Risk Factors and Outcomes of Rapid Correction of Severe Hyponatremia

Severe Hyponatremia (96 mmol/L) Secondary to Primary Polydipsia and Pneumonia

A 63-year-old man who presented to the hospital with altered mental status and decreased responsiveness was found to have severe symptomatic hyponatremia with a sodium level of 96 mmol/L and pneumonia. The patient was admitted to the medical intensive care unit for septic shock and acute severe hyponatremia. He was intubated for airway protection, and treated with 3% hypertonic saline bolus and antibiotics. After four days, sodium levels were corrected to 128 mmol/L, and the patient was extubated and downgraded to the medical floor. This case demonstrates one of the lowest recorded sodium lab values ever and the patient was successfully treated and discharged home with appropriate outpatient appointments.

An appraisal of the practice of duplicate testing for the detection of irregular analytical errors

OBJECTIVES

Our study aimed to determine the usefulness of duplicate testing in identifying irregular analytical errors and subsequent prevention of patient mismanagement.

METHODS

In our laboratory, all requests for Na+, Ca2+, alkaline phosphatase (ALP), and high-sensitivity cardiac-troponin-I (hs-cTnI) are run in duplicate. Data from four separate weeks for Na+ (n=21,649), Ca2+ (n=14,803) and ALP (n=19,698); and a full year for hs-cTnI (n=17,036) were gathered. For each test, pre-defined limits for differences between duplicates were used to identify erroneous results (Fliers). We further characterised a subset of such fliers as "critical errors", where duplicates fell on opposing sides of a reference/decision making threshold. The costs/benefits of running these tests in duplicate were then considered in light of increased number of tests analysed by this approach.

RESULTS

For Na+, 0.03 % of duplicates met our flier defining criteria, and 0.01 % of specimens were considered critical errors. For Ca2+ requests, 4.58 % of results met our flier defining criteria and 0.84 % were critical errors. For ALP, 0.22 % of results were fliers, and 0.01 % were critical errors. For hs-cTnI, 1.58 % of results were classified as fliers, whilst 0.14 % were classified as a critical error. Depending on the test in question, running all analyses in duplicate increased annual costs by as little as €1,100 (for sodium), and as much as €48,000 (for hs-cTnI).

CONCLUSIONS

Duplicate testing is effective at identifying and mitigating irregular laboratory errors, and is best suited for assays predisposed to such error, where costs are minimal, and clinical significance of an incorrect result can justify the practice.

Hyponatremia in the Context of Liver Disease

Hyponatremia is common in patients with liver disease and is associated with increased mortality, morbidity, and a reduced quality of life. In liver transplantation, the inclusion of hyponatremia in organ allocation scores has reduced waitlist mortality. Portal hypertension and the resulting lowering of the effective arterial blood volume are important pathogenetic factors, but in most patients with liver disease, hyponatremia is multifactorial. Treatment requires a multifaceted approach that tries to reduce electrolyte-free water intake, restore urinary dilution, and increase nonelectrolyte solute excretion. Albumin therapy for hyponatremia is a peculiarity of advanced liver disease. Its use appears to be increasing, while the vaptans are currently only given in selected cases. Osmotic demyelination is a special concern in patients with liver disease. Serial checks of serum sodium concentrations and urine volume monitoring are mandatory.

[Dysnatremias - concepts and clinical work-up]

Osmotic gradients over cell membranes lead to water movement into or out of cells. An intact osmoregulation prevents osmotic gradients, thereby protecting cells from swelling or shrinking. Na+ is the major cation in the extracellular fluid (ECF) and the major determinant of the osmolarity in the ECF, including plasma. Therefore, the plasma-Na+ concentration needs to be tightly regulated. An excess of electrolyte-free water decreases the concentration of osmolytes leading to hyponatremia. In contrast, a free water deficit increases the osmolyte concentration leading to hypernatremia. Pathophysiology-oriented approaches to dysnatremic patients help both clinicians and patients. Therapeutic interventions depend on the differentiation between acute and chronic, asymptomatic, and symptomatic dysnatremia, and on the patient's extracellular volume status. The therapeutic armamentarium for hyponatremia consists of water restriction, hypertonic infusions, urea, V2 receptor-blockers, and sodium-glucose cotransporter 2 (SGLT2) inhibitors. Patients with hypernatremia are treated with electrolyte-free water or hypotonic sodium-containing solutions depending on their volume status. Basic concepts in the management of dysnatremic patients are discussed.

[Consensus recommendations on the diagnosis and treatment of hyponatremia from the Austrian Society for Nephrology 2024]

Hyponatremia is a disorder of water homeostasis. Water balance is maintained by the collaboration of renal function and cerebral structures, which regulate thirst mechanisms and secretion of the antidiuretic hormone. Measurement of serum-osmolality, urine osmolality and urine-sodium concentration help to diagnose the different reasons for hyponatremia. Hyponatremia induces cerebral edema and might lead to severe neurological symptoms, which need acute therapy. Also, mild forms of hyponatremia should be treated causally, or at least symptomatically. An inadequate fast increase of the serum sodium level should be avoided, because it raises the risk of cerebral osmotic demyelination. Basic pathophysiological knowledge is necessary to identify the different reasons for hyponatremia which need different therapeutic procedures.

Treatment Guidelines for Hyponatremia: Stay the Course

International guidelines designed to minimize the risk of complications that can occur when correcting severe hyponatremia have been widely accepted for a decade. On the basis of the results of a recent large retrospective study of patients hospitalized with hyponatremia, it has been suggested that hyponatremia guidelines have gone too far in limiting the rate of rise of the serum sodium concentration; the need for therapeutic caution and frequent monitoring of the serum sodium concentration has been questioned. These assertions are reminiscent of a controversy that began many years ago. After reviewing the history of that controversy, the evidence supporting the guidelines, and the validity of data challenging them, we conclude that current safeguards should not be abandoned. To do so would be akin to discarding your umbrella because you remained dry in a rainstorm. The authors of this review, who represent 20 medical centers in nine countries, have all contributed significantly to the literature on the subject. We urge clinicians to continue to treat severe hyponatremia cautiously and to wait for better evidence before adopting less stringent therapeutic limits.

Osmotic Demyelination Syndrome in a High-Risk Patient Despite Cautious Correction of Hyponatremia

Hyponatremia is a common electrolyte disorder requiring careful management to prevent severe complications. Osmotic demyelination syndrome (ODS) is a serious neurological disorder that can develop from rapid correction of hyponatremia. Herein, is a description of the case of a 61-year-old man with multiple risk factors, including alcoholism, hypokalemia, malnutrition, and alcoholic liver cirrhosis, who developed ODS despite adherence to the recommended correction rate for hyponatremia. The patient presented to the emergency department with generalized weakness, gait disturbance, and decreased muscle strength. Initial laboratory investigations revealed severe hyponatremia, hypokalemia, and dehydration. The patient was treated with cautious correction of the hyponatremia below 8 mmol/L per day. However, on the seventh hospital day, he developed tremors, rigidity, and decreased consciousness and was diagnosed with osmotic demyelination syndrome. Despite receiving general supportive care, desmopressin, and dextrose 5% in water to reduce the serum sodium levels, the patient did not show significant improvement and was transferred to a nursing home for long-term conservative care on day 35 of hospitalization. This case report highlights the challenges associated with the diagnosis and management of osmotic demyelination syndrome and the importance of identifying patients at high risk of developing this neurological disorder.

Thalamic Neuron Resilience during Osmotic Demyelination Syndrome (ODS) Is Revealed by Primary Cilium Outgrowth and ADP-ribosylation factor-like protein 13B Labeling in Axon Initial Segment

A murine osmotic demyelinating syndrome (ODS) model was developed through chronic hyponatremia, induced by desmopressin subcutaneous implants, followed by precipitous sodium restoration. The thalamic ventral posterolateral (VPL) and ventral posteromedial (VPM) relay nuclei were the most demyelinated regions where neuroglial damage could be evidenced without immune response. This report showed that following chronic hyponatremia, 12 h and 48 h time lapses after rebalancing osmolarity, amid the ODS-degraded outskirts, some resilient neuronal cell bodies built up primary cilium and axon hillock regions that extended into axon initial segments (AIS) where ADP-ribosylation factor-like protein 13B (ARL13B)-immunolabeled rod-like shape content was revealed. These AIS-labeled shaft lengths appeared proportional with the distance of neuronal cell bodies away from the ODS damaged epicenter and time lapses after correction of hyponatremia. Fine structure examination verified these neuron abundant transcriptions and translation regions marked by the ARL13B labeling associated with cell neurotubules and their complex cytoskeletal macromolecular architecture. This necessitated energetic transport to organize and restore those AIS away from the damaged ODS core demyelinated zone in the murine model. These labeled structures could substantiate how thalamic neuron resilience occurred as possible steps of a healing course out of ODS.

Diagnostic and Therapeutic Strategies to Severe Hyponatremia in the Intensive Care Unit

Hyponatremia is the most common electrolyte abnormality encountered in critically ill patients and is linked to heightened morbidity, mortality, and healthcare resource utilization. However, its causal role in these poor outcomes and the impact of treatment remain unclear. Plasma sodium is the main determinant of plasma tonicity; consequently, hyponatremia commonly indicates hypotonicity but can also occur in conjunction with isotonicity and hypertonicity. Plasma sodium is a function of total body exchangeable sodium and potassium and total body water. Hypotonic hyponatremia arises when total body water is proportionally greater than the sum of total body exchangeable cations, that is, electrolyte-free water excess; the latter is the result of increased intake or decreased (kidney) excretion. Hypotonic hyponatremia leads to water movement into brain cells resulting in cerebral edema. Brain cells adapt by eliminating solutes, a process that is largely completed by 48 h. Clinical manifestations of hyponatremia depend on its biochemical severity and duration. Symptoms of hyponatremia are more pronounced with acute hyponatremia where brain adaptation is incomplete while they are less prominent in chronic hyponatremia. The authors recommend a physiological approach to determine if hyponatremia is hypotonic, if it is mediated by arginine vasopressin, and if arginine vasopressin secretion is physiologically appropriate. The treatment of hyponatremia depends on the presence and severity of symptoms. Brain herniation is a concern when severe symptoms are present, and current guidelines recommend immediate treatment with hypertonic saline. In the absence of significant symptoms, the concern is neurologic sequelae resulting from rapid correction of hyponatremia which is usually the result of a large water diuresis. Some studies have found desmopressin useful to effectively curtail the water diuresis responsible for rapid correction.

An Exchange about "Osmotic Demyelination Syndrome in Patients Hospitalized with Hyponatremia"

In Volume 2, Number 4 of NEJM Evidence, we published an article entitled, "Osmotic Demyelination Syndrome in Patients Hospitalized with Hyponatremia" by MacMillan et al. The article was accompanied by an editorial entitled "Hyponatremia Treatment Guidelines - Have They Gone Too Far?" by Ayus and Moritz. After these articles were published, a group of readers shared feedback about the data presented and the conclusions drawn; their comments are detailed as "Remarks from Readers." We relayed these points to the authors of the original article and the editorial; their responses follow.

Effects of correction rate for severe hyponatremia in the intensive care unit on patient outcomes

PURPOSE

Limited evidence exists regarding outcomes associated with different correction rates of severe hyponatremia.

MATERIALS AND METHODS

This retrospective cohort analysis employed a multi-center ICU database to identify patients with sodium ≤120 mEq/L during ICU admission. We determined correction rates over the first 24 h and categorized them as rapid (> 8 mEq/L/day) or slow (≤ 8 mEq/L/day). The primary outcome was in-hospital mortality. Secondary outcomes included hospital-free days, ICU-free days, and neurological complications. We used inverse probability weighting for confounder adjustment.

RESULTS

Our cohort included 1024 patients; 451 rapid and 573 slow correctors. Rapid correction was associated with lower in-hospital mortality (absolute difference: -4.37%; 95% CI, -8.47 to -0.26%), longer hospital-free days (1.80 days; 95% CI, 0.82 to 2.79 days), and longer ICU-free days (1.16 days; 95% CI, 0.15 to 2.17 days). There was no significant difference in neurological complications (2.31%; 95% CI, -0.77 to 5.40%).

CONCLUSION

Rapid correction (>8 mEq/L/day) of severe hyponatremia within the first 24 h was associated with lower in-hospital mortality and longer ICU and hospital-free days without an increase in neurological complication. Despite major limitations, including the inability to identify the chronicity of hyponatremia, the results have important implications and warrant prospective studies.

Severe Hyponatremia Correction, Mortality, and Central Pontine Myelinolysis

BACKGROUND: In clinical practice, sodium correction rates are frequently limited in patients with severe hyponatremia to prevent neurologic complications. The implications of correction rates on overall mortality and length of hospital stay are unclear. METHODS: In this multicenter observational study, we evaluated the association of sodium correction rates with mortality, length of stay, and central pontine myelinolysis (CPM) in patients hospitalized with severe hyponatremia (admission serum sodium level less than 120 mEq/l). RESULTS: The cohort included 3274 patients. A correction rate of less than 6 mEq/l/24 hours was observed in 38%, 6 to 10 mEq/l/24 hours was observed in 29%, and greater than 10 mEq/l/24 hours was observed in 33%. Compared with 6 to 10 mEq/l/24 hours, a correction rate of less than 6 mEq/l/24 hours exhibited higher in-hospital mortality in multivariable-adjusted and propensity score–weighted analyses. Compared with 6 to 10 mEq/l/24 hours, a correction rate of greater than 10 mEq/l/24 hours was associated with lower in-hospital mortality and shorter length of stay in multivariable analyses. Seven patients with CPM were identified, with five of seven developing CPM despite a sodium correction rate of less than or equal to 8 mEq/l/24 hours. Six of seven patients who developed CPM had alcohol use disorder, malnutrition, hypokalemia, or hypophosphatemia. CONCLUSIONS: Limiting the sodium correction rate was associated with higher mortality and longer length of stay. Whether the sodium correction rate influences neurologic complications needs further evaluation.

Syndrome of Inappropriate Antidiuresis: From Pathophysiology to Management

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

Loss of Ephaptic Contacts in the Murine Thalamus during Osmotic Demyelination Syndrome

BACKGROUND AND AIM

A murine model mimicking osmotic demyelination syndrome (ODS) revealed with histology in the relay posterolateral (VPL) and ventral posteromedial (VPM) thalamic nuclei adjoined nerve cell bodies in chronic hyponatremia, amongst the damaged 12 h and 48 h after reinstatement of osmolality. This report aims to verify and complement with ultrastructure other neurophysiology, immunohistochemistry, and molecular biochemistry data to assess the connexin-36 protein, as part of those hinted close contacts.This ODS investigation included four groups of mice: Sham (NN; n = 13), hyponatremic (HN; n = 11), those sacrificed 12 h after a fast restoration of normal natremia (ODS12h; n = 6) and mice sacrificed 48 h afterward, or ODS48 h (n = 9). Out of these, thalamic zones samples included NN (n = 2), HN (n = 2), ODS12h (n = 3) and ODS48h (n = 3).

RESULTS

Ultrastructure illustrated junctions between nerve cell bodies that were immunolabeled with connexin36 (Cx36) with light microscopy and Western blots. These cell's junctions were reminiscent of low resistance junctions characterized in other regions of the CNS with electrophysiology. Contiguous neurons showed neurolemma contacts in intact and damaged tissues according to their location in the ODS zones, at 12 h and 48 h post correction along with other demyelinating alterations. Neurons and ephaptic contact measurements indicated the highest alterations, including nerve cell necrosis in the ODS epicenter and damages decreased toward the outskirts of the demyelinated zone.

CONCLUSION

Ephapses contained C × 36between intact or ODS injured neurons in the thalamus appeared to be resilient beyond the core degraded tissue injuries. These could maintain intercellular ionic and metabolite exchanges between these lesser injured regions and, thus, would partake to some brain plasticity repairs.

[Hyponatremia : Etiology, diagnosis and acute therapy]

Hyponatremia is one of the most common electrolyte disorders in emergency departments and hospitalized patients. Serum sodium concentration is controlled by osmoregulation and volume regulation. Both pathways are regulated via the release of antidiuretic hormone (ADH). Syndrome of inappropriate release of ADH (SIADH) may be caused by neoplasms or pneumonia but may also be triggered by drug use or drug abuse. Excessive fluid intake may also result in a decrease in serum sodium concentration. Rapid alteration in serum sodium concentration leads to cell swelling or cell shrinkage, which primarily causes neurological symptoms. The dynamics of development of hyponatremia and its duration are crucial. In addition to blood testing, a clinical examination and urine analysis are essential in the differential diagnosis of hyponatremia.

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.

Hyponatremia Treatment Guidelines - Have They Gone Too Far?

Hyponatremia is a common electrolyte abnormality affecting hospitalized patients.1 It is an independent predictor for mortality and is associated with increased length of hospital stay and higher costs. The most serious potential complication is hyponatremic encephalopathy, a medical emergency that can result in death or irreversible brain injury if inadequately treated.2 Hypertonic saline is a safe and effective means of correcting hyponatremia.2-4 A rare yet serious complication from excessive correction of chronic hyponatremia is the development of cerebral demyelination.

Osmotic Demyelination Syndrome in Patients Hospitalized with Hyponatremia

BACKGROUND: Osmotic demyelination syndrome (ODS) is a rare but potentially devastating neurologic complication of hyponatremia. The primary objective of this study was to identify the proportion of patients who developed ODS in a large, contemporary, multicenter cohort of patients admitted to the hospital with hyponatremia. METHODS: We conducted a multicenter cohort study of patients admitted with hyponatremia at five academic hospitals in Toronto, Ontario, Canada, between April 1, 2010, and December 31, 2020. All adult patients presenting with hyponatremia (serum sodium level 8 mmol/l in any 24-hour period). RESULTS: Our cohort included 22,858 hospitalizations with hyponatremia. Approximately 50% were women, the average age was 68 years, and mean initial serum sodium was 125 mmol/l (standard deviation, 4.6), including 11.9% with serum sodium from 110 to 119 mmol/l and 1.2% with serum sodium less than 110 mmol/l. Overall, rapid correction of serum sodium occurred in 3632 (17.7%) admissions. Twelve patients developed ODS (0.05%). Seven (58%) patients who developed ODS did not have rapid correction of serum sodium. CONCLUSIONS: In this large multicenter study of patients with hyponatremia, rapid correction of serum sodium was common (n=3632 [17.7%]), but ODS was rare (n=12 [0.05%]). Future studies with a higher number of patients with ODS are needed to better understand potential causal factors for ODS.

[Dysnatremia]

Changes in serum sodium concentrations are frequently encountered by anesthesiologists, are complex and are often inadequately treated. Feared consequences include neurological complications, such as cerebral hemorrhage, cerebral edema and coma. Dysnatremia is always accompanied disturbances in the water balance. Accordingly, these are routinely classified based on the tonicity; however, in the daily routine and especially in the acute setting, the volume status and extracellular volume are often difficult to assess. Severe symptomatic hyponatremia with impending cerebral edema is treated by administration of hypertonic saline solution. If the rise in serum sodium is too rapid, there is a risk of central pontine myelinolysis. In a second step, the cause of the hyponatremia can be investigated and the appropriate treatment can be initiated. In the case of hypernatremia, the etiology of the disorder must be clarified before treatment. The goal is to compensate for the water deficiency by correcting the cause, specific volume therapy and, if necessary, drug support. A slow and controlled compensation must be closely monitored in order to avoid neurological complications. An algorithm has been developed that provides an overview of the dysnatremias, aids with making the diagnosis and gives recommendations for treatment measures in the clinical routine.

Overcorrection and undercorrection with fixed dosing of bolus hypertonic saline for symptomatic hyponatremia

OBJECTIVE

Current guidelines recommend treating symptomatic hyponatremia with rapid bolus-wise infusion of fixed volumes of hypertonic saline regardless of body weight. We hypothesize that this approach is associated with overcorrection and undercorrection in patients with low and high body weight.

DESIGN

Single-center, retrospective cohort study.

METHODS

Data were collected on patients treated with ≥1 bolus 100 or 150 mL 3% NaCl for symptomatic hyponatremia between 2017 and 2021. Outcomes were overcorrection (plasma sodium rise > 10 mmol/L/24 h, > 18 mmol/L/48 h, or relowering therapy) and undercorrection (plasma sodium rise < 5 mmol/L/24 h). Low body weight and high body weight were defined according to the lowest (≤60 kg) and highest (≥80 kg) quartiles.

RESULTS

Hypertonic saline was administered to 180 patients and caused plasma sodium to rise from 120 mmol/L to 126.4 mmol/L (24 h) and 130.4 mmol/L (48 h). Overcorrection occurred in 32 patients (18%) and was independently associated with lower body weight, weight ≤ 60 kg, lower baseline plasma sodium, volume depletion, hypokalemia, and less boluses. In patients without rapidly reversible causes of hyponatremia, overcorrection still occurred more often in patients ≤ 60 kg. Undercorrection occurred in 52 patients (29%) and was not associated with body weight or weight ≥ 80 kg but was associated with weight ≥ 100 kg and lean body weight in patients with obesity.

CONCLUSION

Our real-world data suggest that fixed dosing of bolus hypertonic saline may expose patients with low and high body weight to more overcorrection and undercorrection, respectively. Prospective studies are needed to develop and validate individualized dosing models.

Pontine and bilateral cerebellar lesion in osmotic demyelination syndrome associated with uncontrolled type II diabetes mellitus: a case report

Osmotic demyelination syndrome (ODS) as a result of the hyperosmolar hyperglycemic state is rare and can present with variable neurological manifestation due to lysis of myelin sheath.

Case presentation

A 44-year diabetic male presented with complaints of sudden onset, progressive bilateral weakness in lower limbs, and slurring of speech for the past 1.5 months. Cerebellar examination showed a bilaterally impaired finger nose test, dysdiadochokinesia, impaired heel shin test, and an impaired tandem gait. MRI brain (T2 and fluid-attenuated inversion recovery sequences) showed high signal intensity in the central pons and bilateral cerebellum. With a diagnosis of ODS with poorly controlled diabetes, he was treated with insulin, metformin, and supportive measures following which his symptoms subsided gradually.

Clinical discussion

A rapid correction of hyponatremia is considered the most common cause of ODS. Variations in plasma glucose levels, a rare cause of ODS, can cause an abrupt osmolality change causing pontine and extrapontine myelinolysis. Prevention of rapid correction of hyponatremia and rapid changes in plasma osmolality in vulnerable patients is the mainstay of treatment.

Conclusions

Clinical features, imaging studies, and monitoring of serum osmolality, serum glucose, and electrolytes aid in diagnosis and favorable outcomes for the patient.

Clinical Approach to Euvolemic Hyponatremia

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

NaCl 3% bolus therapy as emergency treatment for severe hyponatremia: Comparison of 100 ml versus 250 ml

CONTEXT

The aim of initial treatment of severe hyponatremia is to rapidly increase serum sodium to reduce the complications of cerebral edema. The optimal strategy to achieve this goal safely is still under debate.

OBJECTIVE

To compare the efficacy and safety of 100 and 250 ml NaCl 3% rapid bolus therapy as initial treatment of severe hypotonic hyponatremia.

DESIGN

Retrospective analysis of patients admitted between 2017 and 2019.

SETTING

Teaching hospital in the Netherlands.

PATIENTS

130 adults with severe hypotonic hyponatremia, defined as serum sodium ≤ 120 mmol/L.

INTERVENTION

A bolus of either 100 ml (N = 63) or 250 ml (N = 67) NaCl 3% as initial treatment.

MAIN OUTCOME MEASURES

Successful treatment was defined as a rise in serum sodium ≥ 5 mmol/L within the first 4 hours after bolus therapy. Overcorrection of serum sodium was defined as an increase of more than 10 mmol/L in the first 24 hours.

RESULTS

The percentage of patients with a rise in serum sodium ≥ 5 mmol/L within 4 hours was 32% and 52% after a bolus of 100 and 250 ml, respectively (P=0.018). Overcorrection of serum sodium was observed after a median of 13 hours (range 9 - 17 hours) in 21% of patients in both treatment groups (P=0.971). Osmotic demyelination syndrome did not occur.

CONCLUSION

Initial treatment of severe hypotonic hyponatremia is more effective with a NaCl 3% bolus of 250 ml than of 100 ml and does not increase the risk of overcorrection.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Predictive correction of serum sodium concentration with formulas derived from the Edelman equation in patients with severe hyponatremia

Severe hyponatremia can cause life-threatening cerebral edema. Treatment comprises rapid elevation of serum sodium concentration; however, overcorrection can result in osmotic demyelination. This study investigated potential factors, including predictive correction based on the Edelman equation, associated with appropriate correction in 221 patients with a serum sodium concentration ≤ 120 mEq/L who were admitted to a hospital in Nagoya, Japan. Appropriate correction was defined as an elevation in serum sodium concentration in the range of 4-10 mEq/L in the first 24 h and within 18 mEq/L in the first 48 h after the start of the correction. Appropriate corrections were made in 132 (59.7%) of the 221 patients. Multivariate analysis revealed that predictive correction with an infusate and fluid loss formula derived from the Edelman equation was associated with appropriate correction of serum sodium concentration (adjusted odds ratio, 7.84; 95% confidence interval, 2.97-20.64). Relative without its use, the predictive equation results in a lower proportion of undercorrection (14.3% vs. 48.0%, respectively) and overcorrection (1.0% vs. 12.2%, respectively). These results suggest that predictive correction of serum sodium concentrations using the formula derived from the Edelman equation can play an essential role in the appropriate management of patients with severe hyponatremia.

Epidemiology and outcomes of hyponatremia in patients with COVID-19-A territory-wide study in Hong Kong

Background

Hyponatremia is common in COVID-19, but its epidemiology and impact on clinical outcomes in relation to different variants, especially the Omicron variant, requires further clarification.

Methods

This was a territory-wide retrospective study to investigate the epidemiology and outcomes of COVID-19 patients with hyponatremia from January 1, 2020 to March 31, 2022 in Hong Kong. The primary outcome was 30-day mortality of patients with COVID-19 and hyponatremia at presentation. Secondary outcomes included rate of hospitalization, intensive care unit (ICU) hospitalization, overall duration of hospitalization, and duration of ICU hospitalization.

Results

A total of 53,415 COVID-19 patients were included for analysis, of which 14,545 (27.2%) had hyponatremia at presentation. 9813 (67.5%), 2821 (19.4%), and 1911 (13.1%) had mild (130 to <135 mmol/L), moderate (125 to <130 mmol/L), and severe hyponatremia (<125 mmol/L) at presentation respectively. Age, male sex, diabetes, active malignancy, white cell count, serum creatinine, hypoalbuminemia, C-reactive protein, and viral loads were independent predictors for hyponatremia in COVID-19 patients (P < 0.001, for all). Hyponatremic patients had increased 30-day mortality (9.7 vs. 5.7%, P < 0.001), prolonged hospitalization (11.9 ± 15.1 days vs. 11.5 ± 12.1 days, P < 0.001), and more ICU admissions (7.0% vs. 3.3%, P < 0.001). Patients diagnosed during the "fifth wave" Omicron BA.2 outbreak had 2.29-fold risk (95% CI 2.02-2.59, P < 0.001) of presenting with hyponatremia compared to other waves.

Conclusion

Hyponatremia is common among COVID-19 patients, and may serve as a prognostic indicator for unfavorable outcomes and increased healthcare utilization in the evolving COVID-19 outbreak.

Safely correct hyponatremia with continuous renal replacement therapy: A flexible, all-purpose method based on the mixing paradigm

Treating chronic hyponatremia by continuous renal replacement therapy (CRRT) is challenging because the gradient between a replacement fluid's [sodium] and a patient's serum sodium can be steep, risking too rapid of a correction rate with possible consequences. Besides CRRT, other gains and losses of sodium- and potassium-containing solutions, like intravenous fluid and urine output, affect the correction of serum sodium over time, known as osmotherapy. The way these fluids interact and contribute to the sodium/potassium/water balance can be parsed as a mixing problem. As Na/K/H₂ O are added, mixed in the body, and drained via CRRT, the net balance of solutes must be related to the change in serum sodium, expressible as a differential equation. Its solution has many variables, one of which is the sodium correction rate, but all variables can be evaluated by a root-finding technique. The mixing paradigm is proved to replicate the established equations of osmotherapy, as in the special case of a steady volume. The flexibility to solve for any variable broadens our treatment options. If the pre-filter replacement fluid cannot be diluted, then we can compensate by calculating the CRRT blood flow rate needed. Or we can deduce the infusion rate of dextrose 5% water, post-filter, to appropriately slow the rise in serum sodium. In conclusion, the mixing model is a generalizable and practical tool to analyze patient scenarios of greater complexity than before, to help doctors customize a CRRT prescription to safely and effectively reach the serum sodium target.

Diagnosis and Management of Hyponatremia: A Review

IMPORTANCE

Hyponatremia is the most common electrolyte disorder and it affects approximately 5% of adults and 35% of hospitalized patients. Hyponatremia is defined by a serum sodium level of less than 135 mEq/L and most commonly results from water retention. Even mild hyponatremia is associated with increased hospital stay and mortality.

OBSERVATIONS

Symptoms and signs of hyponatremia range from mild and nonspecific (such as weakness or nausea) to severe and life-threatening (such as seizures or coma). Symptom severity depends on the rapidity of development, duration, and severity of hyponatremia. Mild chronic hyponatremia is associated with cognitive impairment, gait disturbances, and increased rates of falls and fractures. In a prospective study, patients with hyponatremia more frequently reported a history of falling compared with people with normal serum sodium levels (23.8% vs 16.4%, respectively; P < .01) and had a higher rate of new fractures over a mean follow-up of 7.4 years (23.3% vs 17.3%; P < .004). Hyponatremia is a secondary cause of osteoporosis. When evaluating patients, clinicians should categorize them according to their fluid volume status (hypovolemic hyponatremia, euvolemic hyponatremia, or hypervolemic hyponatremia). For most patients, the approach to managing hyponatremia should consist of treating the underlying cause. Urea and vaptans can be effective treatments for the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure, but have adverse effects (eg, poor palatability and gastric intolerance with urea; and overly rapid correction of hyponatremia and increased thirst with vaptans). Severely symptomatic hyponatremia (with signs of somnolence, obtundation, coma, seizures, or cardiorespiratory distress) is a medical emergency. US and European guidelines recommend treating severely symptomatic hyponatremia with bolus hypertonic saline to reverse hyponatremic encephalopathy by increasing the serum sodium level by 4 mEq/L to 6 mEq/L within 1 to 2 hours but by no more than 10 mEq/L (correction limit) within the first 24 hours. This treatment approach exceeds the correction limit in about 4.5% to 28% of people. Overly rapid correction of chronic hyponatremia may cause osmotic demyelination, a rare but severe neurological condition, which can result in parkinsonism, quadriparesis, or even death.

CONCLUSIONS AND RELEVANCE

Hyponatremia affects approximately 5% of adults and 35% of patients who are hospitalized. Most patients should be managed by treating their underlying disease and according to whether they have hypovolemic, euvolemic, or hypervolemic hyponatremia. Urea and vaptans can be effective in managing the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure; hypertonic saline is reserved for patients with severely symptomatic hyponatremia.

Syndrome of inappropriate antidiuretic hormone secretion

Hyponatremia is the most frequent electrolytic disorder in hospitalized patients, and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), the most frequent cause of hiponatremia with clinically normal extracellular volume. It consists of a disorder of the regulation of body water that obeys to different causes, mainly cancer, pulmonary illnesses, disorders of the central nervous system and diverse drugs. As in any hiponatremia it a physiological knowledge of the regulation of body water and sodium is essential as well as the application of precise diagnostic criteria in order to manage the problem with an effective treatment. The available data until the moment show that the clinical diagnosis of SIADH made by professionals is mainly not supported on the established criteria drawn by experts and this lack of accuracy probably hits in the therapeutic result. The basis of the treatment of the SIADH is to correct its cause, water restriction, solutes (sodium chloride) and the use of vaptans in case of failure of the previous measures.

Tonicity Matters, Especially in Complex Hyponatremia Resulting from Pseudo-, Trans-locational, and True Hypotonic Hyponatremia: An Educational Case Report

Serum tonicity is defined by the serum concentrations of sodium (sNa) and glucose, which can promote free water movement across intra/extracellular compartments. Rapid changes in serum tonicity can cause brain damage. We herein report an educational case of a patient with hyponatremia (sNa: 112 mEq/L) concomitant with acute alcoholic pancreatitis. The cause of hyponatremia was considered complex. Pseudo- and trans-locational natremia was secondary to hyperglycemia (721 mg/dL) and hypertriglyceridemia (1,768 mg/dL), respectively, and true hypotonic hyponatremia. Regarding sNa correction, rapid correction was suspected. However, this was safely managed by monitoring tonicity (not sNa or osmolarity), thereby avoiding brain damage.

Hyponatremia and Liver Transplantation: A Narrative Review

Hyponatremia is a common electrolyte disorder in patients with end-stage liver disease (ESLD) and is associated with increased mortality on the liver transplantation (LT) waiting list. The impact of hyponatremia on outcomes after LT is unclear. Ninety-day and one-year mortality may be increased, but the data are conflicting. Hyponatremic patients have an increased rate of complications and longer hospital stays after transplant. Although rare, osmotic demyelination syndrome (ODS) is a feared complication after LT in the hyponatremic patient. The condition may occur when the serum sodium (sNa) concentration increases excessively during or after LT. This increase in sNa concentration correlates with the degree of preoperative hyponatremia, the amount of intraoperative blood loss, and the volume of intravenous fluid administration. The risk of developing ODS after LT can be mitigated by avoiding large perioperative increases in sNa concentration . This can be achieved through measures such as carefully increasing the sNa pretransplant, and by limiting the intravenous intra- and postoperative amounts of sodium infused. SNa concentrations should be monitored regularly throughout the entire perioperative period.

Challenging management dogma where evidence is non-existent, weak or outdated

Medical practice is dogged by dogma. A conclusive evidence base is lacking for many aspects of patient management. Clinicians, therefore, rely upon engrained treatment strategies as the dogma seems to work, or at least is assumed to do so. Evidence is often distorted, overlooked or misapplied in the re-telling. However, it is incorporated as fact in textbooks, policies, guidelines and protocols with resource and medicolegal implications. We provide here four examples of medical dogma that underline the above points: loop diuretic treatment for acute heart failure; the effectiveness of heparin thromboprophylaxis; the rate of sodium correction for hyponatraemia; and the mantra of "each hour counts" for treating meningitis. It is notable that the underpinning evidence is largely unsupportive of these doctrines. We do not necessarily advocate change, but rather encourage critical reflection on current practices and the need for prospective studies.

Hyponatraemic seizure secondary to primary polydipsia following urological surgery

An 82-year-old man presented to the emergency department with delirium, vomiting and an initial hyponatraemia of 112 mmol/L the day after successful transurethral vaporisation of the prostate. He had a tonic-clonic seizure in the acute surgical unit and was managed subsequently in the intensive care unit with a controlled rate of hypertonic saline. Initial work-up for the cause of hyponatraemia revealed a low urine osmolality, suggestive of relative excess water intake. Detailed examination of the operation notes revealed no discrepancy between intraoperative irrigating fluid input and output. Careful collateral history revealed that the patient had drunk 8 L of water in the 24 hours following the operation, after taking advice to 'drink plenty of water' literally. This case highlights the importance of conveying specific advice to patient, the lower incidence of transurethral resection syndrome in resections using saline as an irrigation fluid and outlines the pathway for investigation and management for hyponatraemia.

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 young man with secondary adrenal insufficiency due to empty sella syndrome

Background

Empty sella syndrome is characterized by a constellation of symptoms that encompass various systems, and includes endocrine, neurologic, ophthalmologic, and psychiatric presentations. We here report a case of a young man presenting with severe hyponatremia due to empty sella syndrome and focus on changes in electrolytes during corticosteroid supplementation.

Case report

A 36-year-old man presented with general weakness, poor appetite, and dizziness for 4 days. Physical assessment revealed lower limbs nonpitting oedema. Pertinent laboratory data showed severe hyponatremia (sodium 108 mmol/L). Endocrine work-up revealed low cortisol levels at 1.17 µg/dL (reference: 4.82–19.5 µg/dL) and inappropriately normal adrenocorticotropic hormone levels at 12.4 pg/mL (reference: 0.1–46.0 pg/mL), indicating secondary adrenal insufficiency. Brain magnetic resonance imaging confirmed the diagnosis of empty sella syndrome. He developed delirium and agitation one day after cortisol supplementation with a sodium correction rate of 10 mmol/L/day, while hypokalaemia (potassium 3.4 mmol/L) also developed. The symptoms improved after lowering the serum sodium level. This patient was eventually discharged after 12 days of hospitalization when the serum sodium and potassium levels were 139 mmol/L and 3.5 mmol/L, respectively.

Conclusion

Herein, we address the importance of timely diagnosis of empty sella syndrome in patients with hyponatremia and highlight the close monitoring of the changes in electrolytes during corticosteroid replacement.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02699-6.

A Standard Hemodialysis Prescription to Prevent Osmotic Demyelination in Hyponatremic Patients Requiring Dialysis

INTRODUCTION

We aimed to investigate the effect of a standard hemodialysis prescription in hyponatremic patients requiring hemodialysis on the development of osmotic demyelination syndrome.

METHODS

Ninety-nine patients who were treated with hemodialysis for the first time and had a pre-dialysis sodium value of ≤125 meq/L included in the study. Standard hemodialysis treatment was applied to all patients. Biochemical data before, immediately after and 24-hours after hemodialysis were recorded retrospectively. All patients followed up for two weeks and magnetic resonance imaging was performed in patients with neurological symptoms.

RESULTS

Eight patients had a sodium increase of more than 12 meq/L at 24-hours after hemodialysis. Although rapid correction of hyponatremia with hemodialysis, none of the 99 azotemic patients developed osmotic demyelination syndrome.

CONCLUSION

We did not observe osmotic demyelination syndrome in hyponatremic patients with azotemia treated with standard protocol hemodialysis. However, caution should still be exercised in high-risk patients for osmotic demyelination. This article is protected by copyright. All rights reserved.

Risk factors for overcorrection of severe hyponatremia: a post hoc analysis of the SALSA trial

Background

Hyponatremia overcorrection can result in irreversible neurologic impairment such as osmotic demyelination syndrome. Few prospective studies have identified patients undergoing hypertonic saline treatment with a high risk of hyponatremia overcorrection.

Methods

We conducted a post hoc analysis of a multicenter, prospective randomized controlled study, the SALSA trial, in 178 patients aged above 18 years with symptomatic hyponatremia (mean age, 73.1 years; mean serum sodium level, 118.2 mEq/L). Overcorrection was defined as an increase in serum sodium levels by >12 or 18 mEq/L within 24 or 48 hours, respectively.

Results

Among the 178 patients, 37 experienced hyponatremia overcorrection (20.8%), which was independently associated with initial serum sodium level (≤110, 110–115, 115–120, and 120–125 mEq/L with 7, 4, 2, and 0 points, respectively), chronic alcoholism (7 points), severe symptoms of hyponatremia (3 points), and initial potassium level (<3.0 mEq/L, 3 points). The NASK (hypoNatremia, Alcoholism, Severe symptoms, and hypoKalemia) score was derived from four risk factors for hyponatremia overcorrection and was significantly associated with overcorrection (odds ratio, 1.41; 95% confidence interval, 1.24–1.61; p < 0.01) with good discrimination (area under the receiver-operating characteristic [AUROC] curve, 0.76; 95% CI, 0.66–0.85; p < 0.01). The AUROC curve of the NASK score was statistically better compared with those of each risk factor.

Conclusion

In treating patients with symptomatic hyponatremia, individuals with high hyponatremia overcorrection risks were predictable using a novel risk score summarizing baseline information.

Prevalence and clinical significance of serum sodium variability in patients with acute-on-chronic liver diseases: a prospective multicenter study in China

Background

No reports exist regarding the prevalence of different Na levels and their relationship with 90-day prognosis in hospitalized patients with acute-on-chronic liver disease (AoCLD) in China. Therefore, the benefit of hyponatremia correction in AoCLD patients remains unclear.

Methods

We prospectively collected the data of 3970 patients with AoCLD from the CATCH-LIFE cohort in China. The prevalence of different Na levels (≤ 120; 120–135; 135–145; > 145) and their relationship with 90-day prognosis were analyzed. For hyponatremic patients, we measured Na levels on days 4 and 7 and compared their characteristics, based on whether hyponatremia was corrected.

Results

A total of 3880 patients were involved; 712 of those developed adverse outcomes within 90 days. There were 80 (2.06%) hypernatremic, 28 (0.72%) severe hyponatremic, and 813 (20.95%) mild hyponatremic patients at admission. After adjusting for all confounding factors, the risk of 90-day adverse outcomes decreased by 5% (odds ratio [OR] 0.95; 95% confidence interval [CI] 0.93–0.97; p < 0.001), 24% (OR 0.76; 95% CI 0.70–0.84; p < 0.001), and 42% (OR 0.58; 95% CI 0.49–0.70; p < 0.001) as Na level increased by 1, 5, and 10 mmol/L, respectively. Noncorrection of hyponatremia on days 4 and 7 was associated with 2.05-fold (hazard ratio [HR], 2.05; 95% CI, 1.50–2.79; p < 0.001) and 1.46-fold (HR 1.46; 95% CI 1.05–2.02; p = 0.028) higher risk of adverse outcomes.

Conclusions

Hyponatremia was an independent risk factor for a poor 90-day prognosis in patients with AoCLD. Failure to correct hyponatremia in a week after admission was often associated with increased mortality. (ClinicalTrials.gov number: NCT02457637, NCT03641872).

Clinical Trial Numbers

This study is registered at Shanghai www.clinicaltrials.org (NCT02457637 and NCT03641872).

Supplementary Information

The online version contains supplementary material available at 10.1007/s12072-021-10282-8.

Clinical characteristics and outcomes of hyponatraemia associated with oral water intake in adults: a systematic review

INTRODUCTION

Excessive water intake is rarely associated with life-threatening hyponatraemia. The aim of this study was to determine the clinical characteristics and outcomes of hyponatraemia associated with excess water intake.

METHODS

This review was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All studies (case reports, observational or interventional studies) reporting excess water intake and hyponatraemia in adults (1946-2019) were included.

RESULTS

A total of 2970 articles were identified and 177 were included (88.7% case reports), consisting of 590 patients. The mean age was 46±16 years (95% CI 44 to 48 years), 47% female, 52% had a chronic psychiatric disorder and 31% had no underlying condition. The median volume of water consumed and serum sodium at presentation was 8 L/day (95% CI 8.9 to 12.2 L/day) and 118 mmol/L (95% CI 116 to 118 mmol/L), respectively. The motivator for increased water consumption was psychogenic polydipsia (55%); iatrogenic (13%); exercise (12%); habitual/dipsogenic polydipsia (7%) and other reasons (13%). The clinical features on presentation were severe in 53% (seizures, coma); moderate in 35% (confusion, vomiting, agitation) and mild in 5% (dizziness, lethargy, cognitive deficit) and not reported in 5% of studies. Treatment was supportive in 41% of studies (fluid restriction, treatment of the underlying cause, emergency care), and isotonic and hypertonic saline was used in 18% and 28% of cases, respectively. Treatment-related complications included osmotic demyelination (3%) and rhabdomyolysis (7%), and death occurred in 13% of cases.

CONCLUSION

Water intoxication is associated with significant morbidity and mortality and requires daily intake to substantially exceed population-based recommendations. The limitations of this analysis are the low quality and high risk of bias of the included studies.

PROSPERO REGISTRATION NUMBER

A pre-existing protocol in the international prospective register of systematic reviews was updated to incorporate any new amendments and reregistered at http://www.crd.york.ac.uk/PROSPERO (registration no. CRD42019129809).

Clinical Experience of the Efficacy and Safety of Low-dose Tolvaptan Therapy in a UK Tertiary Oncology Setting

CONTEXT

In patients with cancer, hyponatremia is associated with increased morbidity and mortality and can delay systemic therapy.

OBJECTIVE

To assess the safety and efficacy of low-dose tolvaptan (7.5 mg) for hospitalized, adult patients with hyponatremia due to syndrome of inappropriate antidiuresis (SIAD), and coexisting malignancy.

METHODS

Retrospective evaluation in a tertiary cancer center.

RESULTS

Fifty-five patients with mean baseline serum sodium (sNa) 117.9 ± 4.6 mmol/L were included. In total, 90.9% had severe hyponatremia (sNa < 125 mmol/L). Mean age was 65.1 ± 9.3 years. Following an initial dose of tolvaptan 7.5 mg, median (range) increase in sNa observed at 24 hours was 9 (1-19) mmol/L. Within 1 week, 39 patients (70.9%) reached sNa ≥ 130 mmol/L and 48 (87.3%) had sNa rise of ≥5 mmol/L within 48 hours. No severe adverse events were reported. Thirty-three (60%) and 17 (30.9%) patients experienced sNa rise of ≥8 and ≥12 mmol/L/24 hours, respectively. The rate of sNa correction in the first 24 hours was significantly higher among participants that continued fluid restriction after tolvaptan administration (median [quantiles]: 14 [9-16] versus 8 [5-11] mmol/L, P = .036). Moreover, in the over-rapid correction cohort (≥12 mmol/L/24 hours) demeclocycline was appropriately discontinued only in 60% compared with 91.7% of the remaining participants (P = .047). Lower creatinine was predictive of higher sNa correction rate within 24 hours (P = .01).

CONCLUSION

In the largest series to date, although low-dose tolvaptan was demonstrated to be effective in correcting hyponatremia due to SIAD in cancer patients, a significant proportion experienced over-rapid correction. Concurrent administration of demeclocycline and/or fluid restriction must be avoided due to the increased risk of over-rapid correction.

Hemodynamic Instability During Liver Transplantation in Patients With End-stage Liver Disease: A Consensus Document from ILTS, LICAGE, and SATA

Hemodynamic instability (HDI) during liver transplantation (LT) can be difficult to manage and increases postoperative morbidity and mortality. In addition to surgical causes of HDI, patient- and graft-related factors are also important. Nitric oxide-mediated vasodilatation is a common denominator associated with end-stage liver disease related to HDI. Despite intense investigation, optimal management strategies remain elusive. In this consensus article, experts from the International Liver Transplantation Society, the Liver Intensive Care Group of Europe, and the Society for the Advancement of Transplant Anesthesia performed a rigorous review of the most current literature regarding the epidemiology, causes, and management of HDI during LT. Special attention has been paid to unique LT-associated conditions including the causes and management of vasoplegic syndrome, cardiomyopathies, LT-related arrhythmias, right and left ventricular dysfunction, and the specifics of medical and fluid management in end-stage liver disease as well as problems specifically related to portal circulation. When possible, management recommendations are made.

Hyponatremia Intervention Trial (HIT): Study Protocol of a Randomized, Controlled, Parallel-Group Trial With Blinded Outcome Assessment

Background: Hyponatremia is the most common electrolyte disorder with a prevalence of up to 30% in hospitalized patients. In contrast to acute hyponatremia where the need for immediate treatment is well-recognized, chronic hyponatremia is often considered not clinically relevant. This is illustrated by reports showing that appropriate laboratory tests are ordered in <50% of patients and that up to 75% are still hyponatremic at discharge. At the same time, emerging evidence suggests an association between hyponatremia and adverse events including increased risk of mortality and rehospitalization. Methods: This is a randomized (1:1 ratio) controlled, superiority, parallel-group international multi-center trial with blinded outcome assessment. In total 2,278 participants will be enrolled. Participants will be randomly assigned to undergo either targeted correction of plasma sodium levels or standard of care during hospitalization. The primary outcome is the combined risk of death or re-hospitalization within 30 days. Discussion: All data on hyponatremia and mortality are derived from observational studies and often lack methodologic robustness. Consequently, the direct impact of hyponatremia on mortality and rehospitalization risk is still debated, resulting in a clinical equipoise whether in-hospital chronic hyponatremia should be treated or not. Therefore, a randomized controlled trial is required to study whether targeted plasma sodium correction reduces the risk of mortality and rehospitalization associated with hyponatremia. Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT03557957.

An Unusual Cause of Bulbar Palsy in the Emergency Department

BACKGROUND

Osmotic demyelination syndrome commonly occurs after rapid correction of hyponatremia. But it has also been reported after graded correction of hyponatremia in the presence of other risk factors like chronic alcoholism, malnutrition, liver disease, and hypokalemia.

CASE REPORT

We report a case of a 67-year-old man who presented with dysphagia and nasal regurgitation and had features suggestive of bulbar palsy on neurological examination. He had spontaneous rapid correction of hyponatremia from a serum sodium level of 122 mEq/L to 132 mEq/L after discharge from our hospital. Neuroimaging was suggestive of extrapontine myelinolysis involving the basal ganglia. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: An emergency physician should be aware of this because osmotic demyelination syndrome should also be considered in the differential diagnosis of patients presenting with bulbar palsy to the emergency department.

Acute and Chronic Hyponatremia

Hyponatremia is the most common electrolyte disorder in clinical practice. Catastrophic complications can occur from severe acute hyponatremia and from inappropriate management of acute and chronic hyponatremia. It is essential to define the hypotonic state associated with hyponatremia in order to plan therapy. Understanding cerebral defense mechanisms to hyponatremia are key factors to its manifestations and classification and subsequently to its management. Hypotonic hyponatremia is differentiated on the basis of urine osmolality, urine electrolytes and volume status and its treatment is decided based on chronicity and the presence or absence of central nervous (CNS) symptoms. Proper knowledge of sodium and water homeostasis is essential in individualizing therapeutic plans and avoid iatrogenic complications while managing this disorder.

Central pontine myelinolysis and the osmotic demyelination syndromes: an open and shut case?

Central pontine myelinolysis and extrapontine myelinolysis are collectively called the osmotic demyelination syndromes. Despite being described in 1959, there are several aspects of the disorder that remain an enigma. Animal models and neuroimaging techniques have allowed us to understand the condition better. From being a universally fatal disorder that was diagnosed post mortem, increased awareness, neuroimaging techniques and supportive care have enabled us to make the diagnosis ante-mortem. This has also led to a significant drop in associated mortality. The aim of this review is to highlight the clinical spectrum, neuroimaging findings, and recent developments.