. Anorexia and the combination of thiazide together with furosemide, rather than thiazide use alone, were risk factors for hypovolemic hyponatremia without affecting FE-UA.

Prevalence of adrenal insufficiency among patients with euvolemic hyponatremia

BACKGROUND

The diagnosis of syndrome of inappropriate anti-diuresis requires the exclusion of secondary adrenal insufficiency (AI) among patients with euvolemic hyponatremia (EuVHNa). Studies have suggested that about 2.7-3.8% of unselected patients presenting to the emergency room with EuVHNa have undiagnosed AI and it is as high as 15% among patients admitted to specialized units for evaluation of hyponatremia.

OBJECTIVE

To study the prevalence of AI among in-patients with EuVHNa in a general medical ward setting.

METHODS

This was a prospective, single-center observational study conducted among general medical in-patients with EuVHNa, defined as patients with a serum sodium <135 mmol/L, clinical euvolemia and urine spot sodium >30 mmol/L. Additionally, patients with recent vomiting, current renal failure, diuretic use and those with uncontrolled hyperglycemia were excluded. Adrenal functions were assessed by a modified adrenocorticotropic hormone (ACTH) stimulation test called the Acton Prolongatum™ stimulation test (APST). A cut-off cortisol value of <18 mg/dL after 60 min of ACTH injection was used to diagnose AI.

RESULTS

One hundred forty-one patients were included and underwent an APST. APST suggested 20/141 (14.2%) had undiagnosed AI. The commonest cause of AI (9/20) was secondary AI because of the use of steroids including inhaled steroids and indigenous medicines contaminated with steroids. In 5 (3.5%) patients hypopituitarism was newly diagnosed. Despite primary AI (PAI) not commonly presenting as EuVHNa, 2/20 patients had PAI.

CONCLUSIONS

AI is much commoner in our country, among in-patients with EuVHNa primarily driven by exogenous steroid use and undiagnosed hypopituitarism.

Association between lipid-lowering agents and severe hyponatremia: a population-based case-control study

PURPOSE

Drug-induced hyponatremia is common, with medications from many drug-classes implicated. Lipid-lowering agents are among the most prescribed drugs. Limited evidence suggests an inverse association between statins and hyponatremia, while data on other lipid-lowering agents is absent. The objective of this investigation was to study the association between lipid-lowering drugs and hospitalization due to hyponatremia.

METHODS

This was a register-based case-control study of the general Swedish population. Those hospitalized with a main diagnosis of hyponatremia (n = 11,213) were compared with matched controls (n = 44,801). Multivariable logistic regression adjusting for co-medication, diseases, previous hospitalizations, and socioeconomic factors was used to explore the association between severe hyponatremia and the use of lipid-lowering drugs.

RESULTS

Unadjusted ORs (95% CI) for hospitalization due to hyponatremia were 1.28 (1.22-1.35) for statins, 1.09 (0.79-1.47) for ezetimibe, 1.38 (0.88-2.12) for fibrates, and 2.12 (1.31-3.35) for resins. After adjustment for confounding factors the adjusted odds ratios (95% CI) compared with controls were 0.69 (0.64-0.74) for statins, 0.60 (0.41-0.86) for ezetimibe, 0.87 (0.51-1.42) for fibrates, and 1.21 (0.69-2.06) for resins.

CONCLUSIONS

Use of statins and ezetimibe was inversely correlated with severe hyponatremia. Consequently, these drugs are unlikely culprits in patients with hyponatremia, and they appear safe to initiate in hyponatremic patients. A potential protective effect warrants further studies on how statins and other lipid-lowering drugs are linked to dysnatremias.

Associations Between Antihypertensive Medications and Severe Hyponatremia: A Swedish Population-Based Case-Control Study

BACKGROUND

Calcium channel blockers (CCBs), beta-receptor blockers (BBs), angiotensin-converting enzyme inhibitors (ACEIs), and angiotensin II receptor blockers (ARBs) have occasionally been reported to cause severe hyponatremia. The aim was to explore the association between CCBs, BBs, ACEIs, and ARBs and hospitalization due to hyponatremia.

METHODS

Patients hospitalized with a principal diagnosis of hyponatremia (n = 11 213) were compared with matched controls (n = 44 801). Linkage of national population-based registers was used to acquire data. Multivariable logistic regression adjusting for co-medications, diseases, previous hospitalizations, and socioeconomic factors was used to explore the association between hospitalization for severe hyponatremia and the use of different CCBs, BBs, ACEIs, and ARBs. Furthermore, newly initiated (≤90 days) and ongoing use were examined separately.

RESULTS

Adjusted odds ratios (aORs) (95% confidence interval) for the investigated 4 drug classes ranged from 0.86 (0.81-0.92) for CCBs to 1.15 (1.07-1.23) for ARBs. For newly initiated drugs, aORs spanned from 1.64 (1.35-1.98) for CCBs to 2.24 (1.87-2.68) for ACEIs. In contrast, the corresponding associations for ongoing therapy were not elevated, ranging from 0.81 (0.75-0.86) for CCBs to 1.08 (1.00-1.16) for ARBs. In the CCBs subgroups, aOR for newly initiated vascular CCBs was 1.95 (1.62-2.34) whereas aOR for ongoing treatment was 0.82 (0.77-0.88).

CONCLUSIONS

For newly initiated CCBs, BBs, ACEIs, and ARBs, the risk of hospitalization due to hyponatremia was moderately elevated. In contrast, there was no evidence that ongoing treatment with investigated antihypertensive drugs increased the risk for hospitalization due to hyponatremia.

Admission glucose level was associated with increased short-term mortality and length-of-stay irrespective of diagnosis, treating medical specialty or concomitant laboratory values

BACKGROUND

Glucose is a routine emergency sample. General guidelines for inpatient hyperglycemia are scarce, except in myocardial infarction, stroke, and perioperative/ICU. Previous studies found admission glucose associated with increased mortality in specific conditions. Scandinavian data, and for general patients, are scarcer. We investigated admission glucose levels, 30-day mortality, and length-of-stay (LoS), in a Swedish hospital.

METHODS

From 8146 emergency visits data regarding age, gender, dates of admission, discharge and death, diagnoses, admission p-glucose, s-sodium, s-potassium, b-hemoglobin, b-WBC and s-CRP, was collected, and for 6283 information regarding diagnosis of diabetes the previous 5 years. Visits were grouped in hypoglycemia (≤4.0), normoglycemia (>4.0-≤7.0), modest (>7.0-≤11.1) and severe hyperglycemia (>11.1) mmol/l.

RESULTS

Short-term mortality was 1.5% in the normoglycemic, 2.6% in the hypoglycemic, 4.0-4.5% in modest and severe hyperglycemia, p < 0.001; Cox proportional hazard ratios (HR) for groups of patients without/with diabetes were 6.8; 1; 3.4; 4.4/7.3; 3.9; 4.0; 2.1 compared to the normoglycemic without diabetes (p 0.0001-0.05); adjusted for age, and concurrent levels of sodium, potassium, Hb, WBC and CRP 1.51 (1.07-2.1, p 0.02) with modest hyperglycemia, and 1.08 (0.60-1.95, p 0.80) in severe hyperglycemia. Mean LoS was 1.2 and 1.7 days longer with modest and severe hyperglycemia.

CONCLUSIONS

Short-term mortality increased substantially with admission hypo- and hyperglycemia for patients both with and without diabetes, irrespective of treating medical specialty, main discharge diagnosis, or concurrent laboratory values. Patients with diabetes (16%) were older, with higher glucose levels at admission, and with a different pattern of the association of admission glucose and mortality.

Prevalence and incidence of hyponatremia and their association with diuretic therapy: Results from North India

Introduction:

Hyponatremia is associated with substantial morbidity and mortality. Correct estimation of their prevalence, incidence and risk factors, especially the diuretics in Indian patients is important in determining preventive strategies.

Methods:

This multistage mixed methods-based study was conducted in a high-volume cardiac care center to ensure the correct estimation. Patients receiving oral diuretics on an outpatient basis and those admitted to hospital for hyponatremia were enrolled.

Results:

The prevalence of hyponatremia was 27% while the incidence rate was 18% and 29% after 3- and 6-month of the diuretic therapy. The highest rates of hyponatremia were observed in warm season (45%, 111 in 247 patients). Multivariate logistic regression analysis revealed that low solute and nutritious intake and edematous state were negatively correlated with serum sodium levels. Neither diarrhea/vomiting nor diuretic use were found to be associated with hyponatremia.

Conclusions:

Diuretics use was not associated with hyponatremia in adults in this population cohort. However, elderly people on diuretics are comparatively more likely to have hyponatremia. However, a randomized parallel arm trial comparing diuretics with other antihypertensives be done to establish whether diuretics are associated with hyponatremia in this patient population.

Prevalence and Clinical Significance of Hyponatremia in Pediatric Intensive Care

A retrospective chart review was conducted to estimate the prevalence and severity level of hyponatremia on admission at the pediatric intensive care unit (PICU) in a Saudi tertiary hospital. Hyponatremia was highly prevalent (67.2%) and severe hyponatremia was frequent among patients with Pediatric Risk of Mortality score > 10%. Severe hyponatremia was also associated with increased length of stay ( p  = 0.04) and a trend of increased mortality ( p  = 0.054). However, disease severity was not an independent risk factor of mortality in PICU, but might confound other risk factors that render the children requiring prolonged hospital stay, mechanical ventilation, and increased health costs.

Hyponatremia: Prevalence and characteristics in internal medicine patients in southeast of China

To determine the incidence, clinical features, etiology, risk factors, and mortality in internal medicine patients with hyponatremia (P-Na).A prospective survey was conducted in patients with P-Na, diagnosed at admission in an Internal Medicine Department. 692 patients were then selected and subsequently divided into 3 groups based on the severity of P-Na. Multivariate linear regression analysis was used to explore the factors associated with levels of P-Na.The prevalence of P-Na was 3.37%. Euvolemia P-Na was the predominant subtype in 3 types of P-Na (49.42%). Gastrointestinal and neurological manifestations were common hyponatremic symptoms. The leading 5 underlying diagnoses were chest infection (31.94%), malignancy (10.84%), cardiac disease (6.36%), liver cirrhosis (6.07%), and neurological disease (5.20%). Moderate and severe P-Na had higher mortalities than mild P-Na (P <.05). For the levels of serum Na, Age, and serum Cl were positively correlated while serum K, blood urea nitrogen (BUN), and Glu were negatively correlated (P <.05).P-Na is common in internal medicine and accompanied by other electrolyte disturbances, various symptoms/diagnoses, and increased mortalities with decreasing Na, which requires special attention in clinical practice.

Hyponatremia and activation of vasopressin secretion are both independently associated with 30-day mortality: results of a multicenter, observational study

BACKGROUND

Hyponatremia is a common feature of acute illness and associated with increased mortality. This may be explained by a stress-mediated activation of the vasopressin system with an increase in free-water reabsorption.

OBJECTIVES

To investigate whether the association between hyponatremia and mortality could be explained by activation of the vasopressin system.

METHODS

We prospectively enrolled adult, medical patients seeking emergency care in three centres in Switzerland, France and the United States. We investigated associations between admission plasma sodium and copeptin, a stable portion of the vasopressin-precursor peptide, with 30-day mortality. We performed uni- and multivariate regression analysis.

RESULTS

Of 6962 included patients, 18% had hyponatremia (sodium ≤135 mmol L^-1 ), which doubled their risk for mortality compared to patients with normonatremia (8.3% vs. 3.8%). This association was confirmed in a multivariate-adjusted logistic regression analysis [adjusted odds ratio (OR) 1.47, 95% CI 1.12-1.93, P = 0.005]. Vasopressin levels, mirrored by copeptin, were also increased in nonsurvivors and strongly associated with mortality (adjusted OR 3.42, 95% CI 2.76-4.25, P < 0.001). The association between hyponatremia and mortality remained unchanged when adding copeptin levels to the regression model (fully adjusted OR 1.53, 95% CI 1.16-2.00, P = 0.002).

CONCLUSION

This prospective study including medical patients upon emergency room admission found hyponatremia as well as an activation of the vasopressin system to be independently associated with mortality. This suggests that stress- and vasopressin-independent mechanisms are responsible for the association of low sodium levels with mortality.

Thiazide-Associated Hyponatremia, Report of the Hyponatremia Registry: An Observational Multicenter International Study

BACKGROUND

Hyponatremia is a frequent and potentially life-threatening adverse side effect of thiazide diuretics. This sub-analysis of the Hyponatremia Registry database focuses on current management practices of thiazide-associated hyponatremia (TAH) and compares differences between TAH and syndrome of inappropriate antidiuretic hormone secretion (SIADH).

METHODS

We analyzed 477 patients from 225 US and EU sites with euvolemic hyponatremia ([Na+] ≤130 mEq/L) who were receiving a thiazide diuretic. Of these, 118 met criteria for true thiazide-induced hyponatremia (TIH).

RESULTS

Thiazide was withdrawn immediately after hyponatremia was diagnosed only in 57% of TAH; in these patients, the median rate of [Na+] change (Δdaily[Na+]) was significantly higher than those with continued thiazide treatment (3.8 [interquartile range: 4.0] vs. 1.7 [3.8] mEq/L/day). The most frequently employed therapies were isotonic saline (29.6%), fluid restriction (19.9%), the combination of these two (8.2%), and hypertonic saline (5.2%). Hypertonic saline produced the greatest Δdaily[Na+] (8.0[6.4] mEq/L/day) followed by a combination of fluid restriction and normal saline (4.5 [3.8] mEq/L/day) and normal saline alone (3.6 [3.5] mEq/L/day). Fluid restriction was markedly less effective (2.7 [2.7] mEq/L/day). Overly rapid correction of hyponatremia occurred in 3.1% overall, but in up to 21.4% given hypertonic saline. Although there are highly significant differences in the biochemical profiles between TIH and SIADH, no predictive diagnostic test could be derived.

CONCLUSIONS

Despite its high incidence and potential risks, the management of TAH is often poor. Immediate withdrawal of the thiazide is crucial for treatment success. Hypertonic saline is most effective in correcting hyponatremia but associated with a high rate of overly rapid correction. We could not establish a diagnostic laboratory-based test to differentiate TIH from SIADH.

Electrolyte and Acid-Base Disorders in Chronic Kidney Disease and End-Stage Kidney Failure

The kidneys play a pivotal role in the regulation of electrolyte and acid-base balance. With progressive loss of kidney function, derangements in electrolytes and acid-base inevitably occur and contribute to poor patient outcomes. As chronic kidney disease (CKD) has become a worldwide epidemic, medical providers are increasingly confronted with such problems. Adequate diagnosis and treatment will minimize complications and can potentially be lifesaving. In this review, we discuss the current understanding of the disease process, clinical presentation, diagnosis and treatment strategies, integrating up-to-date knowledge in the field. Although electrolyte and acid-base derangements are significant causes of morbidity and mortality in CKD and end-stage renal disease patients, they can be effectively managed through a timely institution of combined preventive measures and pharmacological therapy. Exciting advances and several upcoming outcome trials will provide further information to guide treatment and improve patient outcomes.

Cost-effectiveness of tolvaptan for the treatment of hyponatraemia secondary to syndrome of inappropriate antidiuretic hormone secretion in Sweden

BACKGROUND

Tolvaptan is the only vasopressin V2 receptor antagonist licensed by the European Medicines Agency for the treatment of hyponatraemia (HN) secondary to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). We have investigated the cost-effectiveness of tolvaptan versus no active treatment (NAT) in adult patients within the licensed indication who have either failed to respond to fluid restriction or for whom the use of fluid restriction is not suitable, from the societal perspective in Sweden.

METHODS

A cost-utility analysis, considering a 'general SIADH' population and two subpopulations of patients (small-cell lung cancer [SCLC] and pneumonia) to broadly represent the complex clinical pathway of SIADH, was performed. A discrete event simulation was developed to model the progression of individuals through inpatient admissions over a 30-day time horizon (180 days for the SCLC cohort). Clinical data were derived from tolvaptan trials and observational data sources. All costs are given in Swedish kronor (SEK).

RESULTS

In the 'general SIADH' population, tolvaptan was associated with reduced costs (SEK 5,779 per patient [€624]) and increased quality-adjusted life-years (QALYs) (0.0019) compared with NAT and was therefore the dominant treatment strategy. Tolvaptan was also associated with reduced costs and increased QALYs in the SCLC and pneumonia subpopulations. The most influential variables in our analysis were reduction in hospital length of stay, duration of treatment and long term treatment with tolvaptan in SCLC patients.

CONCLUSIONS

Tolvaptan represents a cost-effective treatment option in Sweden for hospitalised patients with HN secondary to SIADH who have either failed to respond to or are unsuitable for fluid restriction.

Hyponatremia in the general population. What does it mean?

Hyponatremia is a frequent problem in clinical practice and is known to be associated with a variety of serious adverse outcomes. Estimates from the US general population and several community-based cohorts indicate that hyponatremia is also relatively common in these settings, especially among seniors, individuals with underlying disease, and those taking a variety of prescription medications. Prevalence is greatly increased when persons with a "low normal" level of serum sodium are considered. Population-based studies have identified a U-shaped relationship between serum sodium and all-cause mortality, with the increased risk at the lower end of the distribution being seen in persons with a "low normal" level of serum sodium as well as those meeting the traditional definition of hyponatremia. The hyponatremia associated risk in epidemiologic studies is of lesser magnitude than in hospital-based studies but of great potential importance give the much larger number of persons with a low serum sodium in the general population. An important challenge for the research community is to determine whether low levels of serum sodium are a direct cause of increased risk. Population-based studies are likely to provide the best opportunity to resolve this question.

Clinical and Genetic Factors Associated With Thiazide-Induced Hyponatremia

Thiazide diuretics are associated with an increased risk of hyponatremia. The aim of this study was to investigate possible predictors of thiazide-induced hyponatremia.A total of 48 patients admitted to the ward or to the emergency department due to severe thiazide-induced hyponatremia (Na < 125 mmol/L) were enrolled in our study as the case group. Another 211 hypertensive patients with normal sodium levels after treatment with thiazide diuretics were selected as the control group. Twelve tag single nucleotide polymorphism markers were selected from the Potassium Channel, Inwardly Rectifying Subfamily J, Member 1 (KCNJ1) gene: rs1231254, rs2238009, rs1148058, rs675482, rs673614, rs12795437, rs2855800, rs2509585, rs3016774, rs881333, rs4529890, and rs7116606. Clinical and genetic parameters between patients with thiazide-induced hyponatremia and the control group were compared. Logistic regression was used to analyze data.The patients with thiazide-induced hyponatremia were older (P < 0.001), predominantly female (P = 0.008), had a lower mean body mass index (BMI) (P < 0.001), and more commonly used angiotensin II receptor antagonist (P < 0.001) and spironolactone (P = 0.007) compared with the control groups. Analysis with multivariate logistic regression revealed that age (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.08-1.19, P < 0.001), female gender (OR, 4.49; 95% CI, 1.54-13.11, P = 0.006), BMI (OR, 0.80; 95% CI, 0.69-0.93, P = 0.003), and KCNJ1 rs2509585 C/T or T/T polymorphisms (OR, 5.75; 95% CI, 1.25-26.45, P = 0.03) were independent predictors for thiazide-induced hyponatremia.Older female patients with lower BMIs and KCNJ1 rs2509585 C/T or T/T polymorphisms were more likely to develop thiazide-induced hyponatremia.

Inpatient hyponatraemia: adequacy of investigation and prevalence of endocrine causes

This study assessed the effect of endocrine input on the investigation of hyponatraemia and examined the prevalence of endocrine causes of hyponatraemia. This single-centre, retrospective study included 139 inpatients (median age, 74 years) with serum sodium (Na) levels ≤128 mmol/l during hospitalisation at a UK teaching hospital over a three-month period. In total, 61.9% of patients underwent assessment of volume status and 28.8% had paired serum and urine osmolality, and Na measured. In addition, 14.4% of patients received endocrine input; 80% of these patients underwent full work-up of hyponatraemia compared with 5% of patients not referred to endocrine services (p < 0.001; relative risk, 15.86; 95% confidence interval, 7.17-31.06). The prevalence of adrenal insufficiency was 0.7%, but basal serum cortisol levels were not measured in around two-thirds of patients. Despite 26.7% of patients having abnormal thyroid function tests, no patient was diagnosed with severe hypothyroidism. More widespread provision of expert input should be considered.

Management of hyponatremia in various clinical situations

OPINION STATEMENT

Hyponatremia is the most common electrolyte abnormality in both inpatient and outpatient settings. The condition primarily results from the combination of impaired free water excretion due to elevated vasopressin levels in conjunction with a source of free water intake. Recent studies have revealed that even mild and asymptomatic hyponatremia is associated with deleterious consequences. It is an independent risk factor for mortality and is also associated with increased length of hospitalization and hospital costs. Even mild chronic hyponatremia can result in subtle neurologic impairment and bone demineralization, leading to falls and associated bone fractures in the elderly. Hyponatremia can be a difficult condition to treat, with varying therapeutic strategies based on the etiology, severity, duration, and extent of neurologic symptoms. The ideal magnitude of correction is also controversial, as both inadequate therapy and overly aggressive therapy can result in neurologic injury. Formulas that have been devised to aid in the treatment of hyponatremia can be inaccurate in that they fail to adequately account for the renal response to therapy. Hyponatremic encephalopathy is the most serious complication of hyponatremia, and can result in permanent neurologic impairment or death if left untreated. Individuals most at risk for developing hyponatremic encephalopathy are postmenarchal women, children under 16 years of age, patients with central nervous system disease or hypoxemia, and patients in the postoperative setting. The preferred therapy for hyponatremic encephalopathy is a 100-ml bolus of 3 % sodium chloride (513 mEq/L) administered in repeated doses until symptoms reverse, with the goal of increasing the serum sodium 5-6 mEq/L. Vasopressin (V2) antagonists (vaptans) are not appropriate for the management of acute hyponatremic encephalopathy, as the onset of action is not sufficiently rapid and the increase in sodium is not predictable. Vaptans are primarily indicated for the treatment of asymptomatic hyponatremia due to SIAD that is refractory to conventional measures.