Investigation and management of severe hyponatraemia in a hospital setting

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.

Inappropriate therapy of euvolemic hyponatremia, the most frequent type of hyponatremia in SARS-CoV-2 infection, is associated with increased mortality in COVID-19 patients

Introduction

Admission hyponatremia, frequent in patients hospitalized for COVID-19, has been associated with increased mortality. However, although euvolemic hyponatremia secondary to the Syndrome of Inappropriate Antidiuresis (SIAD) is the single most common cause of hyponatremia in community-acquired pneumonia (CAP), a thorough and rigorous assessment of the volemia of hyponatremic COVID-19 subjects has yet to be described. We sought to identify factors contributing to mortality and hospital length-of-stay (LOS) in hospitalized COVID-19 patients admitted with hyponatremia, taking volemia into account.

Method

Retrospective study of 247 patients admitted with COVID-19 to a tertiary hospital in Madrid, Spain from March 1st through March 30th, 2020, with a glycemia-corrected serum sodium level (SNa) < 135 mmol/L. Variables were collected at admission, at 2nd-3rd day of hospitalization, and ensuing days when hyponatremia persisted. Admission volemia (based on both physical and analytical parameters), therapy, and its adequacy as a function of volemia, were determined.

Results

Age: 68 years [56-81]; 39.9% were female. Median admission SNa was 133 mmol/L [131- 134]. Hyponatremia was mild (SNa 131-134 mmol/L) in 188/247 (76%). Volemia was available in 208/247 patients; 57.2% were euvolemic and the rest (42.8%) hypovolemic. Hyponatremia was left untreated in 154/247 (62.3%) patients. Admission therapy was not concordant with volemia in 43/84 (51.2%). In fact, the majority of treated euvolemic patients received incorrect therapy with isotonic saline (37/41, 90.2%), whereas hypovolemics did not (p=0.001). The latter showed higher mortality rates than those receiving adequate or no therapy (36.7% vs. 19% respectively, p=0.023). The administration of isotonic saline to euvolemic hyponatremic subjects was independently associated with an elevation of in-hospital mortality (Odds Ratio: 3.877, 95%; Confidence Interval: 1.25-12.03).

Conclusion

Hyponatremia in COVID-19 is predominantly euvolemic. Isotonic saline infusion therapy in euvolemic hyponatremic COVID-19 patients can lead to an increased mortality rate. Thus, an exhaustive and precise volemic assessment of the hyponatremic patient with CAP, particularly when due to COVID-19, is mandatory before instauration of therapy, even when hyponatremia is mild.

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.

Factors affecting prognosis of the patients with severe hyponatremia

INTRODUCTION

Hyponatremia is one of the most common electrolyte abnormalities in clinical practice. Data regarding factors that have impact on mortality of severe hyponatremia and outcomes of its therapeutic management is insufficient. The present study aimed to examine the factors associated with mortality and the outcomes of treatment in patients with severe hyponatremia.

MATERIALS AND METHODS

Patients with serum Na≤115mequiv./L who were admitted to Ordu State Hospital and Ordu University Training and Research Hospital between 2014 and 2018 were included in the study. Demographic and laboratory features, severity of the symptoms, comorbid diseases, medications, and clinical outcome measures of the patients were obtained retrospectively from their medical records. Factors associated with in-hospital mortality, overcorrection and undercorrection were assessed.

RESULTS

A total of 145 patients (median age 69 years and 58.6% female) met inclusion criteria. Diuretic use was the most common etiologic factor for severe hyponatremia that present in 50 (34.5%) patients. Sixty-seven (46.2%) patients had moderately severe while 8 patients (5.5%) had severe symptoms. The median increase in serum Na 24h after admission in the study population was 8.9mequiv./L (-6 to 19). Nonoptimal correction was seen in 92 (63.4%) patients. Hypertonic saline use was associated with overcorrection (OR, 3.07; 95% CI: 1.47-6.39; p=0.002). Avoidance of hypertonic saline (aOR, 2.52; 95% CI: 1.12-5.66; p=0.029) and having neuropsychiatric disorder (aOR, 2.60; 95% CI: 1.10-6.11; p=0.025) were associated with undercorrection. In-hospital mortality rate was 12.4% and having CKD and cancer, undercorrection of sodium and presence of severe symptoms were significantly associated with in-hospital mortality.

CONCLUSION

Severe hyponatremia in hospitalized patients is associated with substantial mortality. The incidence of non-optimal correction of serum Na is high; under-correction, presence of severe symptoms, chronic kidney disease and cancer were the factors that increase mortality rate.

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

Introduction:

Methods:

Results:

Conclusion:

Factors affecting prognosis of the patients with severe hyponatremia

INTRODUCTION

Hyponatremia is one of the most common electrolyte abnormalities in clinical practice. Data regarding factors that have impact on mortality of severe hyponatremia and outcomes of its therapeutic management is insufficient. The present study aimed to examine the factors associated with mortality and the outcomes of treatment in patients with severe hyponatremia.

MATERIALS AND METHODS

Patients with serum Na≤115mequiv./L who were admitted to Ordu State Hospital and Ordu University Training and Research Hospital between 2014 and 2018 were included in the study. Demographic and laboratory features, severity of the symptoms, comorbid diseases, medications, and clinical outcome measures of the patients were obtained retrospectively from their medical records. Factors associated with in-hospital mortality, overcorrection and undercorrection were assessed.

RESULTS

A total of 145 patients (median age 69 years and 58.6% female) met inclusion criteria. Diuretic use was the most common etiologic factor for severe hyponatremia that present in 50 (34.5%) patients. Sixty-seven (46.2%) patients had moderately severe while 8 patients (5.5%) had severe symptoms. The median increase in serum Na 24h after admission in the study population was 8.9mequiv./L (-6 to 19). Nonoptimal correction was seen in 92 (63.4%) patients. Hypertonic saline use was associated with overcorrection (OR, 3.07; 95% CI: 1.47-6.39; p=0.002). Avoidance of hypertonic saline (aOR, 2.52; 95% CI: 1.12-5.66; p=0.029) and having neuropsychiatric disorder (aOR, 2.60; 95% CI: 1.10-6.11; p=0.025) were associated with undercorrection. In-hospital mortality rate was 12.4% and having CKD and cancer, undercorrection of sodium and presence of severe symptoms were significantly associated with in-hospital mortality.

CONCLUSION

Severe hyponatremia in hospitalized patients is associated with substantial mortality. The incidence of non-optimal correction of serum Na is high; under-correction, presence of severe symptoms, chronic kidney disease and cancer were the factors that increase mortality rate.

A cross-sectional survey of knowledge pertaining to IV fluid therapy and hyponatraemia among nurses working at emergency departments in Denmark

INTRODUCTION

Inappropriate fluid therapy may induce or worsen existing hyponatraemia with potentially life-threatening consequences. Nurses have an important role in assisting physicians in IV fluid prescribing. However, research is lacking in Denmark about nurses' knowledge pertaining to IV fluid therapy and hyponatraemia.

METHODS

An explorative cross-sectional survey was performed among Danish emergency department nurses in Spring 2019. Knowledge about IV fluid therapy was assessed for three common clinical scenarios, and multiple-choice questions were used to measure knowledge about hyponatraemia.

RESULTS

112 nurses responded to all scenario questions corresponding to 6.2% (112/1815) of the total population of nurses working at emergency departments in Denmark. In two of the three scenarios, a minority of nurses (8-10%) inappropriately selected hypotonic fluids. Nearly one third (31%) selected a hypotonic fluid for a patient with meningitis, which is against guideline recommendations. The study revealed limited knowledge about severe symptoms of hyponatraemia, patients at high risk, and hyperglycaemia-induced hyponatraemia.

CONCLUSION

In accordance with guideline recommendation, the majority of nurses did not select hypotonic fluids in three clinical scenarios commonly encountered in the emergency department. However, when setting up an educational program, further awareness is needed regarding symptoms of hyponatraemia, high-risk patients, and hyperglycaemia-induced hyponatraemia.

Risk of Adverse Clinical Outcomes in Hyponatremic Adult Patients Hospitalized for Acute Medical Conditions: A Population-Based Cohort Study

CONTEXT

Hyponatremia has been associated with excess long-term morbidity and mortality. However, effects during hospitalization are poorly studied.

OBJECTIVE

The objective of this work is to examine the association of hyponatremia with the risk of in-hospital mortality, 30-day readmission, and other short-term adverse events among medical inpatients.

DESIGN AND SETTING

A population-based cohort study was conducted using a Swiss claims database of medical inpatients from January 2012 to December 2017.

PATIENTS

Hyponatremic patients were 1:1 propensity-score matched with normonatremic medical inpatients.

MAIN OUTCOME MEASURE

The primary outcome was a composite of all-cause in-hospital mortality and 30-day hospital readmission. Secondary outcomes were intensive care unit (ICU) admission, intubation rate, length-of-hospital stay (LOS), and patient disposition after discharge.

RESULTS

After matching, 94 352 patients were included in the cohort. Among 47 176 patients with hyponatremia, 8383 (17.8%) reached the primary outcome compared with 7994 (17.0%) in the matched control group (odds ratio [OR] 1.06 [95% CI, 1.02-1.10], P = .001). Hyponatremic patients were more likely to be admitted to the ICU (OR 1.43 [95% CI, 1.37-1.50], P < .001), faced a 56% increase in prolonged LOS (95% CI, 1.52-1.60, P < .001), and were admitted more often to a postacute care facility (OR 1.38 [95% CI 1.34-1.42, P < .001). Of note, patients with the syndrome of inappropriate antidiuresis (SIAD) had lower in-hospital mortality (OR 0.67 [95% CI, 0.56-0.80], P < .001) as compared with matched normonatremic controls.

CONCLUSION

In this study, hyponatremia was associated with increased risk of short-term adverse events, primarily driven by higher readmission rates, which was consistent among all outcomes except for decreased in-hospital mortality in SIAD patients.

Are Further Interventions Needed to Prevent and Manage Hospital-Acquired Hyponatraemia? A Nationwide Cross-Sectional Survey of IV Fluid Prescribing Practices

BACKGROUND

Hyponatraemia is associated with increased morbidity, increased mortality and is frequently hospital-acquired due to inappropriate administration of hypotonic fluids. Despite several attempts to minimise the risk, knowledge is lacking as to whether inappropriate prescribing practice continues to be a concern.

METHODS

A cross-sectional survey was performed in Danish emergency department physicians in spring 2019. Prescribing practices were assessed by means of four clinical scenarios commonly encountered in the emergency department. Thirteen multiple-choice questions were used to measure knowledge.

RESULTS

201 physicians responded corresponding to 55.4% of the total population of physicians working at emergency departments in Denmark. About a quarter reported that they would use hypotonic fluids in patients with increased intracranial pressure and 29.4% would use hypotonic maintenance fluids in children, both of which are against guideline recommendations. Also, 29.4% selected the correct fluid, a 3% hypertonic saline solution, for a patient with hyponatraemia and severe neurological symptoms, which is a medical emergency. Most physicians were unaware of the impact of hypotonic fluids on plasma sodium in acutely ill patients.

CONCLUSION

Inappropriate prescribing practices and limited knowledge of a large number of physicians calls for further interventions to minimise the risk of hospital-acquired hyponatraemia.

Tolvaptan Versus Fluid Restriction in the Treatment of Hyponatremia Resulting from SIADH Following Pituitary Surgery

Context

The relevance of hyponatremia has been acknowledged by guidelines from the United States (2013) and Europe (2014). However, treatment recommendations differ due to limited evidence.

Objective

In hyponatremia following pituitary surgery-caused by the syndrome of inappropriate antidiuretic hormone (SIADH) secretion-we compared fluid restriction with the pharmacological increase of water excretion by blocking the vasopressin 2 receptors with tolvaptan at a low and a moderate dose.

Design

Prospective observational study.

Setting

Neurosurgical Department of a University hospital with more than 200 surgical pituitary procedures per year.

Patients

Patients undergoing pituitary surgery and developing serum sodium below 136 mmol/L. The diagnosis of SIADH was established by euvolemia (daily measurement of body weight and fluid balance), inappropriately concentrated urine (specific gravity), and exclusion of adrenocorticotropic and thyroid-stimulating hormone deficiency.

Intervention

Patients were treated with fluid restriction (n = 40) or tolvaptan at 3.75 (n = 38) or 7.5 mg (n = 48).

Main Outcome Measures

Treatment efficacy was assessed by the duration of hyponatremia, sodium nadir, and length of hospitalization. Safety was established by a sodium increment below 10 mmol/L per day and exclusion of side effects.

Results

Treatment with 7.5 mg of tolvaptan resulted in a significant attenuation of hyponatremia and in a significant overcorrection of serum sodium in 30% of patients. The duration of hospitalization did not differ between treatment groups.

Conclusions

Tolvaptan at a moderate dose is more effective than fluid restriction in the treatment of SIADH. Overcorrection of serum sodium may be a side effect of tolvaptan even at low doses.

[Hyponatremia-workflow for intensive care physicians]

Hyponatremia (sodium <135 mmol/l) is the most common electrolyte disorder. Despite identical serum concentrations, clinical symptomatology can vary greatly from mild to life-threatening. Accordingly, individual patients require immediate active treatment, while the majority of (mostly oligosymptomatic) patients should first undergo differentiated diagnosis. The most important element is the assessment of the clinical situation of the patient and never isolated laboratory chemical constellations: "Treat the patient, not the numbers".

Clinico-etiological profile of hyponatremia among elderly age group patients in a tertiary care hospital in Sikkim

Background

Hyponatremia is a common condition observed in hospitalized patients. The incidence is much more in the elderly patients owing to impaired ability to maintain water and electrolyte homeostasis. It is important to evaluate and understand the causes and patient characteristics in order to deliver precise management.

Materials and Methods

Study was conducted at a teaching referral hospital in Sikkim and total of 100 elderly patients, diagnosed with hyponatremia, were enrolled in the study. Detailed medical history, clinical and laboratory examination were performed and data including treatment details were collected. Descriptive analysis was performed and results were correlated with patient characteristics.

Results

Mean age of the patients was 73.87 ± 6.54 years with a male to female ratio of 1:0.96. About 81% of patients were symptomatic among which lethargy (50%), drowsiness (40%), and abnormal behavior (39%) were common symptoms. Most patients (51%) had profound hyponatremia and Syndrome of inappropriate antidiuretic hormone secretion (SIADH) (36%) and drugs (26%) were the most common cause of hyponatremia in this study. The common treatment given in this study was 0.9% NaCl (71%). Mortality of patients in this study was 20%.

Conclusion

Clinicians need to be aware of the common occurrence of hyponatremia in the elderly, especially acutely sick elderly. A systematic approach to its diagnosis with the application of simple standardized diagnostic algorithms can significantly improve the assessment and management of hyponatremia as the outcome in profound hyponatremia is governed by etiology, and not by the serum sodium level.

Investigation and management of moderate to severe inpatient hyponatraemia in an Australian tertiary hospital

BACKGROUND

Hyponatraemia is the most common electrolyte disturbance amongst hospitalised patients. Both American and European guidelines recommend fluid restriction as first line treatment for SIADH, however differ on second line recommendations. The objective of this study was to examine investigation and management of hyponatraemia in hospitalised patients in an Australian tertiary hospital.

METHODS

A retrospective audit was conducted of electronic medical records and laboratory data of inpatients with serum sodium (Na) ≤125 mmol/L, admitted over a 3 month period to the Princess Alexandra Hospital, Brisbane, Australia. The main outcomes measured included: demographic characteristics, investigations, accuracy of diagnosis, management strategy, change in Na and patient outcomes.

RESULTS

The working clinical diagnosis was considered accurate in only 37.5% of cases. Urine Na and osmolality were requested in 72 of 152 patients (47.4%) and in 43 of 70 euvolaemic patients (61.4%). Thyroid function tests (67.1%) and morning cortisol (45.7%) were underutilized in the euvolaemic group. In the SIADH cohort, fluid restriction resulted in a median (IQR) 7.5 mmol/L (4-10.5) increase in Na after 3 days; no treatment resulted in a median 0 mmol/L (- 0.5-1.5) change. Oral urea was utilized in 5 SIADH patients where Na failed to increase with fluid restriction alone. This resulted in a median 10.5 mmol/L (3.5-13) increase in Na from baseline to day 3. There were no cases of osmotic demyelination. The median length of stay was 8 days (4-18.5). Mortality was 11.2% (17 patients). There was a weak but significant correlation between nadir serum Na and mortality (R = 0.18, P = 0.031).

CONCLUSION

Inpatient hyponatraemia is often inadequately investigated, causing errors in diagnosis. Treatment is heterogeneous and often incorrect. In cases with hyponatraemia refractory to fluid restriction, oral urea presents an effective alternative treatment.

Anti-Voltage-Gated Potassium Channel Antibody Syndrome: A Rare Cause of Hyponatremia in Intensive Care Unit

Hyponatremia causing seizure is a common cause for admission in the critical care unit. Here, we describe a peculiar case of seizure due to hyponatremia, associated with anti-voltage-gated potassium channel antibody syndrome. This case emphasizes that how a proper workup can unveil unusual but potentially treatable causes of hyponatremia. The hallmark of this syndrome is that neurological symptoms may relapse or progress if the disorder is not recognized in time. This case report emphasizes the point that how a keen observation may decode subtle signs of the grave but potentially treatable pathologies.

In-patient Tolvaptan use in SIADH: care audit, therapy observation and outcome analysis

BACKGROUND

Indications for use of tolvaptan in SIADH-associated hyponatraemia remain controversial. We audited our local guidelines for Tolvaptan use in this situation to review treatment implications including drug safety, hospital admission episode analysis (episodes of liver toxicity, CNS myelinolysis, sodium-related re-admission rates), morbidity; mortality and underlying aetiologies.

METHODS

We report a retrospective case series analysis of on-going treatment outcomes (case-note review) for 31 patients (age 73.3 ± 10.5 years, 55% females) consecutively treated with Tolvaptan as in-patient for confirmed SIADH with persistent S/Na⁺ < 125 mmol/L despite removal of reversible causes and 24-48 h fluid restriction, and include longer-term outcome data (re-treatment/readmissions/mortality) for up to 4 years of follow-up. A minimum of 6 months follow-up data were reviewed unless the patient died before that period.

RESULTS

Short-term outcomes were favourable; 94%-achieved treatment targets after a mean of 3.48 ± 2.46 days. There was statistically significant rise in S/Na⁺ level after Tolvaptan treatment (before treatment: mean sodium 117.8 ± 3.73, 108-121 mmol/L and after treatment: mean sodium 128.7 ± 3.67, 125-135.2 mmol/L, P < .001). Although the target S/Na⁺ level was >125 mmol/L in fact one third (35%) of the patients achieved a S/Na⁺ level of >130 mmol/L by the time of hospital discharge. No patient experienced S/Na⁺ rise >12 mmol/L/24 h, drug-associated liver injury or CNS-myelinolysis. The average length of hospital stay following start of Tolvaptan treatment was 3.2 days. Relapse of hyponatraemia occurred in 26% of the patients, requiring retreatment with Tolvaptan. In all patients where either relapse of hyponatraemia occurred or readmission was necessary, SIADH was associated with malignancy, which was present overall in 60% of the group studied.

CONCLUSIONS

This study confirms the safety and efficacy of Tolvaptan in the treatment of SIADH-related significant, symptomatic hyponatraemia when used under specialist guidance and strict monitoring. A sodium level relapsing below the treatment threshold by 1 week after discontinuation is a good indicator of a patient group with re-treatment/longer-term therapy needs, all of whom had underlying malignancy. The criteria set locally in our trust to initiate Tolvaptan use also identifies a group where further investigation for underlying malignancy should be considered.

Mortality rates are lower in SIAD, than in hypervolaemic or hypovolaemic hyponatraemia: Results of a prospective observational study

OBJECTIVE

Hyponatraemia is associated with increased mortality, but the mortality associated specifically with SIAD is not known. We hypothesized that mortality in SIAD was elevated, but that it was less than in hypervolaemic (HEN) or hypovolaemic (HON) hyponatraemia.

DESIGN

Mortality rates are presented as risk ratios (RR),with 95% confidence intervals (CI), and compared to normonatraemic controls (NN).

METHODS

Prospective, single centre, noninterventional study of all patients with hyponatraemia (≤130 mmol/L) admitted to hospital.

RESULTS

A total of 1323 admissions with hyponatraemia were prospectively evaluated and 1136 contemporaneous NN controls. 431(32.6%) hyponatraemic patients had HON, 573(43.3%) had SIAD and 275(20.8%) patients had HEN. In patient mortality was higher in hyponatraemia than NN (9.1% vs 3.3%, P<.0001). The RRs for in-hospital mortality compared to NN were: SIAD, 1.76 (95% CI 1.08-2.8, P=.02), HON 2.77 (95% CI 1.8-4.3, P<.0001) and HEN, 4.9 (95% CI 3.2-7.4, P<.0001). The mortality rate was higher in HEN (RR 2.85; 95% CI 1.86-4.37, P<.0001) and in HON, (RR 1.6; 95% CI 1.04-2.52; P=.03), when compared to SIAD. The Charlson Comorbidity Index was lower in SIAD than in eunatraemic patients (P<.0001). 9/121(7.4%) patients died with plasma sodium <125 mmol/L and 4(3.3%) with plasma sodium <120 mmol/L. However, 69/121(57%) patients died with a plasma sodium above 133 mmol/L.

CONCLUSIONS

We confirmed higher all-cause mortality in hyponatraemia than in NN. Mortality was higher in SIAD than in normonatraemia and was not explained on the basis of co-morbidities. Mortality was higher in HON and HEN than in SIAD. Mortality rates reported for all-cause hyponatraemia in the medical literature are not applicable to SIAD.

Efficacy and safety of two different tolvaptan doses in the treatment of hyponatremia in the Emergency Department

Hyponatremia (plasma sodium concentration or _P[Na⁺] <136 mEq/L) is the most common electrolyte unbalance in clinical practice. Although it constitutes a negative prognostic factor, it frequently remains underdiagnosed and undertreated. Tolvaptan is an oral V₂-receptor antagonist which produces aquaresis. Given its emerging role in the treatment of dilutional hyponatremia, we aimed to compare the efficacy and safety of two different doses of this drug in an Emergency Department (ED) setting. Consecutive patients with moderate-severe euvolemic or hypervolemic hyponatremia were sequentially assigned to the 15 mg Group and to the 7.5 mg Group, and were revaluated at 6, 12 and 24 h. Further evaluations and administrations were scheduled daily until _P[Na⁺] correction was achieved or the maximum period of 72 h was exceeded. A 1-month follow-up was performed. Twenty-three patients were enrolled: 12 were included in the 15 mg Group, 11 in the 7.5 mg Group. Both doses significantly elevated the _P[Na⁺] over 24 h, although the 15 mg Group showed faster corrections than the 7.5 mg Group (12 vs 6 mEq/L/24 h; P = 0.025). An optimal correction rate (within 4-8 mEq/L/24 h) was observed in 45.4 % of the 7.5 mg Group against 25.0 % (P n.s.). The standard dose led to dangerous overcorrections (>12 mEq/L/24 h) in 41.7 % of the patients, while the low dose did not cause any (P = 0.037). No osmotic demyelination syndrome was observed. A 7.5 mg tolvaptan dose can be considered both effective and safe in treating hyponatremia in the ED, while a 15 mg dose implicates too high risk of overcorrection.

[Hyponatremia in emergency admissions - often dangerous]

Hyponatremia is the most common electrolyte disorder in clinical practice and associated with increased morbidity and mortality, independent of underlying disease. Untreated acute hyponatremia can cause substantial morbidity and mortality as a result of osmotically induced cerebral edema whilst over rapid correction of chronic hyponatremia can cause serious neurologic impairment and death resulting from osmotic demyelination. Still hyponatremia is often neglected and insufficiently addressed, most likely due to limited understanding of its pathophysiological mechanisms. Being familiar with only few basic principles of body fluid regulation may be a worthwhile investment into the clinical career and save patients' lives.

Development of a computer-interpretable clinical guideline model for decision support in the differential diagnosis of hyponatremia

INTRODUCTION

Hyponatremia is the most common type of electrolyte imbalance, occurring when serum sodium is below threshold levels, typically 135mmol/L. Electrolyte balance has been identified as one of the most challenging subjects for medical students, but also as one of the most relevant areas to learn about according to physicians and researchers. We present a computer-interpretable guideline (CIG) model that will be used for medical training to learn how to improve the diagnosis of hyponatremia applying an expert consensus document (ECDs).

METHODS

We used the PROForma set of tools to develop the model, using an iterative process involving two knowledge engineers (a computer science Ph.D. and a preventive medicine specialist) and two expert endocrinologists. We also carried out an initial validation of the model and a qualitative post-analysis from the results of a retrospective study (N=65 patients), comparing the consensus diagnosis of two experts with the output of the tool.

RESULTS

The model includes over two-hundred "for", "against" and "neutral" arguments that are selectively triggered depending on the input value of more than forty patient-state variables. We share the methodology followed for the development process and the initial validation results, that achieved a high ratio of 61/65 agreements with the consensus diagnosis, having a kappa value of K=0.86 for overall agreement and K=0.80 for first-ranked agreement.

CONCLUSION

Hospital care professionals involved in the project showed high expectations of using this tool for training, but the process to follow for a successful diagnosis and application is not trivial, as reported in this manuscript. Secondary benefits of using these tools are associated to improving research knowledge and existing clinical practice guidelines (CPGs) or ECDs. Beyond point-of-care clinical decision support, knowledge-based decision support systems are very attractive as a training tool, to help selected professionals to better understand difficult diseases that are underdiagnosed and/or incorrectly managed.

Euvolemic hyponatremia in cancer patients. Report of the Hyponatremia Registry: an observational multicenter international study

Purpose

Hyponatremia secondary to SIADH is frequent in cancer patients and potentially deleterious. The aim of this sub-analysis of the Hyponatremia Registry database is to analyze current diagnostic and therapeutic management practices in cancer patients with SIADH.

Methods

We analyzed 358 cancer patients who had serum sodium concentration ([Na⁺]) ≤ 130 mEq/L and a clinical diagnosis of SIADH from 225 sites in the USA and EU.

Results

Precise diagnostic testing was performed in only 46%. Almost 12% of all patients did not receive any hyponatremia treatment. The most frequent therapies were fluid restriction (20%), isotonic saline (14%), fluid restriction/isotonic saline (7%), tolvaptan (8%), and salt tablets (7%). Hypertonic saline was used in less than 3%. Tolvaptan produced the greatest median rate of [Na⁺] change (IQR) (3.0 (4.7) mEq/L/day), followed by hypertonic saline (2.0(7.0) mEq/L/day), and fluid restriction/isotonic saline (1.9(3.2) mEq/L/day). Both fluid restriction and isotonic saline monotherapies were significantly less effective (0.8(2.0) mEq/L/day and 1.3(3.0) mEq/L/day, respectively) and were associated with clinically relevant rates of treatment failure. Only 46% of patients were discharged with [Na⁺] ≥ 130 mEq/L. Overly rapid correction of hyponatremia occurred in 11.7%.

Conclusions

Although essential for successful hyponatremia management, appropriate diagnostic testing is not routinely performed in current practice. The most frequently employed monotherapies were often ineffective and sometimes even aggravated hyponatremia. Tolvaptan was used less often but showed significantly greater effectiveness. Despite clear evidence that hyponatremia is associated with poor outcome in oncology patients, most patients were discharged still hyponatremic. Further studies are needed to assess the beneficial impact of hyponatremia correction with effective therapies.

Electronic supplementary material

The online version of this article (doi:10.1007/s00520-017-3638-3) contains supplementary material, which is available to authorized users.

SIADH: differential diagnosis and clinical management

Despite the widespread prevalence of hyponatremia and its deleterious effects on patients, it is often overlooked and consequently undertreated. This set of four cases provides practical advice on how to identify, diagnose, and treat patients with syndrome of inappropriate antidiuretic hormone (SIADH). The first steps that a physician should take when diagnosing a patient with hyponatremia are to assess the severity of neurological symptoms, and check the patient's volemic status in order to determine whether emergency treatment with hypertonic saline is indicated. Laboratory tests are necessary for the diagnosis of SIADH, but, in severe, symptomatic cases of hyponatremia, patients need treatment before the results of laboratory tests can be obtained. In this series, Case 1 demonstrates how awareness of hyponatremia led to early diagnosis and treatment. Case 2 demonstrates how multiple causes of hyponatremia can be diagnosed and managed sequentially. Case 3 illustrates how a patient with severe symptoms should be treated while waiting for laboratory test results to confirm diagnosis. Case 4 examines how the priorities of a patient should inform the management of their chronic SIADH, using palliative care of a patient with small-cell lung cancer as an example. There are several factors that clinicians should consider when making treatment decisions, including signs and symptoms, risks and benefits of different treatments, psychosocial factors, and the patient's wishes. All the available treatment options have a place in the management of patients with SIADH, and a physician should individualize decisions based on a patient's needs and priorities.

The contribution of undiagnosed adrenal insufficiency to euvolaemic hyponatraemia: results of a large prospective single-centre study

OBJECTIVE

The syndrome of inappropriate antidiuresis (SIAD) is the commonest cause of hyponatraemia. Data on SIAD are mainly derived from retrospective studies, often with poor ascertainment of the minimum criteria for the correct diagnosis. Reliable data on the incidence of adrenal failure in SIAD are therefore unavailable. The aim of the study was to describe the aetiology of SIAD and in particular to define the prevalence of undiagnosed adrenal insufficiency.

DESIGN

Prospective, single centre, noninterventional, observational study of patients admitted to Beaumont Hospital with euvolaemic hyponatraemia (plasma sodium ≤ 130 mmol/l) between January 1st and October 1st 2015.

PATIENTS

A total of 1323 admissions with hyponatraemia were prospectively evaluated; 576 had euvolaemic hyponatraemia, with 573 (43·4%) initially classified as SIAD.

MAIN OUTCOME MEASURES

(i) Aetiology of SIAD, defined by diagnostic criteria; (ii) Incidence of adrenal insufficiency.

RESULTS

Central nervous system diseases were the commonest cause of SIAD (n = 148, 26%) followed by pulmonary diseases (n = 111, 19%), malignancy (n = 105, 18%) and drugs (n = 47, 8%). A total of 22 patients (3·8%), initially diagnosed as SIAD, were reclassified as secondary adrenal insufficiency on the basis of cortisol measurements and clinical presentation; 9/22 cases had undiagnosed hypopituitarism; 13/22 patients had secondary adrenal insufficiency due to exogenous steroid administration.

CONCLUSIONS

In a large, prospective and well-defined cohort of euvolaemic hyponatraemia, undiagnosed secondary adrenal insufficiency co-occurred in 3·8% of cases initially diagnosed as SIAD. Undiagnosed pituitary disease was responsible for 1·5% of cases presenting as euvolaemic hyponatraemia.

Prognosis of patients with severe hyponatraemia is related not only to hyponatraemia but also to comorbidities and to medical management: results of an observational retrospective study

Background

The true cause of death in severe hyponatraemic patients remains controversial. The present study aimed to analyse the relationship between comorbidity, medical management and prognosis in severe hyponatraemic patients.

Methods

Medical records of all patients hospitalised in our institution in 2012 with a plasma sodium ≤120 mmol/l were retrospectively analysed.

Results

One hundred forty-seven of 64 723 adult patients (0.2 %) were identified with severe hyponatraemia. In-hospital mortality rate was 24.5 and 50.3 % after a median follow-up of 431 days. Patients with plasma sodium <110 mmol/l had less comorbidity (Charlson Comorbidity Index 2.2 ± 1.9 vs. 4.0 ± 3.1 (plasma sodium 110–115 mmol/l) and 4.2 ± 3.1 (plasma sodium 116–120 mmol/l); P = .02)) and a small trend for less mortality, respectively 40.0, 51.2 and 52.3 % (P = .64). At discharge, nonsurvivors and survivors had similar plasma sodium with 58.3 % of nonsurvivors being normonatraemic. Urine analysis was performed in 74.2 % of cases and associated with lower in-hospital mortality (20.2 % vs. 36.8 %, P = .05). In multivariate Cox analysis, mortality was significantly associated with plasma sodium normalisation (HR 0.35, P < 0.001), urine analysis (HR 0.48, P = .01), Charlson Comorbidity Index (HR 1.23, P < .001) and serum albumin (HR 0.88, P < .001).

Conclusion

Mortality in severe hyponatraemia appears mainly due to comorbidities although the latter are potentiated by hyponatraemia itself and its management thereby exacerbating the risk of death.

SIAD: practical recommendations for diagnosis and management

Hyponatremia is the commonest electrolyte disturbance encountered in hospitalized patients, and the syndrome of inappropriate antidiuresis (SIAD) is the most frequent underlying disorder. There is a well-recognized relationship between hyponatremia and increased morbidity and mortality. Therefore, to provide appropriate treatment is critical to improve the clinical outcome related to SIAD-hyponatremia. There have been important advances in the treatment of SIAD over the last decade, leading to the publication of several clinical guidelines. In particular, the introduction of the vasopressin-2 receptor antagonists provides a potent pharmacological tool to target the underlying pathophysiology of SIAD. The evidence base recommendations of the available therapies for SIAD are discussed in this study. Fluid restriction is considered the first-line therapy by the recent published guidelines, but it is certainly ineffective or unfeasible in many patients with SIAD. We discuss a number of relevant points to the use of fluid restriction in this study, including the lack of good evidence-based recommendations to support its use. Conversely, the clinical efficacy of oral tolvaptan in SIAD supported by good quality randomized, placebo controlled, clinical trials. However, the cost of the therapy and the need for long-term safety data may limit its widespread use. Finally, new recommendations for the management of acute hyponatremia with a focus on the use of bolus therapy with 3 % hypertonic sodium chloride are described in this study.

The burden of illness in patients with hyponatraemia in Sweden: a population-based registry study

BACKGROUND

Hyponatraemia (HN; serum sodium level < 135 mmol/l) is the most common electrolyte disturbance seen in clinical practice, and is associated with varying spectrum of symptoms. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common aetiology in hospitalised patients, and can be caused by several different underlying conditions.

AIMS

The objectives of this study were to retrospectively examine the baseline characteristics, clinical outcomes and hospital resource utilisation of patients with HN and/or SIADH in Sweden over a 10-year period from 2001 to 2011. Additional analysis was performed on subpopulations of patients with hip fracture, pneumonia and small cell lung cancer (SCLC) to see if trends in outcomes were consistent across a broad range of aetiologies commonly associated with the condition.

METHODS

Patient information was taken from the Swedish National Patient Registry, the Swedish Cancer Registry, the Swedish Cause of Death Register and the Swedish Prescribed Drug Register. A total of 34,537 patients (4.38%) were identified with HN and/or SIADH, with the incidence and prevalence rising over the 10-year study period.

RESULTS

Of the 34,537 patients identified, 841 had hip fracture, 2635 had pneumonia and 106 had SCLC. Compared with matched control patients, those with HN and/or SIADH had a longer length of hospital stay, a higher re-admission rate and a shorter time to re-admission.

CONCLUSIONS

This study showed that HN and/or SIADH negatively impact patient outcomes and healthcare resources related to hospital stay irrespective of the underlying cause. The impact of HN is not confined to the initial hospitalisation, as re-admission rates are also affected.

[The rate of hyponatremia in neurosurgical patients (comparison between the data from the Burdenko Neurosurgical Instutite and the literature) and recommendations for the diagnosis and treatment]

Hyponatremia is a relatively frequent and serious complication in patients with various neurosurgical pathologies.

OBJECTIVE

This study is aimed at assessing the incidence of hyponatremia in neurosurgical patients depending on the pathology.

MATERIAL AND METHODS

This paper presents a retrospective analysis 39 479 cases of patients operated on at the Burdenko Neurosurgical Institute from 2008 to 2014.

RESULTS

A total of 785 hyponatremic patients with Na level lower than 130 mmol/l (2% of all operated patients) were identified. Mortality in patients with hyponatremia was 14.3%, which is tenfold higher compared to the rest of population of patients without hyponatremia who were operated on during the same period. In adults, hyponatremia most frequently occurred after resection of craniopharyngiomas (11%) and as a result of acute cerebrovascular accident (22%). In children, it occurred after resection of craniopharyngiomas (10%), astrocytomas (7%), ependymomas (24%), and germ cell tumors (10.5%).

CONCLUSION

This study, which was mainly statistical one, was not aimed at detailed investigation of hyponatremia in different groups of neurosurgical patients. We only tried to draw the attention of various experts to those categories of patients, where focused and in-depth developments are more than important. Obviously, already gained international experience should be taken into account for this

PURPOSE

Therefore, this article presents the literature data on the etiology and pathogenesis of hyponatremia. We describe the details of the various classifications of hyponatremia, its clinical symptoms, diagnosis, and treatments, primarily based on the recommendations of the last European consensus of various specialists (2014).

The diagnosis and management of inpatient hyponatraemia and SIADH

BACKGROUND

Hyponatraemia is a very common medical condition that is associated with multiple poor clinical outcomes and is often managed suboptimally because of inadequate assessment and investigation. Previously published guidelines for its management are often complex and impractical to follow in a hospital environment, where patients may present to divergent specialists, as well as to generalists.

DESIGN

A group of senior, experienced UK clinicians, met to develop a practical algorithm for the assessment and management of hyponatraemia in a hospital setting. The latest evidence was discussed and reviewed in the light of current clinical practicalities to ensure an up-to-date perspective. An algorithm was largely developed following consensus opinion, followed up with subsequent additions and amendments that were agreed by all authors during several rounds of review.

RESULTS

We present a practical algorithm which includes a breakdown of the best methods to evaluate volume status, simple assessments for the diagnosis of the various causes and a straightforward approach to treatment to minimise complexity and maximise patient safety.

CONCLUSION

The algorithm we have developed reflects the best available evidence and extensive clinical experience and provides practical, useable guidance to improve patient care.

Hyponatremia secondary to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH): therapeutic decision-making in real-life cases

Despite being the most common electrolyte disturbance encountered in clinical practice, the diagnosis and treatment of hyponatremia (defined as a serum sodium concentration <135 mmol/L) remains far from optimal. This is extremely troubling because not only is hyponatremia associated with increased morbidity, length of hospital stay and hospital resource use, but it has also been shown to be associated with increased mortality. The reasons for this poor management may partly lie in the heterogeneous nature of the disorder; hyponatremia presents with a variety of possible etiologies, differing symptomology and fluid volume status, thereby making its diagnosis potentially complex. In addition, a general lack of awareness of the clinical impact of the disorder, a fear of adverse outcomes through overcorrection of sodium levels, and a lack of effective targeted treatments until recent years, may all have contributed to a reticence to actively treat cases of hyponatremia. There is therefore a clear unmet need to further educate physicians on the pathophysiology, diagnosis and management of this important condition. Through the use of a variety of real-world cases of patients with hyponatremia secondary to the syndrome of inappropriate secretion of antidiuretic hormone—a condition that accounts for approximately one-third of all cases of hyponatremia—this supplement aims to provide a comprehensive overview of the challenges faced in diagnosing and managing hyponatremia. These cases will also help to illustrate how some of the limitations of traditional therapies may be overcome with the use of vasopressin receptor antagonists.

[Hyponatremia and tolvaptan : what is the situation 5 years after approval?]

The diuretic tolvaptan has been approved for more than 5 years for the indications of euvolemic hyponatremia due to syndrome of inappropriate antidiuretic hormone (SIADH) secretion. In recent years many patients have been treated with tolvaptan and many physicians could gather practical experience. Other countries, such as the USA had already gained greater experience, also in the indications for hypervolemic hyponatremia. After approval was granted more than 5000 patients worldwide were included in the so-called hyponatremia register and 22 active centers in Germany with 317 patients participated. Although some details from this now concluded register have been published, the final publication of the multinational post-authorization safety study on tolvaptan in the treatment of SIADH has not yet been published. In the years 2012 and 2013 two warning letters were issued on tolvaptan. The first letter warned of the risk of a faster increase in serum sodium using tolvaptan and provided detailed information on how the risk of osmotic demeyelination can be minimized. So far only one proven case of osmotic demelination syndrome (ODS) is known; however, this occurred following incorrect use of tolvaptan in a monotherapy. The second warning letter provided information on the potential risk (reversible) of liver damage by tolvaptan, which resulted from the TEMPO 3:4 study. In this study tolvaptan was used in a higher dosage for therapy of autosomal dominant polycystic kidney disease. Although the European renal best practice (ERBP) guidelines from 2014 did not recommend tolvaptan for the indications of SIADH, other guidelines came to different conclusions. In summary, 5 years after the approval of tolvaptan there is still no consensus. At the current time many questions still remain unanswered. Initiation of therapy with tolvaptan remains reserved for experienced physicians in hospitals. Treatment must be adapted on the basis of a clinical estimation of the individual situation of each patient.

The Controversies of Hyponatraemia in Hypothyroidism: Weighing the evidence

Hyponatraemia is a common electrolyte disturbance, with moderate (serum sodium: 125-129 mmol/L) to severe (serum sodium: ≤125 mmol/L) forms of the disease occurring in 4-15% of hospitalised patients. While it is relatively common, determining the underlying cause of this condition can be challenging and may require extensive laboratory investigations. To this end, it is important to ascertain the efficacy of laboratory tests in determining the cause of hyponatraemia. Up to 10% of patients with hypothyroidism also have hyponatraemia. Routine evaluation of thyroid function is often advocated in cases of low serum sodium. A review and discussion of the available literature is presented here to examine this recommendation.

Hyponatremia improvement is associated with a reduced risk of mortality: evidence from a meta-analysis

BACKGROUND

Hyponatremia is the most common electrolyte disorder and it is associated with increased morbidity and mortality. However, there is no clear demonstration that the improvement of serum sodium concentration ([Na(+)]) counteracts the increased risk of mortality associated with hyponatremia. Thus, we performed a meta-analysis that included the published studies that addressed the effect of hyponatremia improvement on mortality.

METHODS AND FINDINGS

A Medline, Embase and Cochrane search was performed to retrieve all English-language studies of human subjects published up to June 30th 2014, using the following words: "hyponatremia", "hyponatraemia", "mortality", "morbidity" and "sodium". Fifteen studies satisfied inclusion criteria encompassing a total of 13,816 patients. 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 fifteen studies, any improvement of hyponatremia was associated with a reduced risk of overall mortality (OR=0.57[0.40-0.81]). The association was even stronger when only those studies (n=8) reporting a threshold for serum [Na(+)] improvement to >130 mmol/L were considered (OR=0.51[0.31-0.86]). The reduced mortality rate persisted at follow-up (OR=0.55[0.36-0.84] at 12 months). Meta-regression analyses showed that the reduced mortality associated with hyponatremia improvement was more evident in older subjects and in those with lower serum [Na(+)] at enrollment.

CONCLUSIONS

This meta-analysis documents for the first time that improvement in serum [Na(+)] in hyponatremic patients is associated with a reduction of overall mortality.

CT-pro-AVP as a tool for assessment of intravascular volume depletion in severe hyponatremia

BACKGROUND

Assessment of volume status is essential to best manage hyponatremic patients but is not always accurate in clinical practice. The aim of this study was to evaluate the reliability of C-terminal portion of pro-arginine-vasopressin (CT-pro-AVP), a surrogate biomarker of vasopressin release, in assessing intravascular volume (IVV) depletion in hypoosmolar hyponatremic patients.

METHODS

Plasma CT-pro-AVP and urea-to-creatinine ratio (Ur/Cr) were performed in 131 hospitalized patients presenting chronic severe hypoosmolar hyponatremia. At hospital discharge, their IVV was evaluated regardless of CT-pro-AVP concentrations. All patients were then classified as decreased or as normal/expanded IVV group.

RESULTS

Plasma CT-pro-AVP levels were higher in patients with decreased IVV (34.6 vs. 11.3 pmol/L, p<0.001) and exhibited a reliable performance for assessment of decreased IVV (ROC AUC at 0.717 [95% CI 0.629-0.805]). The combination of CT-pro-AVP and Ur/Cr resulted in an improved ROC AUC up to 0.787 (95% CI 0.709-0.866).

CONCLUSIONS

Our findings support the hypothesis that CT-pro-AVP plasma level may reflect IVV and would be a tool for its assessment. This performance has been magnified by its combination with Ur/Cr. A dual-marker strategy may help clinicians to optimize the management of severe hyponatremia especially in case of confusing clinical presentations.

Current treatment practice and outcomes. Report of the hyponatremia registry

Current management practices for hyponatremia (HN) are incompletely understood. The HN Registry has recorded diagnostic measures, utilization, efficacy, and outcomes of therapy for eu- or hypervolemic HN. To better understand current practices, we analyzed data from 3087 adjudicated adult patients in the registry with serum sodium concentration of 130 mEq/l or less from 225 sites in the United States and European Union. Common initial monotherapy treatments were fluid restriction (35%), administration of isotonic (15%) or hypertonic saline (2%), and tolvaptan (5%); 17% received no active agent. Median (interquartile range) mEq/l serum sodium increases during the first day were as follows: no treatment, 1.0 (0.0–4.0); fluid restriction, 2.0 (0.0–4.0); isotonic saline, 3.0 (0.0–5.0); hypertonic saline, 5.0 (1.0–9.0); and tolvaptan, 4.0 (2.0–9.0). Adjusting for initial serum sodium concentration with logistic regression, the relative likelihoods for correction by 5 mEq/l or more (referent, fluid restriction) were 1.60 for hypertonic saline and 2.55 for tolvaptan. At discharge, serum sodium concentration was under 135 mEq/l in 78% of patients and 130 mEq/l or less in 49%. Overly rapid correction occurred in 7.9%. Thus, initial HN treatment often uses maneuvers of limited efficacy. Despite an association with poor outcomes and availability of effective therapy, most patients with HN are discharged from hospital still hyponatremic. Studies to assess short- and long-term benefits of correction of HN with effective therapies are needed.

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.

'Dos and don'ts' in the management of hyponatremia

INTRODUCTION AND OBJECTIVE

The management of hyponatremia has evolved in recent years, particularly with the introduction of tolvaptan for hyponatremia secondary to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This commentary presents a summary of recent international recommendations in the form of a series of didactic 'dos and don'ts', in order to provide concise, practical guidance for practising clinicians focused on the investigation and management of euvolemic hyponatremia (SIADH).

RESEARCH METHODS

A multidisciplinary group of international experts reviewed existing guidelines and the evidence cited within to summarize the recommendations in a practical method for use in clinical practice.

RECOMMENDATIONS

The 'dos and don'ts' are presented under topic headings that include diagnosis and diagnostic tests, specific causes, correction of acute hyponatremia, correction rates for chronic hyponatremia, management of SIADH including fluid restriction, hypertonic saline and pharmacological strategies, and management of overcorrection. Within each topic, the authors summarize the published recommendations on managing hyponatremia and the use of specific agents for the treatment of SIADH.

CONCLUSION

Practising clinicians can use these 'dos and don'ts' to provide clear, up-to-date guidance on how to manage hyponatremia and the use of tolvaptan in SIADH.

Diagnosis and treatment of hyponatremia: a systematic review of clinical practice guidelines and consensus statements

BACKGROUND

Hyponatremia is a common electrolyte disorder. Multiple organizations have published guidance documents to assist clinicians in managing hyponatremia. We aimed to explore the scope, content, and consistency of these documents.

METHODS

We searched MEDLINE, EMBASE, and websites of guideline organizations and professional societies to September 2014 without language restriction for Clinical Practice Guidelines (defined as any document providing guidance informed by systematic literature review) and Consensus Statements (any other guidance document) developed specifically to guide differential diagnosis or treatment of hyponatremia. Four reviewers appraised guideline quality using the 23-item AGREE II instrument, which rates reporting of the guidance development process across six domains: scope and purpose, stakeholder involvement, rigor of development, clarity of presentation, applicability, and editorial independence. Total scores were calculated as standardized averages by domain.

RESULTS

We found ten guidance documents; five clinical practice guidelines and five consensus statements. Overall, quality was mixed: two clinical practice guidelines attained an average score of >50% for all of the domains, three rated the evidence in a systematic way and two graded strength of the recommendations. All five consensus statements received AGREE scores below 60% for each of the specific domains.The guidance documents varied widely in scope. All dealt with therapy and seven included recommendations on diagnosis, using serum osmolality to confirm hypotonic hyponatremia, and volume status, urinary sodium concentration, and urinary osmolality for further classification of the hyponatremia. They differed, however, in classification thresholds, what additional tests to consider, and when to initiate diagnostic work-up. Eight guidance documents advocated hypertonic NaCl in severely symptomatic, acute onset (<48 h) hyponatremia. In chronic (>48 h) or asymptomatic cases, recommended treatments were NaCl 0.9%, fluid restriction, and cause-specific therapy for hypovolemic, euvolemic, and hypervolemic hyponatremia, respectively. Eight guidance documents recommended limits for speed of increase of sodium concentration, but these varied between 8 and 12 mmol/L per 24 h. Inconsistencies also existed in the recommended dose of NaCl, its initial infusion speed, and which second line interventions to consider.

CONCLUSIONS

Current guidance documents on the assessment and treatment of hyponatremia vary in methodological rigor and recommendations are not always consistent.

Treatment of hyponatremic encephalopathy with a 3% sodium chloride protocol: a case series

BACKGROUND

3% sodium chloride solution is the accepted treatment for hyponatremic encephalopathy, but evidence-based guidelines for its use are lacking.

STUDY DESIGN

A case series.

SETTING & PARTICIPANTS

Adult patients presenting to the emergency department of a university hospital with hyponatremic encephalopathy, defined as serum sodium level < 130 mEq/L with neurologic symptoms of increased intracranial pressure without other apparent cause, and treated with a continuous infusion of 500mL of 3% sodium chloride solution over 6 hours through a peripheral vein.

PREDICTORS

Hyponatremic encephalopathy defined as serum sodium level < 130 mEq/L with neurologic symptoms of increased intracranial pressure without other apparent cause.

OUTCOMES

Change in serum sodium level within 48 hours, improvement in neurologic symptoms, and clinical evidence of cerebral demyelination, permanent neurologic injury, or death within 6 months' posttreatment follow-up.

RESULTS

There were 71 episodes of hyponatremic encephalopathy in 64 individuals. Comorbid conditions were present in 86% of individuals. Baseline mean serum sodium level was 114.1±0.8 (SEM) mEq/L and increased to 117.9±1.3, 121.2±1.2, 123.9±1.0, and 128.3±0.8 mEq/L at 3, 12, 24, and 48 hours following the initiation of 3% sodium chloride solution treatment, respectively. There was a marked improvement in central nervous system symptoms within hours of therapy in 69 of 71 (97%) episodes. There were 12 deaths, all of which occurred following the resolution of hyponatremic encephalopathy and were related to comorbid conditions, with 75% of deaths related to sepsis. No patient developed neurologic symptoms consistent with cerebral demyelination at any point during the 6-month follow-up period.

LIMITATIONS

Lack of a comparison group and follow-up neuroimaging studies. Number of cases is too small to provide definitive assessment of the safety of this protocol.

CONCLUSIONS

3% sodium chloride solution was effective in reversing the symptoms of hyponatremic encephalopathy in the emergency department without producing neurologic injury related to cerebral demyelination on long-term follow-up in this case series.

Multicentre study of investigation and management of inpatient hyponatraemia in the UK

Purpose

Hyponatraemia is associated with significant morbidity and mortality. The objectives of this study were to evaluate the investigation and management of hyponatraemia and to assess the use of different therapeutic modalities and their effectiveness in routine practice.

Study design

This multicentre, retrospective, observational study was conducted at three acute NHS Trusts in March 2013. A retrospective chart review was performed on the first 100 inpatients with serum sodium (sNa) ≤128 mmol/L during hospitalisation.

Results

One hundred patients (47 male, 53 female) with a mean±SD age of 71.3±15.4 years and nadir sNa of 123.4±4.3 mmol/L were included. Only 23/100 (23%) had measurements of paired serum and urine osmolality and sodium, while 31% had an assessment of adrenal reserve. The aetiology of hyponatraemia was unrecorded in 58% of cases. The mean length of hospital stay was 17.5 days with an inpatient mortality rate of 16%. At hospital discharge, 53/84 (63.1%) patients had persistent hyponatraemia, including 20/84 (23.8%) with sNa <130 mmol/L. Overall 37/100 (37%) patients did not have any treatment for hyponatraemia. Among 76 therapeutic episodes, the most commonly used treatment modalities were isotonic saline in 38/76 cases (50%) and fluid restriction in 16/76 (21.1%). Fluid restriction failed to increase sNa by >1 mmol/L/day in 8/10 (80%) cases compared with 4/26 (15.4%) for isotonic saline.

Conclusions

Underinvestigation and undertreatment of hyponatraemia is a common occurrence in UK clinical practice. Therefore, development of UK guidelines and introduction of electronic alerts for hyponatraemia should be considered to improve clinical practice.

Incidence, Etiology and Outcomes of Hyponatremia after Transsphenoidal Surgery: Experience with 344 Consecutive Patients at a Single Tertiary Center

Hyponatremia is often seen after transsphenoidal surgery and is a source of considerable economic burden and patient-related morbidity and mortality. We performed a retrospective review of 344 patients who underwent transsphenoidal surgery at our institution between 2006 and 2012. Postoperative hyponatremia was seen in 18.0% of patients at a mean of 3.9 days postoperatively. Hyponatremia was most commonly mild (51.6%) and clinically asymptomatic (93.8%). SIADH was the primary cause of hyponatremia in the majority of cases (n = 44, 71.0%), followed by cerebral salt wasting (n = 15, 24.2%) and desmopressin over-administration (n = 3, 4.8%). The incidence of postoperative hyponatremia was significantly higher in patients with cardiac, renal and/or thyroid disease (p = 0.0034, Objective Risk (OR) = 2.60) and in female patients (p = 0.011, OR = 2.18) or patients undergoing post-operative cerebrospinal fluid drainage (p = 0.0006). Treatment with hypertonic saline (OR = −2.4, p = 0.10) and sodium chloride tablets (OR = −1.57, p = 0.45) was associated with a non-significant trend toward faster resolution of hyponatremia. The use of fluid restriction and diuretics should be de-emphasized in the treatment of post-transsphenoidal hyponatremia, as they have not been shown to significantly alter the time-course to the restoration of sodium balance.

Prognosis of hyponatremia in elderly patients with fragility fractures

BACKGROUND

Hyponatremia (serum sodium < 135 mmol/L) is the commonest electrolyte imbalance encountered in clinical practice. It is associated with multiple poor clinical outcomes including increased length of hospital stay, institutionalization and mortality. Prevalence of hyponatremia is higher in frail patient groups, and elderly patients with fragility fractures (EPFF) are particularly susceptible. This study aimed to establish the impact of hyponatremia on total length of inpatient stay (TLOS), need for inpatient rehabilitation and mortality in EPFF.

METHODS

Prospective observational study of consenting adults aged ≥ 65 years admitted with a fragility fracture to a university hospital between January 7, and April 4, 2013. Demographic and clinical data, length of hospital stay, discharge destination and any participant deaths were recorded. Prevalence of hyponatremia on admission and incidence of cases developing in hospital were reported. Basic demographic data and serum sodium results were included in multivariate linear regression models for TLOS. Difference in mortality rate and proportion of individuals discharged to inpatient rehabilitation between the hyponatremic and normonatremic group were tested using Chi-squared and Fisher's exact tests. Unadjusted odds ratios (ORs) and 95% confidence intervals (CIs) were also calculated.

RESULTS

Of 212 cases, 127 (60%) EPFF were recruited (mean age 79 years, 78% female). Of those not recruited, 66 had incapacity to consent and 19 refused participation. Thirty-three cases of hyponatremia were identified; point prevalence on admission was 13.4% and a further 12.6% developed hyponatremia during admission. There were no statistically significant differences in patient characteristics between the hyponatremic and normonatremic group. Hyponatremic participants had a 66.7% increased time from admission to surgery (P = 0.014) and a 51.5% increased length of index hospital stay (P = 0.006). Factors independently associated with increased TLOS were age (P = 0.03) and drop in sodium during admission (P < 0.001). Mortality rate and proportion of participants discharged to inpatient rehabilitation were higher in the hyponatremic group (OR 4.2 (95% CI: 0.9 - 19.8) and 2.2 (95% CI: 0.9 - 5.1), respectively), but figures did not reach statistical significance.

CONCLUSIONS

Hyponatremia is highly prevalent in EPFF, seen in 33/127 cases (26%), and is associated with increased length of index hospital stay. Drop in serum sodium during admission was independently associated with increased TLOS.

A case-control study of hyponatraemia as an independent risk factor for inpatient mortality

OBJECTIVES

Hyponatraemia is strongly associated with increased inpatient mortality, but it is unknown whether hyponatraemia per se contributes to excess mortality. Our hypothesis was that if hyponatraemic patients had significantly greater mortality compared with controls despite no difference with regard to gender, age, comorbidities and type of primary pathology, this would incriminate hyponatraemia as an independent predictor of mortality.

DESIGN

Single-centre, case-control study.

PATIENTS

Cases (N = 139) were hospitalized patients with serum Na ≤ 128 mmol/l over 3 months. Controls were 254 age- and gender-matched patients residing in the same hospital ward with serum Na > 128 mmol/l.

MEASUREMENTS

Data were collected about age, gender, comorbidities, drug history, serum creatinine, intensive care unit (ICU) admission and length of hospitalization. The main outcome measure was inpatient mortality.

RESULTS

Hyponatraemic patients had an inpatient mortality rate of 17·3% and were more than three times more likely to die during their hospital stay compared with controls (OR 3·33, 95% CI 1·68-6·58, P < 0·01) despite no statistically significant difference with respect to age, gender, comorbidities, use of common drugs, serum creatinine, ICU admission rate and length of hospitalization. Comparison of cases with the normonatraemic subgroup of controls demonstrated that cases were almost 12 times more likely to die during admission than normonatraemic controls (OR 11·89, 95% CI 2·75-51·51, P < 0·01).

CONCLUSIONS

This study showed that hyponatraemia is an independent predictor of mortality, and hyponatraemia per se is likely to contribute to excess mortality. Further studies are needed to examine whether correction of hyponatraemia can reduce mortality.

Management of hyponatraemia in older people: old threats and new opportunities

Hyponatraemia is the commonest electrolyte abnormality seen in clinical practice, and is especially prevalent in frail, older people. However, the serious implications of hyponatraemia in this age group are seldom recognized by clinicians. Hyponatraemia is associated with osteoporosis, impaired balance, falls, hip fractures and cognitive dysfunction. Even mild, apparently asymptomatic hyponatraemia is associated with prolonged stays in hospital, institutionalization and increased risk of death. Emerging evidence of the potential benefits of improved treatment of hyponatraemia is slowly generating renewed clinical interest in this area. The development of specific vasopressin-2 receptor antagonists (vaptans) has the potential to revolutionize the management of hyponatraemia, in particular for the syndrome of inappropriate antidiuretic hormone. However, challenges remain for the attending physician. Diagnosing the cause or causes of hyponatraemia in older people is difficult, and incorrect diagnosis can lead to treatment that worsens the electrolyte imbalance. Established treatments are often poorly tolerated and patient outcomes remain poor, and the role of vaptans in the treatment of older people is unclear. This review summarizes the existing evidence base and highlights areas of controversy. It includes practical guidance for overcoming some common pitfalls in the management of the elderly patient with hyponatraemia.

Characteristics, therapies, and factors influencing outcomes of hospitalized hypernatremic geriatric patients

PURPOSE

Hypernatremia is a common electrolyte disorder associated with adverse outcomes such as increased length of stay and mortality due to a variety of factors. Our aim was to investigate known factors as well as other variables which we had identified in hospitalized hypernatremic geriatric patients and their relationship to patient outcomes.

METHODS

A retrospective chart review of all adult hospitalized patients in a 4-month period with a serum sodium level >150 mmol/L was performed. Factors evaluated included use of a nephrology consultation, certain urine laboratory measures, fluids employed, rate of correction, and patient's level of care setting. Outcome measures included length of stay and mortality.

RESULTS

The patient mortality rate was 52 %. Mean age was 79.6 years (n = 33), and mean initial sodium level was 152.6 mmol/L. Plasma and urine osmolality, and urine sodium concentration were checked in less than 25 % of patients. Fifteen of 18 patients in the ICU expired, whereas only 2 of 15 patients not in the ICU expired (p < 0.0004, OR 32.50, CI 95 % (4.68-225.54)). Of the 23 patients (70 %) who had their serum sodium level corrected, 11 were corrected in ≤3 days and 12 in >3 days, but this difference did not affect mortality rate (45 vs. 50 %, p = 0.99). The mortality rate was similar (60 %, p = 0.52) for those whose serum sodium level never corrected suggesting that correction did not influence outcomes. The fluids chosen for therapy of the hypernatremia were appropriate to the patients volume status. Five of 15 patients who received a nephrology consultation survived, while 11 of 18 patients without a nephrology consultation survived (p = 0.12). The mean length of stay was 25.0 ± 23.9 days and no different for those who expired versus those who survived (25.2 ± 21.2 vs. 24.8 ± 25.9 days, p = 0.96).

CONCLUSIONS

Hypernatremia is associated with a poor prognosis, and outcomes are still disappointing despite appropriate rates of correction, intensive monitoring, and the involvement of a nephrologist. Strategies directed at avoidance of the development of hypernatremia and attention to concomitant disease may provide significant patient benefit.

[Hormonal dysnatremia]

Because of antidiuretic hormone (ADH) disorder on production or function we can observe dysnatremia. In the absence of production by posterior pituitary, central diabetes insipidus (DI) occurs with hypernatremia. There are hereditary autosomal dominant, autosomal recessive or X- linked forms. When ADH is secreted but there is an alteration on his receptor AVPR2, it is a nephrogenic diabetes insipidus in acquired or hereditary form. We can make difference on AVP levels and/or on desmopressine response which is negative in nephrogenic forms. Hyponatremia occurs when there is an excess of ADH production: it is a euvolemic hypoosmolar hyponatremia. The most frequent etiology is SIADH (syndrome of inappropriate secretion of ADH), a diagnostic of exclusion which is made after eliminating corticotropin deficiency and hypothyroidism. In case of brain injury the differential diagnosis of cerebral salt wasting (CSW) syndrome has to be discussed, because its treatment is perfusion of isotonic saline whereas in SIADH, the treatment consists in administration of hypertonic saline if hyponatremia is acute and/or severe. If not, fluid restriction demeclocycline or vaptans (antagonists of V2 receptors) can be used in some European countries. Four types of SIADH exist; 10 % of cases represent not SIADH but SIAD (syndrome of inappropriate antidiuresis) due to a constitutive activation of vasopressin receptor that produces water excess. c 2013 Published by Elsevier Masson SAS.

Awareness and management of hyponatraemia: the Italian Hyponatraemia Survey

BACKGROUND

Hyponatraemia is the most frequent electrolyte disorder in hospitalized patients and has been associated with increased morbidity, mortality and length of hospital stay. There is evidence that also mild chronic hyponatraemia may have clinical consequences, such as gait disturbances, attention deficits, falls, increased risk of fractures and reduced bone mineral density. Nevertheless, this condition appears to be rather often not taken into consideration, or inappropriately managed and treated, thus negatively affecting patients' outcome.

AIM

The aim of this study was to investigate the awareness and management of hyponatraemia secondary to SIAD, a common cause of hyponatraemia, among Italian physicians (endocrinologists, nephrologists, internists) commonly involved as consultants.

METHODS

A questionnaire, covering definition, diagnosis, management, treatment and prognosis of hyponatraemia secondary to SIAD, was developed with the support of the Italian Society of Endocrinology.

RESULTS

Among the respondents (n=275), the majority was aware of the negative implications of hyponatraemia or of an inappropriate treatment. Nevertheless, the answers indicated that SIAD is still underdiagnosed and incorrectly managed in clinical practice. In particular, only 47% of respondents used the validated biochemical parameters to diagnose hyponatraemia secondary to SIAD. The survey also indicated a rather satisfactory knowledge of the therapeutic options, including the currently available vasopressin receptor antagonists.

CONCLUSIONS

One of the main findings of the survey was that the diagnostic work-up of hyponatraemia still represents a critical issue. Therefore, there is urgent need of educational programs in order to improve the management of this condition and reduce morbidity, mortality and costs.

Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations

Hyponatremia is a serious, but often overlooked, electrolyte imbalance that has been independently associated with a wide range of deleterious changes involving many different body systems. Untreated acute hyponatremia can cause substantial morbidity and mortality as a result of osmotically induced cerebral edema, and excessively rapid correction of chronic hyponatremia can cause severe neurologic impairment and death as a result of osmotic demyelination. The diverse etiologies and comorbidities associated with hyponatremia pose substantial challenges in managing this disorder. In 2007, a panel of experts in hyponatremia convened to develop the Hyponatremia Treatment Guidelines 2007: Expert Panel Recommendations that defined strategies for clinicians caring for patients with hyponatremia. In the 6 years since the publication of that document, the field has seen several notable developments, including new evidence on morbidities and complications associated with hyponatremia, the importance of treating mild to moderate hyponatremia, and the efficacy and safety of vasopressin receptor antagonist therapy for hyponatremic patients. Therefore, additional guidance was deemed necessary and a panel of hyponatremia experts (which included all of the original panel members) was convened to update the previous recommendations for optimal current management of this disorder. The updated expert panel recommendations in this document represent recommended approaches for multiple etiologies of hyponatremia that are based on both consensus opinions of experts in hyponatremia and the most recent published data in this field.

Epidemiology and characteristics of hyponatremia in the emergency department

BACKGROUND

Hyponatremia is the most common electrolyte abnormality and it is associated with increased morbidity and mortality. The aim of the study was to investigate the underlying causes and management of hyponatremia in an unselected population presenting with hyponatremia to the emergency department.

METHODS

A descriptive, retrospective hospital record study was performed. A database search was conducted for all patients presenting to the emergency departments in Lund and Malmo and patients with a P-Na-value<135mmol/L were identified. Patients were divided into four groups based on the severity of hyponatremia (Group 1: P-Na<120mM, Group 2: Na 120-124mM, Group 3: Na 125-129mM, Group 4: Na 130-134mM) and 100 patients from each group were included. Groups 2-4 were matched to Group 1 for age, gender and month for ER visit.

RESULTS

The prevalence of hyponatremia (P-Na<135mmol/L) was 3% in the entire emergency population. A single underlying cause was identified in 45% of patients in Group 1. The leading aetiologies were thiazide diuretics (17%), SIADH (17%) and other diuretics (14%). The likelihood of being on thiazide diuretics increased with hyponatremia severity (p<0.0001) and patients in Group 1 were 3.6 times (CI95%:1.9-6.8) more likely to be on thiazide diuretics compared to Group 4. The in-hospital mortality ranged between 2 and 7% between the groups (NS). One patient developed osmotic demyelinisation syndrome but survived. Only 31% of patients in Group 1 were evaluated with a basic laboratory investigation.

CONCLUSIONS

Thiazide diuretics and SIADH were dominating underlying causes of hyponatremia, however, the frequency of adequate diagnostic testing was low. The majority of patients were treated with sodium chloride infusion.

Clinical review: practical approach to hyponatraemia and hypernatraemia in critically ill patients

Disturbances in sodium concentration are common in the critically ill patient and associated with increased mortality. The key principle in treatment and prevention is that plasma [Na+] (P-[Na+]) is determined by external water and cation balances. P-[Na+] determines plasma tonicity. An important exception is hyperglycaemia, where P-[Na+] may be reduced despite plasma hypertonicity. The patient is first treated to secure airway, breathing and circulation to diminish secondary organ damage. Symptoms are critical when handling a patient with hyponatraemia. Severe symptoms are treated with 2 ml/kg 3% NaCl bolus infusions irrespective of the supposed duration of hyponatraemia. The goal is to reduce cerebral symptoms. The bolus therapy ensures an immediate and controllable rise in P-[Na+]. A maximum of three boluses are given (increases P-[Na+] about 6 mmol/l). In all patients with hyponatraemia, correction above 10 mmol/l/day must be avoided to reduce the risk of osmotic demyelination. Practical measures for handling a rapid rise in P-[Na+] are discussed. The risk of overcorrection is associated with the mechanisms that cause hyponatraemia. Traditional classifications according to volume status are notoriously difficult to handle in clinical practice. Moreover, multiple combined mechanisms are common. More than one mechanism must therefore be considered for safe and lasting correction. Hypernatraemia is less common than hyponatraemia, but implies that the patient is more ill and has a worse prognosis. A practical approach includes treatment of the underlying diseases and restoration of the distorted water and salt balances. Multiple combined mechanisms are common and must be searched for. Importantly, hypernatraemia is not only a matter of water deficit, and treatment of the critically ill patient with an accumulated fluid balance of 20 litres and corresponding weight gain should not comprise more water, but measures to invoke a negative cation balance. Reduction of hypernatraemia/hypertonicity is critical, but should not exceed 12 mmol/l/day in order to reduce the risk of rebounding brain oedema.