Burden of sodium abnormalities in patients hospitalized for heart failure

Prognostic impact of abnormal sodium burden in heart failure patients with preserved ejection fraction

BACKGROUND

Sodium abnormality is common in patients with heart failure (HF) and is associated with adverse clinical outcomes. The aim of this study is to determine the impact of abnormal sodium burden on long-term mortality and hospitalization in HF with preserved ejection fraction (HFpEF).

METHODS

We analysed participants from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial with available baseline and follow-up data (n = 1717). Abnormal sodium burden was defined as the proportion of days with abnormal sodium plasma levels (either <135 mmol/L or > 145 mmol/L). To determine the independent prognostic impact of abnormal sodium burden on the long-term clinical adverse outcomes (The primary outcome was any cause death, the secondary outcomes include cardiovascular disease death, HF hospitalization, any cause hospitalization and the primary endpoint of the original study), a multivariable Cox proportional hazard model and time-updated Cox regression model were performed.

RESULTS

Abnormal sodium burden occurred in 717 patients (41.76%). A high abnormal sodium burden was associated with 1.47 (95% CI, 1.15-1.89) higher risk with any cause mortality, 1.51 (95% CI, 1.08-2.09) higher risk with CVD death and 1.31 (95% CI, 1.02-1.69) higher risk with HF hospitalization when compared with no burden group. When sodium level changes over time were accounted for in time-updated models, abnormal sodium level was still associated with poor clinical outcomes. Diuretic and spironolactone usage did not show a statistical interaction effect on the prognostic significance.

CONCLUSIONS

In HFpEF patients, abnormal sodium burden was an independent predictor long-term any-cause mortality and HF hospitalization.

Relationship between serum sodium levels and all-cause mortality in congestive heart failure patients: A retrospective cohort study based on the Mimic-III database.. [DOI: 10.21203/rs.3.rs-1919991/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

BACKGROUND: The relationship between serum sodium levels and mortality in congestive heart failure (CHF) patients has not been well studied previously. Serum sodium levels are linked to an increased risk of all-cause death in CHF patients over the short, medium, and long term. Serum sodium levels are strongly linked to an increased risk of death from congestive heart failure and could be a new risk factor for cardiovascular disease. The goal of this study is to look into the relationship between serum sodium levels and all-cause mortality in people with CHF after controlling for other factors.METHODS: The publicly accessible Mimic III database was the source of data for our study. We use the ICU Admission Scoring System to collect demographic data, laboratory findings, comorbidities, vital signs, and scoring information for each patient. Cox proportional risk analysis, smooth curve fitting, and the Kaplan-Meier survival curve were used to assess the relationship between baseline sodium levels and all-cause mortality in CHF patients.RESULTS: The segmentation regression model discovered a turning point value of serum sodium levels (137.5mmol/L) between serum sodium levels and all-cause mortality. According to the results of the fully adjusted Cox proportional hazard model, lower serum sodium levels (<137.5mmol/L) were associated with an increased risk of 30-day, 90-day, 365-day, and 4-year all-cause deaths. The HRs and 95th confidence intervals were 0.96 (0.94, 0.99) , 0.96 (0.94, 0.99), 0.96 (0.94, 0.98) , and 0.96 (0.95, 0.98), respectively; The higher Serum sodium levels(≥137.5mmol/L) were related to associate multiplied risk of 30-day, 90-day, 365-day, and 4-year all-cause deaths; the HRs and 95th confidence intervals were 1.02 (1.00, 1.05), 1.02 (1.00, 1.04), 1.02 (1.00, 1.03) , and 1.02 (1.00, 1.03), respectively.CONCLUSION: Serum sodium levels were u-shaped about all-cause mortality. In individuals with CHF, serum sodium levels are linked to an elevated risk of short-, medium-, and long-term all-cause mortality.

Relationship between serum sodium levels and all-cause mortality in congestive heart failure patients: A retrospective cohort study based on the Mimic-III database

BACKGROUND

The relationship between serum sodium levels and mortality in congestive heart failure (CHF) patients has not been well-studied previously. The non-linear correlation between serum sodium levels and mortality in patients with heart failure is currently controversial, and the relationship between different serum sodium levels and mortality is disputed. The goal of this study is to look into the relationship between serum sodium levels and all-cause mortality in people with CHF after controlling for other factors.

METHODS

The publicly accessible Mimic III database was the source of data for our study. We use the ICU Admission Scoring System to collect demographic data, laboratory findings, comorbidities, vital signs, and scoring information for each patient. Cox proportional risk analysis, smooth curve fitting, and the Kaplan-Meier survival curve were used to assess the relationship between baseline sodium levels and all-cause mortality in CHF patients.

RESULTS

The segmentation regression model discovered a turning point value of serum sodium levels (137.5 mmol/L) between serum sodium levels and all-cause mortality. According to the results of the fully adjusted Cox proportional hazard model, lower serum sodium levels (<137.5 mmol/L) were associated with an increased risk of 30, 90, 365-day, and 4-year all-cause deaths. The HRs and 95th confidence intervals were 0.96 (0.94, 0.99), 0.96 (0.94, 0.99), 0.96 (0.94, 0.98), and 0.96 (0.95, 0.98), respectively; the higher serum sodium levels (≥137.5 mmol/L) were related to an associated multiplied risk of 30, 90, 365-day, and 4-year all-cause deaths; the HRs and 95th confidence intervals were 1.02 (1.00, 1.05), 1.02 (1.00, 1.04), 1.02 (1.00, 1.03), and 1.02 (1.00, 1.03), respectively.

CONCLUSION

Serum sodium levels were u-shaped about all-cause mortality. In individuals with CHF, serum sodium levels are linked to an elevated risk of short-, medium-, and long-term all-cause mortality.

Prognostic impact of hyponatraemia and hypernatraemia at admission and discharge in heart failure patients with preserved, mid-range and reduced ejection fraction

BACKGROUND

Hyponatraemia is common in patients with acute heart failure (HF).

AIMS

To determine the impact of sodium disturbances on mortality and readmissions in HF with reduced left ventricular ejection fraction (HFrEF), preserved ejection fraction (HFpEF) and mid-range ejection fraction (HFmrEF).

METHODS

This study was a prospective multicentre consecutive registry in 20 hospitals, including patients admitted due to acute HF in cardiology departments. Sodium <135 mmol/L was considered hyponatraemia, >145 mmol/L hypernatraemia and 135-145 mmol/L normal.

RESULTS

A total of 1309 patients was included. Mean age was 72.0 ± 11.9 years, and 810 (61.9%) were male. Mean serum sodium level was 138.6 ± 4.7 mmol/L at hospital admission and 138.1 ± 4.1 mmol/L at discharge. The evolution of sodium levels was: normal-at-admission/normal-at-discharge 941 (71.9%), abnormal-at-admission/normal-at-discharge 127 (9.7%), normal-at-admission/abnormal-at-discharge 155 (11.8%) and abnormal-at-admission/abnormal-at-discharge 86 (6.6%). Hyponatraemia at discharge was more common in HFrEF (109 (20.7%)) than in HFpEF (79 (13.9%)) and HFmrEF (27 (12%)), P = 0.003. The prevalence of hypernatraemia at discharge was similar in the three groups: HFrEF (10 (1.9%)), HFpEF (12 (2.1%)) and HFmrEF (4 (1.9%)), P = 0.96. In multivariate analysis, abnormal sodium concentrations at hospital admission (hazard ratio (HR) 1.42, 95% confidence interval (CI) 1.15-1.76, P = 0.001) and discharge (HR 1.33, 95% CI 1.08-1.64, P = 0.007) were both independently associated with increased mortality and readmissions at 12 months.

CONCLUSIONS

Hyponatraemia and hypernatraemia at admission and discharge predict a poor outcome in patients with acute HF regardless of left ventricular ejection fraction. Hyponatraemia at discharge is more frequent in HFrEF than in the other groups.

Prognostic Significance of Hyponatremia in ST-elevation Myocardial Infarction/Heart Failure Patients

ST-elevation myocardial infarction (STEMI) and heart failure (HF) are common, big-budget, debilitating and expanding diseases. Cardiovascular diseases, especially STEMI and heart failure have been known to cause 17.3 million deaths worldwide annually. Hyponatremia, delineated as a serum sodium (sNa) concentration <135 mmol/l, is a frequently seen electrolyte disturbance in practice and the prevalence, clinical impact; the prognostic factor of low SNa in STEMI/heart failure patients vary widely. The aim of this review is to assess its existence and comparing survival difference between hypo and normonatremic patients. A comprehensive review of the published articles was conducted using database PubMed. We found a total of over 1400 articles. The inclusion criteria used for this review were age >65 years, published within the last 10 years, written in English, performed on human subjects and of studies such as reviews and randomized controlled trials (RCTs), especially for heart failure MeSH words. By applying this inclusion criterion, we found out 40 relevant articles which included 26 cohort studies, four clinical trials, four review articles, and six RCTs. In the analysis of 7,06,899 patients with STEMI/heart failure, hyponatremia was significantly linked to causing all-cause mortality, both short and long term (hazard ratio [HR] as continuous variable: 1.06; 95% confidence interval [CI]: 1.01-1.11; P = 0.026; HR as categorical variable: 1.71; 95% CI: 1.06-2.75; P = 0.028). The rates of rehospitalization were also higher (odds ratio, 1.68; 95% confidence interval, 1.32-2.14) along with prolonged hospital stays as well as a greater cost burden as compared to patients with normal serum sodium. It was existent not only in patients with reduced ejection fraction (HFrEF) but also in subjects with preserved ejection fraction (HFpEF) (HR 1.40, 95% CI 1.12 to 1.75, P = 0.004). Rise of first follow-up and discharge sodium does seem to have positive linkage on survival as well (hazard ratio [HR] 0.429, 95% CI 0.191-0.960, P = 0.04). Hyponatremia is the most frequently encountered electrolyte abnormality in clinical practice and has a poor prognosis in both STEMI and heart failure patients. It exacerbates both short and long term mortality, rehospitalization rates, as well as the average length of stay in the hospital. Although it is still a mystery whether hyponatremia is just a marker of iller patients or the core of poor prognosis in patients with STEMI and HF, one thing is certain: timely recognition of patients at risk for developing hyponatremia could help to commence early treatment.

Electrolyte imbalances in an unselected population in an emergency department: A retrospective cohort study

BACKGROUND

Although electrolyte imbalances (EIs) are common in the emergency department (ED), few studies have examined the occurrence of such conditions in an unselected population.

OBJECTIVES

To investigate the frequency of EI among adult patients who present to the ED, with regards to type and severity, and the association with age and sex of the patient, hospital length of stay (LOS), readmission, and mortality.

METHODS

A retrospective cohort study. All patients ≥18 years referred for any reason to the ED between January 1, 2010, and December 31, 2015, who had measured blood electrolytes were included. In total, 62 991 visits involving 31 966 patients were registered.

RESULTS

EIs were mostly mild, and the most common EI was hyponatremia (glucose-corrected) (24.6%). Patients with increasing severity of EI had longer LOS compared with patients with normal electrolyte measurements. Among all admitted patients, there were 12928 (20.5%) readmissions within 30 days from discharge during the study period. Hyponatremia (glucose-corrected) was associated with readmission, with an adjusted odds ratio (OR) of 1.25 (95% CI, 1.18-1.32). Hypomagnesemia and hypocalcemia (albumin-corrected) were also associated with readmission, with ORs of 1.25 (95% CI, 1.07-1.45) and 1.22 (95% CI, 1.02-1.46), respectively. Dysnatremia, dyskalemia, hypercalcemia, hypermagnesemia, and hyperphosphatemia were associated with increased in-hospital mortality, whereas all EIs except hypophosphatemia were associated with increased 30-day and 1-year mortality.

CONCLUSIONS

EIs were common and increasing severity of EIs was associated with longer LOS and increased in-hospital, 30-days and 1-year mortality. EI monitoring is crucial for newly admitted patients, and up-to-date training in EI diagnosis and treatment is essential for ED physicians.

Economic impact of tolvaptan treatment vs. fluid restriction based on real-world data among hospitalized patients with heart failure and hyponatremia

OBJECTIVES

To estimate the cost difference associated with tolvaptan treatment vs. fluid restriction (FR) among hospitalized patients with heart failure (HF) and hyponatremia (HN) based on a real-world registry of HN patients.

METHODS

An Excel-based economic model was developed to evaluate the cost impact of tolvaptan treatment vs. FR. Model input for hospital length of stay (LOS) was based on published data from the Hyponatremia Registry (HNR). Based on HNR data, tolvaptan-treated patients had a 2-day (median) shorter LOS compared to FR. Real-world effectiveness of tolvaptan treatment from the HNR was applied to a national sample of inpatients visits from the Premier Hospital database to estimate the potential LOS-related cost difference between tolvaptan treatment and FR. A one-way sensitivity and multivariable Monte Carlo sensitivity analysis were conducted.

RESULTS

Economic modeling results of the base-case analysis indicated that among hospitalized patients with HF, the hospital cost per admission, not including HN drug cost, was $3453 lower among patients treated with tolvaptan vs. FR, due to the shorter LOS associated with tolvaptan treatment. At wholesale acquisition cost of $362 per day and an average treatment duration of 3.2 days, the pharmacy cost of tolvaptan treatment per admission was estimated at $1157. Thus, after factoring the decrease in hospital medical costs and increase in pharmacy costs associated with tolvaptan treatment, results indicated a cost-offset opportunity of -$2296 per admission for patients treated with tolvaptan versus FR. Results of the sensitivity analyses were consistent with the base-case analysis.

LIMITATIONS

The model derives inputs from real-world observational data. No causal relationship can be inferred from this analysis.

CONCLUSIONS

Based on this economic analysis, tolvaptan treatment vs. FR among hospitalized patients with HF and HN may be associated with lower hospital-related costs, which offset the increase in pharmacy costs associated with tolvaptan treatment.

Hospital-Associated Hypernatremia Spectrum and Clinical Outcomes in an Unselected Cohort

BACKGROUND

Although hypernatremia is associated with adverse outcomes, most studies examined selected populations.

METHODS

Discharge data of 19,072 unselected hospitalized adults were analyzed. The crude relationship between serum sodium [Na⁺] and mortality defined hypernatremia as serum [Na⁺] >142 mEq/L. Patients with community-acquired hypernatremia or hospital-acquired hypernatremia were compared with normonatremic patients (admission [Na⁺] 138-142 mEq/L) regarding in-hospital mortality, length of stay, and discharge disposition. Patients with community-acquired hypernatremia whose hypernatremia worsened during hospitalization were compared with those without aggravation.

RESULTS

Community-acquired hypernatremia occurred in 21% of hospitalized patients and was associated with an adjusted odds ratio (OR) of 1.67 (95% confidence interval [CI], 1.38-2.01) for in-hospital mortality and 1.44 (95% CI, 1.32-1.56) for discharge to a short-/long-term care facility and an adjusted 10% (95% CI, 7-13) increase in length of stay. Hospital-acquired hypernatremia developed in 25.9% of hospitalized patients and was associated with an adjusted OR of 3.17 (95% CI, 2.45-4.09) for in-hospital mortality and 1.45 (95% CI, 1.32-1.59) for discharge to a facility, and an adjusted 49% (95% CI, 44-53) increase in length of stay. Hospital-aggravated hypernatremia developed in 11.7% of patients with community-acquired hypernatremia and was associated with greater risk of in-hospital mortality (adjusted OR, 1.84; 95% CI, 1.32-2.56) and discharge to a facility (adjusted OR, 2.14; 95% CI, 1.71-2.69), and an adjusted 16% (95% CI, 7-27) increase in length of stay.

CONCLUSIONS

The hypernatremia spectrum in unselected hospitalized patients is independently associated with increased in-hospital mortality and heightened resource consumption.

An economic analysis of tolvaptan compared with fluid restriction among hospitalized patients with hyponatremia

OBJECTIVE

The vasopressin-receptor antagonist tolvaptan is used for the treatment of hyponatremia (HN) in hospitalized patients with congestive heart failure (CHF) or syndrome of inappropriate antidiuretic hormone secretion (SIADH). The objective of this economic modeling study was to assess the potential cost and health outcomes associated with tolvaptan in comparison with fluid restriction (FR).

METHODS

A decision-analytic model was developed to estimate potential cost and health outcomes associated with tolvaptan compared with FR among hospitalized CHF and SIADH patients with severe HN (serum sodium [SS] levels < 125 mEq/L). The model, which was populated with data from the published literature, assumes that response to treatment influences hospital length of stay, probability of an intensive care unit (ICU) admission, and probability of a 30-day all-cause hospital readmission. One-way and probabilistic sensitivity analyses (PSAs) assessed the influence of parameter uncertainty on model results.

RESULTS

Model results suggest that, among hospitalized CHF patients with severe HN, the use of tolvaptan compared with FR may lead to reductions of 7.2% and 4.6% in ICU admissions and 30-day readmissions, respectively. Compared with FR, tolvaptan may result in total cost-savings of $156 per hospitalized CHF patient. Among hospitalized SIADH patients with severe HN, the model suggested reductions of 14.6% and 5.1% in ICU admissions and 30-day readmissions, respectively. Compared with FR, tolvaptan may result in total cost-savings of $135 per hospitalized SIADH patient. PSAs found that the probabilities of net cost-savings from the use of tolvaptan compared with FR were 64% and 59% among patients with severe HN with CHF and SIADH, respectively.

CONCLUSIONS

Decision-analytic modeling based on published data for hospitalized CHF and SIADH patients with severe HN, indicates that tolvaptan compared with FR has the potential to improve health outcomes and produce cost-savings that more than offset the cost of tolvaptan.

Community-acquired hyperkalemia in elderly patients: risk factors and clinical outcomes

BACKGROUND

Although the risk and related factors of hyperkalemia developed in the hospital are known in elderly, risk and related factors of community-acquired hyperkalemia (CAH) in this population are not well known. This study was performed to investigate the risk of CAH in elderly and evaluate the related factors and clinical outcomes. Study design, setting and participants, intervention: Patients (aged ≥65 years) with hyperkalemia were screened. Group 1 (young-old); 65-74 years/old, Group 2 (middle-old); 75-84 years/old, Group 3 (oldest-old); ≥85 years/old, and Group 4 (control group); ≥65 years/old (normal serum potassium levels). The relation between CAH and hospital expenses (HE), the number of comorbid diseases (NCD), and all-cause of mortality rates (MR) were evaluated. We also investigated whether drugs, sex, and NCD are risk factors for the development of CAH.

RESULTS

There was a positive correlation between serum potassium levels and length of hospital stay, MR, HE, and NCD (p < 0.001). Risk factors for CAH were the use of non-steroidal-anti inflammatory drugs (NSAIDs) (Odds Ratio [OR]: 2.679), spironolactone (OR: 2.530), and angiotensin converting enzyme inhibitors (ACEI) (OR: 2.242), angiotensin receptor blockers (ARB) (OR: 2.679), ≥2 comorbid diseases (OR: 2.221), female gender (OR: 2.112), and renal injury (OR: 5.55). CAH risk was found to be increased 30.03 times when any of ACEI, ARB, NSAIDs, or spironolactone is given to a patient with a renal injury.

CONCLUSION

Use of NSAIDs, ACEI, ARB, spironolactone and increased NCD are all independent risk factors for CAH in the elderly, especially in patients with kidney diseases.

Relation between serum sodium levels and clinical outcomes in Turkish patients hospitalized for heart failure: a multi-center retrospective observational study

Objective:

The purpose of the study was to analyze the prevalence of hyponatremia and related 1-year outcomes of patients hospitalized for decompensated heart failure with reduced ejection fraction (HFrEF) in Turkish patients.

Methods:

A total of 500 hospitalized patients with HFrEF were consecutively included in a retrospective study at 19 participating hospitals. Patients were categorized according to their serum sodium levels (sNa) on admission day as normonatremic (135–145 mEq/L) and hyponatremic (<135 mEq/L). One-year all-cause mortality, re-hospitalization rates, and the impact of the changes in sNa at the time of discharge to clinical outcomes were examined.

Results:

Hyponatremia was observed in 29% of patients. Patients with hyponatremia had lower blood pressures, creatinine clearance, and left ventricular ejection fraction and higher serum creatinine and BUN levels on admission compared with those with normonatremia. Hyponatremia was associated with higher 1-year all-cause mortality (14% vs. 2.6%, p<0.001) and re-hospitalization rates (46.9% vs. 33.7%, p=0.005). After adjustment for covariates, hyponatremia was independently associated with 1-year all-cause mortality (adjusted HR, 4.762; 95% CI, 1.941–11.764; p=0.001). At discharge, only 50.8% of hyponatremic patients were corrected to normonatremia (≥135 mEq/L). Those with persistent hyponatremia had the highest all-cause mortality (p<0.001).

Conclusion:

In this study, it is demonstrated that hyponatremia is relatively common and is associated with increased 1-year all-cause mortality and re-hospitalization rates among Turkish patients hospitalized with HFrEF. Approximately 50% of the patients with initial low sNa had persistent hyponatremia at discharge, and these patients had the worst clinical outcomes.

The Economic Burden of Hyponatremia: Systematic Review and Meta-Analysis

BACKGROUND

Hyponatremia is the most common electrolyte abnormality observed in clinical practice. Several studies have demonstrated that hyponatremia is associated with an increased length of hospital stay and of hospital resource utilization. To clarify the impact of hyponatremia on the length of hospitalization and costs, we performed a meta-analysis based on published studies that compared hospital length of stay and cost between patients with and without hyponatremia.

METHODS

An extensive Medline, Embase, and Cochrane search was performed to retrieve all studies published up to April 1, 2015 using the following words: "hyponatremia" or "hyponatraemia" AND "hospitalization" or "hospitalisation." A meta-analysis was performed including all studies comparing duration of hospitalization and hospital readmission rate in subjects with and without hyponatremia.

RESULTS

Of 444 retrieved articles, 46 studies satisfied the inclusion criteria, encompassing a total of 3,940,042 patients; among these, 757,763 (19.2%) were hyponatremic. Across all studies, hyponatremia was associated with a significantly longer duration of hospitalization (3.30 [2.90-3.71; 95% CIs] mean days; P < .000). Similar results were obtained when patients with associated morbidities were analyzed separately. Furthermore, hyponatremic patients had a higher risk of readmission after the first hospitalization (odds ratio 1.32 [1.18-1.48; 95% CIs]; P < .000). A meta-regression analysis showed that the hyponatremia-related length of hospital stay was higher in males (Slope = 0.09 [0.05-0.12; 95% CIs]; P = .000 and Intercept = -1.36 [-3.03-0.32; 95% CIs]; P = .11) and in elderly patients (Slope = 0.002 [0.001-0.003; 95% CIs]; P < .000 and Intercept = 0.89 [0.83-0.97; 95% CIs]; P < .001). A negative association between serum [Na(+)] cutoff and duration of hospitalization was detected. No association between duration of hospitalization, serum [Na(+)], and associated morbidities was observed. Finally, when only US studies (n = 8) were considered, hyponatremia was associated with up to around $3000 higher hospital costs/patient when compared with the cost of normonatremic subjects.

CONCLUSIONS

This meta-analysis confirms that hyponatremia is associated with a prolonged hospital length of stay and higher risk of readmission. These observations suggest that hyponatremia may represent one important determinant of the hospitalization costs.

Hyponatremia in patients hospitalized with heart failure: a condition often overlooked in low-income settings

Background

Hyponatremia is a common electrolyte abnormality in patients with heart failure (HF). It is independently associated with increased short-term and long-term morbidity and mortality. The main objective of this study was to assess patterns of hyponatremia and its association with discharge outcomes in patients with HF admitted to a teaching hospital in Ethiopia.

Patients and methods

This is a descriptive, prospective, hospital-based cohort study of patients with HF admitted to Jimma University Hospital, Ethiopia, between November 1, 2013 and July 31, 2014. A structured questionnaire was used to collect information on sociodemographic characteristics, clinical profile at admission, and outcomes at discharge. Plasma sodium concentration was analyzed at admission for all patients. The relationship between hyponatremia at admission and in-hospital mortality, as well as length of hospital stay, was assessed using both bivariate analysis and multivariable logistic regressions. The level of statistical significance was set at P<0.05.

Results

Of 152 participants admitted with HF, 44 (28.9%) had hyponatremia, which is defined as serum sodium level <135 mmol/L. Patients on salt restriction, on chronic diuretic treatment (furosemide and spironolactone), and with impaired renal function at admission were found to be highly affected. Hyponatremia was found to be associated with increased in-hospital mortality (P=0.008) and longer hospital stay (16.6 vs 12 days, P<0.001). Patients with hyponatremia also had lower blood pressure and poor functional status at discharge.

Conclusion

This study demonstrates that hyponatremia is highly prevalent in patients hospitalized with HF and is associated with increased in-hospital mortality and longer hospital stay. Thus, great emphasis should be given to identify high-risk patients, and prevention and early detection of hyponatremia to prevent its deleterious effects. Large-scale national studies are also needed to complement our findings.

Comparison of salt with low-dose furosemide and carperitide for treating acute decompensated heart failure: a single-center retrospective cohort study

Hypertonic saline with furosemide has been proposed for a long time as an effective therapeutic option for the treatment of acute decompensated heart failure (ADHF). We previously reported the efficacy of continuous infusion of 1.7 % hypertonic saline plus low-dose furosemide in treatment for ADHF. Although this therapeutic strategy can be a useful option for effective decongestion in treatment for ADHF, there is no study that assesses the effect and safety of saline supplementation compared with standard therapy in Japan. The aim of this study was to investigate the efficacy, safety, and cost-effectiveness of 1.7 % hypertonic saline plus low-dose furosemide infusion compared with carperitide. We compared clinical outcomes, adverse events, and cost for patients receiving carperitide (carperitide group) with those for patients receiving 1.7 % hypertonic saline plus low-dose furosemide (salt group) during the initial hospitalization for ADHF. The cost analysis was performed on the basis of the previous report about cost-effectiveness of acute heart failure. A total of 175 ADHF patients received either carperitide (n = 111) or 1.7 % hypertonic saline plus low-dose furosemide infusion (n = 64) as initial treatment. There were no differences in length of hospital stay (27 ± 19 vs. 25 ± 16 day, p = 0.170) and infusion period (7.2 ± 6.1 vs. 8.4 ± 7.5 day, p = 0.474) between the two groups. The incidence of rehospitalization did not differ at 1 month (7.6 vs. 6.6 %, p = 1.000) and 1 year (36.8 vs. 37.7 %, p = 0.907) between the two groups. The Kaplan-Meier curves revealed no significant difference for 1 year all-cause mortality between the two groups (log-rank, p = 0.724). The single hospitalization cost was 95,314 yen lower and the yearly hospitalization cost 125,628 yen lower in the salt group compared with the carperitide group. Thus, intravenous 1.7 % hypertonic saline plus low-dose furosemide infusion is as effective as carperitide in terms of clinical outcome and is a cost-effective therapeutic strategy for the treatment of ADHF.

Dehydration in the Elderly: A Review Focused on Economic Burden

BACKGROUND

Dehydration is the most common fluid and electrolyte problem among elderly patients. It is reported to be widely prevalent and costly to individuals and to the health care system. The purpose of this review is to summarize the literature on the economic burden of dehydration in the elderly.

METHOD

A comprehensive search of several databases from database inception to November 2013, only in English language, was conducted. The databases included Pubmed and ISI Web of Science. The search terms «dehydration» / "hyponaremia" / "hypernatremia" AND «cost» AND «elderly» were used to search for comparative studies of the economic burden of dehydration. A total of 15 papers were identified.

RESULTS

Dehydration in the elderly is an independent factor of higher health care expenditures. It is directly associated with an increase in hospital mortality, as well as with an increase in the utilization of ICU, short and long term care facilities, readmission rates and hospital resources, especially among those with moderate to severe hyponatremia.

CONCLUSIONS

Dehydration represents a potential target for intervention to reduce healthcare expenditures and improve patients' quality of life.

Effect of the pretransplant serum sodium concentration on outcomes following liver transplantation

Hyponatremia is associated with an increased risk of mortality on the liver transplantation (LT) waiting list. Although the incorporation of the serum sodium (Na) level into the Model for End-Stage Liver Disease score may reduce wait-list mortality, concerns remain about a potential association between pre-LT hyponatremia and decreased post-LT survival. Furthermore, the relationship between pre-LT hypernatremia and post-LT survival remains unexplored. The purpose of this study was to investigate the impact of the entire spectrum of pre-LT serum Na levels on post-LT outcomes. We identified 19,537 patients from 2003 to 2010 for whom serum Na levels immediately before LT were available. The patients were divided into 3 groups [hyponatremic (Na ≤ 130 mEq/L), normonatremic (Na = 131-145 mEq/L), and hypernatremic (Na > 145 mEq/L)], and their post-LT outcomes were compared. There was no difference in in-hospital mortality or 90-day survival between patients with hyponatremia and patients with normonatremia. A fraction of the patients (2.4%) had hypernatremia, which was associated with increased in-hospital mortality (11.2% versus 4.2%, P < 0.001) and diminished 90-day survival (86.4% versus 94.0.%, P < 0.001). After adjustments for important clinical variables, the association of pre-LT hypernatremia with posttransplant mortality remained significant with a hazard ratio of 1.13 for each unit increase in the Na level > 145 mEq/L (P < 0.001). The duration of the hospitalization after LT was significantly longer for hypernatremic patients (P < 0.001). In conclusion, hyponatremia per se does not affect post-LT survival. Pre-LT hypernatremia is a highly significant risk factor for post-LT mortality.

Moderate hyponatremia is associated with increased risk of mortality: evidence from a meta-analysis

Background

Hyponatremia is the most common electrolyte disorder in clinical practice, and evidence to date indicates that severe hyponatremia is associated with increased morbidity and mortality. The aim of our study was to perform a meta-analysis that included the published studies that compared mortality rates in subjects with or without hyponatremia of any degree.

Methods and Findings

An extensive Medline, Embase and Cochrane search was performed to retrieve the studies published up to October 1^st 2012, using the following words: “hyponatremia” and “mortality”. Eighty-one studies satisfied inclusion criteria encompassing a total of 850222 patients, of whom 17.4% were hyponatremic. The identification of relevant abstracts, the selection of studies and the subsequent data extraction were performed independently by two of the authors, and conflicts resolved by a third investigator. Across all 81 studies, hyponatremia was significantly associated with an increased risk of overall mortality (RR = 2.60[2.31–2.93]). Hyponatremia was also associated with an increased risk of mortality in patients with myocardial infarction (RR = 2.83[2.23–3.58]), heart failure (RR = 2.47[2.09–2.92]), cirrhosis (RR = 3.34[1.91–5.83]), pulmonary infections (RR = 2.49[1.44–4.30]), mixed diseases (RR = 2.59[1.97–3.40]), and in hospitalized patients (RR = 2.48[2.09–2.95]). A mean difference of serum [Na⁺] of 4.8 mmol/L was found in subjects who died compared to survivors (130.1±5.6 vs 134.9±5.1 mmol/L). A meta-regression analysis showed that the hyponatremia-related risk of overall mortality was inversely correlated with serum [Na⁺]. This association was confirmed in a multiple regression model after adjusting for age, gender, and diabetes mellitus as an associated morbidity.

Conclusions

This meta-analysis shows for the first time that even a moderate serum [Na⁺] decrease is associated with an increased risk of mortality in commonly observed clinical conditions across large numbers of patients.

Lower serum potassium combined with lower sodium concentrations predict long-term mortality risk in hemodialysis patients

BACKGROUND

The purpose of this study was to evaluate the combined effect of different pre-hemodialysis (HD) serum sodium (S[Na]) and potassium (S[K]) concentrations on the long-term prognosis of HD patients.

METHODS

A cohort of 424 maintenance HD patients (age: 58 ± 13 years, male: 47%, diabetes: 39%) from a single center were divided into four groups based on both medians of S[Na] (138.4 mmol/L) and S[K] (4.4 mmol/L): Group 1: lower S[Na] & lower S[K]: n = 92; Group 2: lower S[Na] & higher S[K]: n =113; Group 3: higher S[Na] & lower S[K]: n =123; Group 4: higher S[Na] & higher S[K]: n =96. The median observation period was 21 months.

RESULT

By multivariate logistic regression analysis, Group 1 was characterized by hypoalbuminemia (OR = 0.37, 95%CI = 0.20-0.67), and lower normalized protein catabolism rate (nPCR) (OR = 0.37, 95% CI = 0.16-0.83). In contrast, Group 4 was characterized by higher nPCR (OR = 2.26, 95% CI = 1.05-4.86) and albumin level (OR = 2.26, 95% CI = 1.17-4.39). As compared to the reference (group 1), the HR for long-term mortality was significantly lower in Groups 3 (HR = 0.54, 95% CI = 0.34- 0.86) and 4 (HR = 0.49, 95% CI = 0.28-0.84). By multivariate Cox proportional analysis, Group 1 was an independent factor (HR = 1.74, 95% CI = 1.18-2.58) associated with long-term mortality.

CONCLUSION

HD patients combined with lower S[K] and lower S[Na] were characterized by hypoalbuminemia, lower nPCR and a high prevalence of co-morbidity. They were associated with long-term mortality risk. On the other hand, those patients with higher levels of S[Na] and S[K] tended to have better clinical outcomes.

Evaluation of patients with heart failure

Heart failure is one of the most prevalent cardiovascular diseases in the United States, and is associated with significant morbidity, mortality, and costs. Prompt diagnosis may help decrease mortality, hospital stay, and costs related to treatment. A complete heart failure evaluation comprises a comprehensive history and physical examination, echocardiogram, and diagnostic tools that provide information regarding the etiology of heart failure, related complications, and prognosis in order to prescribe appropriate therapy, monitor response to therapy, and transition expeditiously to advanced therapies when needed. Emerging technologies and biomarkers may provide better risk stratification and more accurate determination of cause and progression.

Clinical review: the use of vaptans in clinical endocrinology

CONTEXT

Hyponatremia is the most common electrolyte disorder encountered in clinical practice and represents a clinical, social, and economic burden. Conventional treatments of hyponatremia present some pitfalls, such as suboptimal efficacy, risk of overly rapid correction, and adverse effects. Vasopressin receptor antagonists, known as vaptans, represent a new and interesting class of drugs for the treatment of the euvolemic and hypervolemic forms of hyponatremia.

EVIDENCE ACQUISITION

This review is based on a PubMed search with the following terms: "vaptans," "vasopressin receptor antagonists," "tolvaptan," "conivaptan," "vasopressin receptor antagonists and SIADH," "vasopressin receptor antagonists and congestive heart failure," "vasopressin receptor antagonists and cirrhosis," and "vasopressin receptor antagonists and polycystic kidney disease."

EVIDENCE SYNTHESIS

Overall, the studies reported in this review indicate that vaptans effectively correct hyponatremia in euvolemic and hypervolemic patients. In the latter group, vaptans generally had favorable effects on fluid balance also. To date two vaptans, ie, conivaptan and tolvaptan, have been marketed in the United States for the treatment of euvolemic and hypervolemic hyponatremia, whereas tolvaptan has been marketed in Europe with the limitation of euvolemic hyponatremia. Although these drugs have a good safety profile, caution should be used, and treatment should be initiated in a hospital setting in order to closely monitor patients and avoid overly rapid correction or overcorrection.

CONCLUSIONS

Vaptans can be considered a new effective tool for the treatment of euvolemic and hypervolemic hyponatremia. Nevertheless, more comparative research of vaptans vs other therapies on clinical grounds is needed to more accurately assess the value of these drugs in the treatment of hyponatremia.

Healthcare resource burden associated with hyponatremia among patients hospitalized for heart failure in the US

OBJECTIVE

To evaluate the burden of hyponatremia in terms of hospital resource utilization, costs, and 30-day hospital readmission among patients hospitalized for heart failure (HF) in routine clinical practice.

METHODS

Hyponatremic (HN) patients (≥18 years of age) with HF discharged between January 2, 2007 and March 31, 2010 were selected from the Premier Hospital Database and matched to non-HN HF patients using exact and propensity score matching. Univariate and multivariate statistics were utilized to compare hospital resource utilization (total and intensive care unit (ICU)) and associated costs and 30-day hospital readmission among cohorts.

RESULTS

The study population included 51,710 subjects (HN = 25,855, non-HN = 25,855). In comparison to the non-HN cohort, length of stay (LOS) (7.7 ± 8.3 vs 6.3 ± 7.6 days, p < 0.001), hospitalization cost ($13,339 ± $19,273 vs $10,475 ± 15,157, p < 0.001), ICU LOS (4.9 ± 5.4 vs 4.2 ± 5.4 days, p < 0.001) and ICU cost ($7195 ± $9522 vs $5618 ± 10,919, p < 0.001) as well as rate of 30-day readmission (all cause: 25.3% vs 22.2%, p < 0.001; hyponatremia-related: 21.4% vs 5.0%, p < 0.001) were greater for the HN cohort. After adjustment, hyponatremia was associated with a 21.5% increase in hospital LOS, a 25.6% increase in hospital cost, a 13.7% increase in ICU LOS and a 24.6% increase in ICU cost. Additionally, hyponatremia was associated with increased risk of ICU admission (Odds Ratio (OR) = 1.58, [CI = 1.37, 1.84], p < 0.001) and 30-day hospital readmission (all cause: OR = 1.19, [CI = 1.14, 1.24], p < 0.001; hyponatremia-related: 5.10 [CI = 4.77, 5.46], p < 0.001).

LIMITATIONS

Laboratory data for serum sodium level are not available in the Premier database and the severity of hyponatremia could not be established, although several patient variables were controlled for in this study by exact and propensity score matching techniques.

CONCLUSIONS

Hyponatremia in HF patients is a predictor of increased hospital resource use and represents a potential target for intervention to reduce healthcare expenditures.

Hyponatremia-associated healthcare burden among US patients hospitalized for cirrhosis

INTRODUCTION

Hyponatremia is a frequent comorbid condition of patients hospitalized for cirrhosis and a predictor of disease severity and mortality. This study evaluated the healthcare burden of hyponatremia among patients hospitalized for cirrhosis in the real world.

METHODS

Hyponatremic (HN) patients (>-18 years of age) with cirrhosis were identified using the Premier Hospital Database (January 1, 2007 to March 31, 2010) and matched to non-HN patients with cirrhosis using a combination of exact patient characteristics and propensity score matching. Univariate and multivariate statistics were utilized to compare hospital resource utilization, cost, and 30-day hospital re-admission among patient cohorts.

RESULTS

The study population included 21,864 subjects (HN 10,932; non-HN 10,932). The hospital length of stay (LOS) (7.63 ± 7.4 vs. 5.89 ± 6.2 days; P < 0.001), hospital cost ($13,842 ± $20,702 vs. $11,140 ± $20,562; P < 0.001), intensive care unit (ICU) LOS (4.58 ± 4.7 vs. 3.59 ± 4.4 days; P < 0.001), and ICU cost ($7,038 ± $7,781 vs. $5,360 ± $7,557; P < 0.001) were greater for the HN cohort, as was the 30-day re-admission rate (all cause: 31.1% vs. 24.8%; P < 0.001; hyponatremia related: 25.1% vs. 11.0%; P < 0.001). Multivariate analysis showed that hyponatremia was associated with a 29.5% increase in hospital LOS, a 26.6% increase in overall hospital cost, a 23.2% increase in S. ICU LOS, and a 28.6% increase in ICU cost. Additionally, hyponatremia was associated with an increased risk of 30-day hospital re-admission (all cause: odds ratio [OR] 1.37; confidence interval [CI] 1.28-1.46; P < 0.001; hyponatremia related: OR 2.68; CI 2.48-2.90; P < 0.001).

CONCLUSION

Hyponatremia in patients with cirrhosis is a predictor of increased hospital resource use and 30-day hospital re-admission, and represents a potential target for intervention to reduce healthcare expenditures for patients hospitalized for cirrhosis.

Hyponatraemia: more than just a marker of disease severity?

Hyponatraemia--the most common serum electrolyte disorder--has also emerged as an important marker of the severity and prognosis of important diseases such as heart failure and cirrhosis. Acute hyponatraemia can cause severe encephalopathy, but the rapid correction of chronic hyponatraemia can also profoundly impair brain function and even cause death. With the expanding elderly population and the increased prevalence of hyponatraemia in this segment of society, prospective studies are needed to examine whether correcting hyponatraemia in the elderly will diminish cognitive impairment, improve balance and reduce the incidence of falls and fractures. Given that polypharmacy is also common in the elderly population, the various medications that may stimulate arginine vasopressin release and/or enhance the hormone's action to increase water absorption must also be taken into consideration. Whether hyponatraemia in a patient with cancer is merely a marker of poor prognosis or whether its presence may alter the patient's quality of life remains to be examined. In any case, hyponatraemia can no longer be considered as just a biochemical bystander in the ill patient. A systematic diagnostic approach is necessary to determine the specific aetiology of a patient's hyponatraemia. Therapy must then be dictated not only by recognized reversible causes such as advanced hypothyroidism, adrenal insufficiency, diuretics or other medicines, but also by whether the hyponatraemia occurred acutely or chronically. Information is emerging that the vast majority of cases of hyponatraemia are caused by the nonosmotic release of arginine vasopressin. Now that vasopressin V2-receptor blockers are available, a new era of clinical investigation is necessary to examine whether hyponatraemia is just a marker of severe disease or whether correction of hyponatraemia could improve a patient's quality of life. Such an approach must involve prospective randomized studies in different groups of patients with hyponatraemia, including those with advanced heart failure, those with cirrhosis, patients with cancer, and the elderly.

Evaluation of incremental healthcare resource burden and readmission rates associated with hospitalized hyponatremic patients in the US

BACKGROUND

Hyponatremia is a prevalent electrolyte disorder in hospitalized patients indicative of greater morbidity and mortality. A large-scale retrospective analysis was conducted to evaluate the incremental burden of hospitalized hyponatremic (HN) versus non-HN patients in terms of hospital resource utilization, costs, and hospital readmissions in the real-world setting.

METHODS

HN patients (≥18 years) were selected from the Premier Hospital Database between January 1, 2007 and March 31, 2010 and matched to a non-HN control cohort using propensity score matching. Bivariate and multivariate statistics were employed to evaluate the differences in healthcare resource utilization, costs, and hospital readmissions between patient cohorts.

RESULTS

Among the matched patient cohorts, length of stay (LOS) (8.8 ± 10.3 vs 7.7 ± 8.5 days, P < 0.001), hospital admission costs ($15,281 ± $24,054 vs $13,439 ± $22,198, P < 0.001), intensive care unit (ICU) LOS (5.5 ± 7.9 vs 4.9 ± 7.1 days, P < 0.001), and ICU costs ($8525 ± $13,342 vs $7597 ± $12,695, P < 0.001) were greater for the HN versus non-HN cohort, as were hospital readmission rates 30 days postdischarge. Multivariate regressions further demonstrated that hyponatremia was associated with an increase of 10.9% for LOS, 8.2% for total hospitalization costs, 10.2% for ICU LOS, and 8.9% for ICU costs. Additionally, after multivariate adjustment, hyponatremia was associated with a 15.0% increased chance for hospital readmission 30 days postdischarge (P < 0.0001).

CONCLUSIONS

Hyponatremia is an independent predictor of increased hospitalization LOS and cost, ICU admission and cost, and 30-day hospital readmission, and therefore represents a potential target for intervention to reduce healthcare expenditures for a large population of hospitalized hyponatremic patients.

Clinical challenge of hyponatremia in heart failure

Hyponatremia is a significant and independent predictor of outcomes including rehospitalization and mortality in patients with both acute decompensated heart failure (HF) and chronic HF. Even modest degrees of hyponatremia are associated with a poorer prognosis. Treatment options include fluid restriction and the vaptan class ("aquaretics") in select patients.

Evaluation of costs associated with tolvaptan-mediated length-of-stay reduction among heart failure patients with hyponatremia in the US, based on the EVEREST trial

BACKGROUND

The Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study with Tolvaptan (EVEREST) trial showed that tolvaptan use improved heart failure (HF) signs and symptoms without serious adverse events.

OBJECTIVE

To evaluate the potential cost savings associated with tolvaptan usage among hospitalized hyponatremic HF patients.

METHODS

The Healthcare Cost and Utilization Project (HCUP) 2008 Nationwide Inpatient Sample (NIS) database was used to estimate hospital cost and length of stay (LOS), for diagnosis-related group (DRG) hospitalizations of adult (age ≥18 years) HF patients with complications and comorbidities or major complications and comorbidities. EVEREST trial data for patients with hyponatremia were used to estimate tolvaptan-associated LOS reductions. A cost offset model was constructed to evaluate the impact of tolvaptan on hospital cost and LOS, with univariate and multivariate Monte Carlo sensitivity analyses.

RESULTS

Tolvaptan use among hyponatremic EVEREST trial HF patients was associated with shorter hospital LOS than placebo patients (9.72 vs 11.44 days, respectively); 688,336 hospitalizations for HF DRGs were identified from the HCUP NIS database, with a mean LOS of 5.4 days and mean total hospital costs of $8415. Using an inpatient tolvaptan treatment duration of 4 days with a wholesale acquisition cost of $250 per day, the cost offset model estimated a LOS reduction among HF hospitalizations of 0.81 days and an estimated total cost saving of $265 per admission. Univariate and multivariate sensitivity analysis demonstrated that cost reduction associated with tolvaptan usage is consistent among variations of model variables.

CONCLUSIONS

The estimated LOS reduction and cost savings projected by the cost offset model suggest a clinical and economic benefit to tolvaptan use in hyponatremic HF patients.

STUDY LIMITATIONS

The EVEREST trial data may not generalize well to the US population. Clinical trial patient profiles and relative LOS reductions may not be applicable to real-world patient populations.

Hyponatremia's Impact on Patients and Health Systems

Purpose

To define hyponatremia, discuss its incidence and epidemiology, and summarize the frequency and prognostic implications of hyponatremia in selected clinical conditions.

Summary

Hyponatremia is the most common electrolyte abnormality encountered in clinical practice. Hyponatremia is commonly defined as a serum sodium concentration of <136 mEq/L. There are 3 different types of hyponatremia: hypovolemia, euvolemia, and hypervolemia. Epidemiologic studies reveal that hyponatremia is a common problem in hospitalized patients whether it is present at admission or is hospital acquired. The disorder increases the risk of admission to the intensive care unit, hospital length of stay, and morbidity and mortality. Hyponatremia appears to be a marker for severe underlying disease with a poor prognosis. Congestive heart failure, pneumonia, cirrhosis, and neurologic disease are among the serious clinical conditions known to be associated with hyponatremia. Chronic hyponatremia presents its own set of challenges; even in mild disease that is often asymptomatic, patients are at heightened risk for falls, gait disturbances, attention deficits, and fracture.

Conclusion

Hyponatremia is the most common electrolyte disorder encountered in clinical practice and is associated with significant morbidity and mortality, especially at lower serum sodium concentrations. The disorder has a substantial impact on hospital length of stay with a direct impact on health care costs. Further, as this discussion illustrates, hyponatremia represents a significant clinical burden in all forms – mild, moderate, and severe – with subsequent clinical consequences.

Cost Issues in Hyponatremia

Purpose

To describe the morbidity and mortality associated with hyponatremia and its impact on health care costs and outcomes in the United States, describe the role of pharmacists in the overall management of hyponatremia, and identify and address cost and resource allocation issues.

Summary

Hyponatremia places a significant burden on overall hospital and health care costs. Underrecognition of the disorder and inappropriate hospital management can lead to worse outcomes, impacting length of stay (LOS), need for intensive care unit (ICU) admission, and clinical outcomes. Risk of mortality rises with increasing severity of hyponatremia, but even mild hyponatremia is associated with increased in-hospital mortality. The association with mortality is particularly robust in patients admitted to the hospital with cardiovascular disease and metastatic cancer. For patients admitted to the ICU, severe hyponatremia is a predictor of mortality. Elderly patients with admission hyponatremia face an especially poor prognosis. Resolving hyponatremia during hospitalization decreases the risk of mortality, suggesting that improved identification and aggressive monitoring may lead to more appropriate treatment. Pharmacoeconomic data can be utilized to support clinical decision-making in the management of hyponatremia by evaluating drug therapy and by monitoring hyponatremia development and therapeutic outcomes.

Conclusion:

Prompt recognition and optimal management of hyponatremia in hospitalized patients may reduce mortality and symptom severity, allow for less intensive care, decrease LOS and associated costs, and improve treatment of underlying comorbid conditions and quality of life. Pharmacists have a key role in optimizing the management of hyponatremia.

Hyponatremia in hospitalized patients: the potential role of tolvaptan

Hyponatremia (typically defined as serum sodium level < 135 mEq/L) is a common electrolyte abnormality among hospitalized patients. Whether present at admission or acquired during hospitalization, hyponatremia is associated with higher mortality and longer hospital stays. Failure to adequately investigate and treat hyponatremia may also be associated with adverse outcomes. The presence and severity of clinical symptoms largely depend on the rate and extent of the decline in serum sodium; rapid or large decreases may cause serious neurologic complications. The approach to treatment depends on the presence and severity of symptoms, the timing of their onset, the underlying etiology, and the patient's volume status. Patients with euvolemic or hypervolemic hyponatremia usually have inappropriately elevated levels of arginine vasopressin, which stimulates water reabsorption even in the presence of low serum osmolality. Tolvaptan is an orally active, selective V2-receptor antagonist that blocks the effects of arginine vasopressin in the renal collecting duct to promote aquaresis without increasing sodium or potassium excretion; as a result, it increases serum sodium in a controlled manner. Tolvaptan offers a mechanism-based treatment option for patients with euvolemic or hypervolemic hyponatremia who have serum sodium levels < 125 mEq/L or persistent symptoms resistant to fluid restriction.