Hyponatraemia: an overview of frequency, clinical presentation and complications

Approach to the Patient: Hyponatremia and the Syndrome of Inappropriate Antidiuresis (SIAD)

Hyponatremia is the most common electrolyte disturbance seen in clinical practice, affecting up to 30% of acute hospital admissions, and is associated with significant adverse clinical outcomes. Acute or severe symptomatic hyponatremia carries a high risk of neurological morbidity and mortality. In contrast, chronic hyponatremia is associated with significant morbidity including increased risk of falls, osteoporosis, fractures, gait instability, and cognitive decline; prolonged hospital admissions; and etiology-specific increase in mortality. In this Approach to the Patient, we review and compare the current recommendations, guidelines, and literature for diagnosis and treatment options for both acute and chronic hyponatremia, illustrated by 2 case studies. Particular focus is concentrated on the diagnosis and management of the syndrome of inappropriate antidiuresis. An understanding of the pathophysiology of hyponatremia, along with a synthesis of the duration of hyponatremia, biochemical severity, symptomatology, and blood volume status, forms the structure to guide the appropriate and timely management of hyponatremia. We present 2 illustrative cases that represent common presentations with hyponatremia and discuss the approach to management of these and other causes of hyponatremia.

Preoperative Hyponatremia Indicates Complicated Acute Appendicitis

INTRODUCTION

Acute appendicitis is the most common surgical emergency. Early detection of patients with complicated appendicitis leads to prompt surgical management and better outcome. This study investigated the relationship between the severity of acute appendicitis and the presence of preoperative hyponatremia.

MATERIALS AND METHODS

We retrospectively reviewed the medical files of adult patients operated on for acute appendicitis over a 6-year period. Hyponatremia was defined as serum sodium level of ≤135 mEq/L. Patients were classified into complicated appendicitis and noncomplicated appendicitis according to operative findings and/or histopathology reports.

RESULTS

A total of 129 patients were identified and included in this study. Complicated appendicitis was found more frequently in female patients and older patients. Hyponatremia was found significantly more frequently in patients with complicated appendicitis (p < 0.001) and also in patients with perforation than without perforation (p=0.047).

CONCLUSIONS

The present study demonstrated that preoperative hyponatremia is associated with complicated appendicitis. Serum sodium levels, a routine, low-cost laboratory test, could act as an accessory marker aiding surgeons in earlier identification of gangrenous or perforated acute appendicitis.

The vasopressin-aquaporin-2 pathway syndromes

Vasopressin is the key hormone involved in water conservation and regulation of water balance, essential for life. In the renal collecting duct, vasopressin binds to the V2 receptor, increasing water permeability through activation of aquaporin-2 redistribution to the luminal membrane. This mechanism promotes rapid water reabsorption, important for immediate survival; however, only recently it has become clear that long-term adverse effects are associated with alterations of the vasopressin-aquaporin-2 pathway, leading to several syndromes associated with water balance disorders. The kidney resistance to the vasopressin action may cause severe dehydration for patients and, conversely, nonosmotic release of vasopressin is associated with water retention and increasing the circulatory blood volume. This chapter discusses the relevance of the altered vasopressin-aquaporin-2 pathway in some diseases associated with water balance disorders, including congenital nephrogenic diabetes insipidus, syndrome of inappropriate secretion of antidiuretic hormone, nephrogenic syndrome of inappropriate antidiuresis, and autosomal dominant polycystic kidney disease. The emerging picture suggests that targeting the vasopressin-AQP2 axis can provide therapeutic benefits in those patients.

Levels of C-Reactive Protein and Sodium May Differentiate a Perforated Appendix from a Nonperforated Appendix in Children

Background

Acute appendicitis (AA) might be amenable to conservative antibiotic treatment, whereas a perforated appendix (PA) necessitates surgery. We investigated the value of clinical–laboratory markers in distinguishing AA from a PA.

Methods

Retrospectively obtained preoperative parameters for 306 consecutive patients (<18 years) with histologically confirmed appendicitis (AA (n = 237) vs. PA (n = 69)), treated at our institution between January 2014 and December 2017.

Results

A PA was associated with male preponderance, younger age, decreased sodium level and increased white blood cell count, Tzanakis score, C-reactive protein (CRP) level, and CRP-to-lymphocyte ratio (CLR). Upon discrimination analysis, CLR and CRP displayed the highest accuracy in differentiating a PA from AA. Regression analysis identified levels of CRP, sodium, and the Tzanakis score as independent predictors for a PA.

Conclusion

Levels of CLR, CRP, sodium, and Tzanakis score might support decision-making regarding treatment options for pediatric appendicitis.

Redefined hyponatremia as a marker to exclude the diagnosis of anastomotic leakage after colorectal cancer surgery

Objective

Our objective was to investigate the association between anastomotic leakage (AL) and hyponatremia after colorectal cancer surgery.

Methods

All anastomoses in colorectal cancer surgery performed in our hospital between January 2015 and December 2017 were retrospectively identified. According to the diagnostic criteria of AL, the patients were divided into an AL group and a no anastomotic leakage (NAL) group.

Results

We reviewed records of 498 consecutive colorectal cancer patients. The total incidence of AL was 5.4%. Postoperative serum sodium levels differed significantly: 137.63 ± 4.29 and 139.81 ± 3.41 mmol/L in the AL and NAL groups, respectively. By using area under the receiver-operating characteristic (auROC) curves, we determined the optimum postoperative serum sodium cut-off to be 139.5 mmol/L and redefined hyponatremia as postoperative serum sodium <139.5 mmol/L. Redefined hyponatremia had an auROC of 0.65, corresponding to a 97.2% negative predictive value. The negative predictive value reached 99.1% when serum sodium level was combined with leukocytosis. Multivariable analysis found that redefined hyponatremia (odds ratio, 1.176) was an independent predictive factor for AL.

Conclusions

Redefined hyponatremia has good negative predictive value for AL diagnosis after colorectal cancer surgery and could be used as a marker to exclude the diagnosis.

Efficacy of a Newly Modified Short Hydration Method for Gemcitabine and Cisplatin Combination Chemotherapy in Patients with Urothelial Carcinoma

INTRODUCTION

Conventional first-line chemotherapy for patients with metastatic urothelial carcinoma (UC) is gemcitabine and cisplatin (GC). However, cisplatin can cause renal failure, necessitating abundant fluid replacement and hospitalization during treatment. Recent evidence exists for short hydration methods in cisplatin-based chemotherapy.

OBJECTIVE

This study aims to analyze the efficacy of newly established modified short hydration GC (m-shGC) therapy in patients with UC.

METHODS

From May 2017 to March 2019, 48 patients with UC who received m-shGC therapy were treated with 1,000 mg/m2 gemcitabine on days 1, 8, and 15, and 70 mg/m2 cisplatin and 2,000 mL fluid replacement on day 1, in each 28-day cycle. We retrospectively evaluated renal function, serum electrolyte abnormalities, and adverse events (AEs) following treatment, and retrospectively compared patients under m-shGC therapy with those under conventional GC (c-GC) therapy from 2015 to 2017. In addition, from April 2019 to August 2019 in a prospective analysis, 15 patients were newly enrolled, and AE profiles and physical activity during m-shGC therapy were quantified using a wearable tracker.

RESULTS

In a retrospective analysis of 101 patients (53 c-GC and 48 m-shGC), patient characteristics were not statistically significant between the two groups. Myelosuppression, including predominant neutropenia and decreased platelets, fatigue, nausea, and constipation were the main common AEs. However, renal function and serum sodium levels in the m-shGC group remained unchanged. Grade 3-4 AEs were not more severe in the m-shGC compared with the c-GC group. Furthermore, in a prospective analysis using a wearable tracker, the amount of walking by patients on day 1 significantly declined. However, immediate recovery occurred reflecting the short hydration.

CONCLUSION

Our m-shGC therapy has an acceptable AE profile compared with conventional therapy, with UC patients showing good physical activity.

Prognostic significance of hyponatremia induced by systemic chemotherapy in a hospital-based propensity score-matched analysis

BACKGROUND

During chemotherapy, hyponatremia is one of the most frequently encountered adverse effects. This study aimed to investigate the prognostic impact of hyponatremia induced by systemic chemotherapy (HIC) using a propensity matching method in cumulative pooled data.

METHODS

Between January 2011 and July 2017, 2129 patients were administered systemic chemotherapy for malignancy in various organs at Nagoya City University Hospital. Patients were divided into two groups: a grade 0-1 group (control group) and a grade 3-4 group (severe group) according to the severity of HIC appearing within 30 days after starting treatment. Kaplan-Meier curves were used for survival and recurrence analyses using a propensity case-matched analysis.

RESULT

The number of severe HIC patients was 93 (4.4%). In platinum-containing regimens, HIC appeared at higher frequencies. In the 21.2 months median follow-up period, the median OS (mOS) in the severe group was 49.1 months, which was significantly worse than the mOS in the control group; the OS in the control group did not reach the median. Univariate and multivariate analyses of associated factors in patients with grade 3-4 HIC revealed that renal dysfunction, cisplatin-containing regimen, and infusion of more than 5000 mL fluid was associated with HIC.

CONCLUSION

This study suggests that severe HIC in the first treatment cycle affects survival time. Chemotherapy patients receiving extensive hydration should be required to undergo frequent monitoring of serum sodium levels, especially patients receiving platinum-containing regimens.

A new experimental mouse model of water intoxication with sustained increased intracranial pressure and mild hyponatremia without side effects of antidiuretics

The most used experimental mouse model of hyponatremia and elevated intracranial pressure (ICP) is intraperitoneal injection of water in combination with antidiuretics. This model of water intoxication (WI) results in extreme pathological changes and death within 1 h. To improve preclinical studies of the pathophysiology of elevated ICP, we characterized diuresis, cardiovascular parameters, blood ionogram and effects of antidiuretics in this model. We subsequently developed a new mouse model with mild hyponatremia and sustained increased ICP. To investigate the classical protocol (severe WI), C57BL/6mice were anesthetized and received an intraperitoneal injection of 20% body weight of MilliQ water with or without 0.4 µg·kg^-1 desmopressin acetate (dDAVP). Corresponding Sham groups were also studied. In the new WI protocol (mild WI), 10% body weight of a solution containing 6.5 mM NaHCO₃, 1.125 mM KCl and 29.75 mM NaCl was intraperitoneally injected. By severe WI, ICP and mean arterial pressure increased until brain stem herniation occurred (23 ± 3 min after injection). The cardiovascular effects were accelerated by dDAVP. Severe WI induced a halt to urine production irrespective of the use of dDAVP. Following the new mild WI protocol, ICP also increased but was sustained at a pathologically high level without inducing herniation. Mean arterial pressure and urine production were not affected during mild WI. In conclusion, the new mild WI protocol is a superior experimental model to study the pathophysiological effects of elevated ICP induced by water intoxication.

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.

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

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

Recurrent Hyponatremia as Presenting Manifestation of Pituitary Macroadenoma

Hyponatremia is commonly seen electrolyte disturbance clinically. It is potentially life-threatening and requires prompt diagnosis and treatment. Non-functioning pituitary macroadenoma generally presents with a headache, visual disturbances, and the diagnosis is often delayed because of nonspecific nature of symptoms. Hyponatremia being initial manifestation before other common symptoms of pituitary macroadenoma is rare. We present a case of 55-year-old male with recurrent episodes of hyponatremia who was found to non-functioning pituitary macroadenoma along with panhypopituitarism. He was managed with hormone replacements. Our case highlights the importance of correct diagnosis of hyponatremia, measurement of the thyroid, adrenal and pituitary function in cases of hyponatremia.

Neuronal distress induced by low extracellular sodium in vitro is partially reverted by the return to normal sodium

BACKGROUND

Hyponatremia is associated with negative clinical outcomes even when chronic and mild. It is also known that hyponatremia treatment should be appropriately performed, to avoid dramatic consequences possibly leading to death. We have previously demonstrated that chronically low extracellular [Na(+)], independently of reduced osmolality, is associated with signs of neuronal cell distress, possibly involving oxidative stress.

AIM

The aim of the present study was to assess whether the return to normal extracellular [Na(+)] is able to revert neuronal cell damage.

METHODS

After exposing SH-SY5Y and SK-N-AS cells to low [Na(+)] and returning to normal [Na(+)], we analyzed cell viability by MTS assay, ROS accumulation by FASCan and expression of anti-apoptotic genes.

RESULTS

We found that the viability of cells was restored upon return to normal [Na(+)]. However, when more subtle signs of cell distress were assessed, such as the expression level of the anti-apoptotic genes Bcl-2 and DHCR24 or of the heme oxygenase 1 gene, a complete return to basal values was not observed, in particular in SK-N-AS, even when [Na(+)] was gradually increased. We also demonstrated that the amount of ROS significantly increased in low [Na(+)], thus confirming that oxidative stress appears to contribute to the effects of low [Na(+)] on cell homeostasis.

CONCLUSIONS

Overall, this study provided the first demonstration that the correction of chronically low extracellular [Na(+)] may not be able to revert all the cell alterations associated with reduced [Na(+)]. These results suggest that prompt hyponatremia treatment might prevent possible residual abnormalities.

Hyponatremia and hypernatremia are associated with increased 30-day mortality in hip fracture patients

Using data from the Danish national registries on 7317 patients, this study shows that abnormal plasma sodium levels, in the form of hyponatremia and hypernatremia, are prevalent and associated with increased 30-day mortality in hip fracture patients.

INTRODUCTION

The aim of this study was to examine the prevalence of hyponatremia and hypernatremia in patients admitted with a fractured hip as well as the association with 30-day in mortality in these patients.

METHODS

A total of 7317 hip fracture patients (aged 60 years or above) with admission plasma sodium measurements were included. Data on comorbidity, medication, and death was retrieved from Danish national registries. The association between plasma sodium and mortality was examined using Cox proportional hazard models.

RESULTS

The prevalence of hyponatremia and hypernatremia on admission was 19.0 and 1.7 %, respectively. Thirty-day mortality was increased for patients with hyponatremia (12.2 %, p = 0.005) and hypernatremia (15.5 %, p = 0.03) compared to normonatremic patients (9.6 %). After adjustment for possible confounding factors, hyponatremia (1.38 [1.16-1.64], p = 0.0003) and hypernatremia (1.71 [1.08-2.70], p = 0.02) were still associated with increased risk of death by 30 days. Looking at the association between changes in plasma sodium during admission and mortality, there was no difference between patients with normalized and persistent hyponatremia (10.4 vs 11.3 %, p = 0.6) while a lower mortality was found for normalized hypernatremia compared to persistent hypernatremia (12.4 vs 33.3 %, p = 0.03).

CONCLUSIONS

This study shows that abnormal plasma sodium levels are prevalent in patients admitted with a fractured hip and that both hyponatremia and hypernatremia are associated with increased risk of death within 30 days of admission.

Hyponatraemic encephalopathy: an unusual stroke mimic

We present a case of a 74-year-old man who was admitted to our stroke unit with symptoms and signs suggestive of a left total anterior circulation stroke. Subsequent MRI failed to support this diagnosis and, furthermore, correction of an incidental finding of hyponatraemia due to syndrome of inappropriate antidiuretic hormone secretion led to a complete recovery of symptoms. Investigation and subsequent exclusion of other potential differential diagnoses confirmed the diagnosis of hyponatraemia mimicking acute stroke.

A prospective study to compare the clinical efficacy of Tolvaptan with 3% hypertonic saline solution in hospitalized patients having hyponatremia

Objective:

Hyponatremia is one of the most common electrolyte abnormalities in hospitalized patients. The treatment of hyponatremia is controversial as rapid correction of serum sodium can give rise to neurologic disorder and at the same time if not corrected timely, it can lead to brain damage. The aim of this study was to compare the efficacy of Tolvaptan with 3% hypertonic saline solution for the management of hyponatremia in hospitalized patients.

Methods:

In this prospective observational study, data of 60 hospitalized patients having hyponatremia from February 2013 to July 2013 were collected and analyzed. Patients either received oral Tolvaptan or intravenous infusion of 3% hypertonic saline solution. The serum sodium concentration before administration of treatment and 24 h and 48 h after the administration of the drugs were recorded and analyzed. Data were analyzed using GraphPad Software, by Student's paired t-test and one-way analysis of Variance (ANOVA).

Findings:

Tolvaptan and 3% hypertonic saline solution had significant effects in raising serum sodium level in hyponatremic patients at both 24 h and 48 h (P < 0.0001). This increase was about 8.030 ± 0.6507 mEq/L and 12.33 ± 0.6489 mEq/L for 3% hypertonic saline and about 5.111 ± 0.6616 mEq/L and 10.11 ± 0.6230 mEq/L for Tolvaptan, after 24 h and 48 h, respectively.

Conclusion:

Both drugs had significant effects in raising serum sodium level in hyponatremic patients; however administration of 3% hypertonic saline solution had a slightly superior efficacy in raising the serum sodium concentration at both 24 h and 48 h periods in Hyponatremic patients compared with oral Tolvaptan.

Managing hyponatremia in adults

Hyponatremia can be challenging to manage, especially in older adults. Acute severe hyponatremia can cause significant morbidity and mortality, but too-rapid reversal of chronic hyponatremia can cause serious neurologic issues or death. This article reviews the causes, presentations, and management of hyponatremia in adults.

Apelin beyond kidney failure and hyponatremia: a useful biomarker for cancer disease progression evaluation

Apelin regulates angiogenesis, stimulating endothelial cell proliferation and migration. It is upregulated during tumor angiogenesis, and its overexpression was reported to increase tumor growth. Furthermore, apelin controls vasopressin release and body fluid homeostasis. The aim of this study was to examine the correlations between apelin expression and clinical outcomes in oncologic patients, such as cancer disease progression and patient's survival. Apelin levels were evaluated in a cohort of 95 patients affected by different varieties of cancer. Partial remission and stable disease were assigned to the 'no progression' group, comparing it with the progressor group. Patients were followed up for 2 years. Receiver operating characteristics analysis was employed for identifying the progression of the oncologic disease and Kaplan-Meier curves assessed the survival. Adjusted risk estimates for progression endpoint were calculated using Cox proportional hazard regression analysis. Oncologic patients had higher apelin levels compared with healthy subjects, and apelin was closely related to the stages of the disease. In the hyponatremia group, apelin values were significantly higher than patients with eunatremia. After the follow-up of 24 months, 41 patients (43%) reached the endpoint. Progressor subjects presented significantly increased apelin values at baseline compared with non-progressor. Univariate followed by multivariate Cox proportional hazard regression analysis showed that apelin predicted cancer progression independently of other potential confounders. In patients with cancer, apelin closely reflects the stage of the disease and represents a strong and independent risk marker for cancer progression.

Hyponatremia is a specific marker of perforation in sigmoid diverticulitis or appendicitis in patients older than 50 years

Introduction. This study aimed to evaluate symptoms and signs, inflammation markers, electrolytes, and ECG signs of increased vagal tone as markers of colon perforation in sigmoid diverticulitis or appendicitis. Methods. The records of all patients older than fifty years (only these had routine ECG done) admitted to our emergency station between January 2008 and December 2010 with sigmoid diverticulitis (n = 198, diagnosed by computer tomography) or appendicitis (n = 84, diagnosed intraoperatively) were retrospectively evaluated. Pain score, heart rate, blood pressure, and body temperature were assessed at presentation. Before starting infusion therapy, blood was taken to do a blood count and to analyze CRP, the electrolytes, and creatinine levels. Then an ECG was done. Results. The perforation rate was 37% (n = 103). Body temperature, heart rate, sodium, CRP, and leukocytes correlated significantly with infectious colon perforation. However, only body temperature, CRP, and sodium correlated significantly with infectious colon perforation if compared by logistic regression analysis. The prevalence of hyponatremia (sodium level <136 mmol/L) was 29% in the group with infectious colon perforation and 16% in the group without (P = 0.013). Conclusion. Hyponatremia is a specific marker of infectious colon perforation in patients older than fifty years.

Child-Na score: a predictive model for survival in cirrhotic patients with symptomatic portal hypertension treated with TIPS

BACKGROUND AND AIM

Several models have been developed to predict survival in patients with cirrhosis undergoing TIPS; however, few of these models have gained widespread acceptance, especially in the era of covered stents. The aim of this study was to establish an evidence-based model for predicting survival after TIPS procedures.

METHODS

A total of 210 patients with cirrhosis treated with TIPS were considered in the study. We comprehensively investigated factors associated with one-year survival and developed a new predictive model using the Cox regression model.

RESULTS

In the multivariate analysis, the Child-Pugh score and serum sodium levels were independent predictors of one-year survival. A new score incorporating serum sodium into the Child-Pugh score was developed: Child-Na score. We compared the predictive accuracy of Child-Na score with that of other scores; only the Child-Na and MELD-Na scores had adequate predictive ability in patients with serum Na levels <138 mmol/L. The best Child-Na cut-off score (15.5) differentiated two groups of patients with distinct prognoses (one-year cumulative survival rates of 80.6% and 45.5%); this finding was confirmed in a validation cohort (n = 86). In a subgroup analysis stratifying patients by indication for TIPS, the Child-Na score distinguished patients with different prognoses.

CONCLUSIONS

Patients with variceal bleeding and a Child-Na score ≤15 had a better prognosis than patients with a score ≥16. Patients with refractory ascites and a Child-Na score ≥16 had a high risk of death after the TIPS procedures; caution should be used when treating these patients with TIPS.