Hyponatraemia at hospital admission is a predictor of overall mortality

Hyponatremia as a predictor of cognitive deterioration in hospitalized post-stroke patients

PURPOSE

Evidence is scarce regarding the association between hyponatremia and alterations in cognitive function among hospitalized older patients. We aimed to investigate the associations between hyponatremia and the baseline cognitive status, as well as the improvement in cognitive function, in hospitalized post-stroke patients.

METHODS

This retrospective cohort study included consecutive hospitalized post-stroke patients. Serum sodium concentrations were extracted from medical records based on blood tests performed within 24 h of admission, with hyponatremia defined as a serum sodium concentration < 135 mEq/L. The main outcomes included admission and discharge scores for cognitive levels, assessed through the cognitive domain of the Functional Independence Measure (FIM-cognition), as well as the score changes observed during the hospitalization period. Multivariate linear regression analyses were used to determine the association between hyponatremia and outcomes of interest, adjusted for potential confounders.

RESULTS

Data from 955 patients (mean age 73.2 years; 53.6 % men) were included in the analysis. The median baseline blood sodium level was 139 [137, 141], and 84 patients (8.8 %) exhibited hyponatremia. After full adjustment for confounders, the baseline hyponatremia was significantly and negatively associated with FIM-cognition values at admission (β = -0.009, p = 0.016), discharge (β = -0.038, p = 0.043), and the gain during hospital stay (β = -0.040, p = 0.011).

CONCLUSION

Baseline hyponatremia has demonstrated a correlation with decline in cognitive level over the course of rehabilitation in individuals after stroke. Assessing hyponatremia at the outset proves to be a pivotal prognostic indicator.

Associations between Baseline Hyponatremia and Activities of Daily Living and Muscle Health in Convalescent Stroke Patients

Objectives

Evidence is scarce regarding the association between hyponatremia and functional outcomes among older hospitalized patients. We aimed to evaluate the associations between baseline hyponatremia and improvement in activities of daily living (ADL) and muscle health in hospitalized post-stroke patients.

Methods

This retrospective cohort study included hospitalized post-stroke patients. Serum sodium concentrations were extracted from medical records based on blood tests performed within 24 h of admission, with hyponatremia defined as a serum sodium concentration below135 mEq/L. Primary outcome was the discharge ADL as assessed by the motor domain of the Functional Independence Measure (FIM-motor) and its corresponding gain during hospitalization. Other outcomes encompassed the discharge scores for skeletal muscle mass (SMI) and handgrip strength (HGS). Multivariate linear regression analyses were used to determine the association between hyponatremia and outcomes of interest, adjusted for potential confounders.

Results

Data from 955 patients (mean age 73.2 years; 53.6% men) were analyzed. The median baseline blood sodium level was 139 [interquartile range: 137, 141] mEq/L, and 84 patients (8.8%) exhibited hyponatremia. After full adjustment for confounders, baseline hyponatremia was significantly and negatively associated with FIM-motor at discharge (β=-0.036, P=0.033) and its gain during hospital stay (β=-0.051, P=0.033). Baseline hyponatremia exhibited an independent and negative association with discharge HGS (β=-0.031, P=0.027), whereas no significant association was found between baseline hyponatremia and discharge SMI (β=-0.015, P=0.244).

Conclusions

Baseline hyponatremia demonstrated a correlation with compromised ADL and muscle health in individuals undergoing rehabilitation after stroke.

The management of acute and chronic hyponatraemia

Hyponatraemia is the most common electrolyte abnormality encountered in clinical practice; despite this, the work-up and management of hyponatraemia remain suboptimal and varies among different specialist groups. The majority of data comparing hyponatraemia treatments have been observational, up until recently. The past two years have seen the publication of several randomised control trials investigating hyponatraemia treatments, both for chronic and acute hyponatraemia. In this article, we aim to provide a background to the physiology, cause and impact of hyponatraemia and summarise the most recent data on treatments for acute and chronic hyponatraemia, highlighting their efficacy, tolerability and adverse effects.

Hyponatraemia compounding pre-eclamptic toxaemia in a patient with type 1 diabetes

We report a case of profound, symptomatic hyponatraemia in association with pre-eclamptic toxaemia (PET) in a 38-year-old nulliparous woman with type 1 diabetes mellitus. This patient developed hypertension and proteinuria at 31+6 weeks' gestation and was admitted for management of pre-eclampsia. Severe headache, visual disturbance and nausea were associated with a hyponatraemia of 115 mmol/L followed by ketoacidosis. This was reversed through fluid restriction, supplementation with 1.8%-3.0% hypertonic saline and a volume-reduced variable-rate insulin infusion. Clinical stability was achieved and she was subsequently worked up for an induction of labour for worsening pre-eclampsia. Hyponatraemia in the context of PET has been previously reported as rare. However, it has complications that may significantly compound the sequelae of severe PET. We propose that specific and focused monitoring of serum sodium levels should become common practice in the management of women with this condition to allow for timely, measured correction of abnormalities.

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.

Low serum sodium levels at hospital admission: Outcomes among 2.3 million hospitalized patients

Background

Hyponatremia is the most common electrolyte disorder among hospitalized patients. Controversies still exist over the relationship between hyponatremia and outcomes of hospitalized patients.

Methods

To analyze the association of low serum sodium levels at hospital admission with in-hospital mortality and patient disposition and to compare the distribution of the risk of death associated with hyponatremia across the lifespan of hospitalized patients, we conducted an observational study of 2.3 million patients using data extracted from the Cerner Health Facts database between 2000 and 2014. Logistic regression models were used in the analyses.

Results

At hospital admission 14.4% of hospitalized patients had serum sodium levels [Na] <135 mEq/L. In adjusted multinomial logistic regression analysis, we found that the risk of in-hospital mortality significantly increases for [Na] levels < 135 or ≥143 to ≤145 mEq/L compared to the reference interval of 140 to <143 mEq/L (p<0.001). We observed similar trends for the relationship between [Na] levels and discharge to hospice or to a nursing facility. We demonstrated that younger age groups (18 to <45, 45 to <65) had a higher risk of in-hospital mortality compared to older age groups (65 to <75, ≥75) for [Na] levels <130 mEq/L or 143 to ≤145 mEq/L (p<0.001).

Conclusions

Hyponatremia is common among hospitalized patients and is significantly associated with in-hospital mortality, discharge to hospice or to a nursing facility. The risk of death and other outcomes was more evident for [Na] <135 mEq/L. The mortality associated with low [Na] was significantly higher in younger versus older patients.

Prevalence of hyponatremia in inpatients with incurable and life-limiting diseases and its association with physical symptoms-a retrospective descriptive study

PURPOSE

Hyponatremia is a common electrolyte abnormality seen in hospitalized patients. It may cause a variety of symptoms and is associated with longer hospitalizations and higher mortality. However, to date, only little is known about the extent of hyponatremia in patients with incurable diseases and whether it is associated with physical symptoms in this patient group. This study aims to describe the prevalence of hyponatremia, associated symptoms, and symptom intensity in inpatients with hyponatremia receiving specialist palliative care (SPC).

METHODS

This is a retrospective study. Demographic and clinical data as well as symptoms, scored symptom intensity, and laboratory values were collected. All inpatients of a large German University Hospital receiving SPC in 2013 with documented sodium values were included.

RESULTS

In 2013, 789 inpatients received SPC of which 710 had documented sodium values. The prevalence of hyponatremia was 38.7% (275/710). A mild degree showed 220 (31,0%), 44 (6.2%) had a moderate, and 11 (1.6%) a severe form. Hyponatremia patients experienced significantly more symptoms than normonatremic patients (mean = 7.71 vs 6.63; p < 0.001). Breathlessness, depressiveness, nausea, vomiting, poor appetite, constipation, and weakness were significantly more frequent in patients with hyponatremia. Furthermore, hyponatremia severity was associated with higher symptom intensity (mean = 13.29 vs 11.28; p < 0.001).

CONCLUSIONS

More than one third of all SPC patients showed a hyponatremia, and the hyponatremia grade was associated with symptom burden and symptom intensity. A prospective analysis is needed to further examine this association and the possible influence of hyponatremia correction on symptom burden reduction.

Prevalence of Hyponatremia and Its Associated Morbimortality in Hospitalized Patients Receiving Parenteral Nutrition

Background: The objective of the study was to determine the prevalence of hyponatremia (HN) and its associated morbimortality in hospitalized patients receiving parenteral nutrition (PN). Methods: A retrospective study including 222 patients receiving total PN (parenteral nutrition group [PNG]) over a 7-month period in a tertiary hospital and 176 matched to 179 control subjects without PN (control subjects group [CSG]). Demographic data, Charlson Comorbidity Index (CCI), date of HN detection-(serum sodium or SNa <135 mmol/L)-intrahospital mortality, and hospital length-of-stay (LOS) were registered. In the PNG, body mass index (BMI) and SNa before, during, and after PN were recorded. Results: HN was more prevalent in the PNG: 52.8 vs. 35.8% (p = 0.001), and independent of age, gender, or CCI (OR 1.8 [95% CI 1.1-2.8], p = 0.006). In patients on PN, sustained HN (75% of all intraindividual SNa <135 mmol/L) was associated with a higher mortality rate independent of age, gender, CCI, or BMI (OR 7.38 [95% CI 1.07-50.8], p = 0.042). The absence of HN in PN patients was associated with a shorter hospital LOS (<30 days) and was independent of other comorbidities (OR 3.89 [95% CI 2.11-7.18], p = 0.001). Conclusions: HN is more prevalent in patients on PN. Sustained HN is associated with a higher intrahospital mortality rate. Absence of HN is associated with a shorter hospital LOS.

Hyponatremia in Guillain-Barré Syndrome

OBJECTIVES

To evaluate incidence, risk factors, and in-hospital outcomes associated with hyponatremia in patients hospitalized for Guillain-Barré Syndrome (GBS).

METHODS

We identified adult patients with GBS in the Nationwide Inpatient Sample (2002-2011). Univariate and multivariable analyses were used.

RESULTS

Among 54,778 patients hospitalized for GBS, the incidence of hyponatremia was 11.8% (compared with 4.0% in non-GBS patients) and increased from 6.9% in 2002 to 13.5% in 2011 (P < 0.0001). Risk factors associated with hyponatremia in multivariable analysis included advanced age, deficiency anemia, alcohol abuse, hypertension, and intravenous immunoglobulin (all P < 0.0001). Hyponatremia was associated with prolonged length of stay (16.07 vs. 10.41, days), increased costs (54,001 vs. 34,125, $USD), and mortality (20.5% vs. 11.6%) (all P < 0.0001). In multivariable analysis, hyponatremia was independently associated with adverse discharge disposition (odds ratio: 2.07, 95% confidence interval, 1.91-2.25, P < 0.0001).

CONCLUSIONS

Hyponatremia is prevalent in GBS and is detrimental to patient-centered outcomes and health care costs. Sodium levels should be carefully monitored in high-risk patients.

Treatment of Cirrhosis-Associated Hyponatremia with Midodrine and Octreotide

BACKGROUND

Hyponatremia in the setting of cirrhosis is a common electrolyte disorder with few therapeutic options. The free water retention is due to non-osmotic vasopressin secretion resulting from the cirrhosis-associated splanchnic vasodilatation. Therefore, vasoconstrictive therapy may correct this electrolyte abnormality. The aim of this study was to assess the efficacy of midodrine and octreotide as a therapeutic approach to increasing urinary electrolyte-free water clearance (EFWC) in the correction of cirrhosis-associated hyponatremia.

METHODS

This observational study consisted of 10 patients with cirrhosis-associated hyponatremia. Hypovolemia was ruled out as the cause of the hyponatremia with a 48-h albumin challenge (25 g IV q6 h). Patients whose hyponatremia failed to improve with albumin challenge were started on midodrine and octreotide at 10 mg po tid and 100 μg sq tid, respectively, with rapid up-titration as tolerated to respective maximal doses of 15 mg tid and 200 μg tid within the first 24 h. We assessed urinary EFWC and serum sodium concentration before and 72 h after treatment.

RESULTS

Pretreatment serum sodium levels ranged from 119 to 133 mmol/L. The mean pretreatment serum sodium concentration ± SEM was 124 mmol/L ± 1.6 vs 130 mmol/L ± 1.5 posttreatment (p = 0.00001). The mean pretreatment urinary EFWC ± SEM was 0.33 L ± 0.07 vs 0.82 L ± 0.11 posttreatment (p = 0.0003).

CONCLUSION

Our data show a statistically significant increase in serum sodium concentration and urinary EFWC with the use of midodrine and octreotide in the treatment of cirrhosis-associated hyponatremia.

Long-term outcome of profound hyponatremia: a prospective 12 months follow-up study

BACKGROUND

Hyponatremia is the most common electrolyte abnormality in hospitalized patients and given its impact on mortality and morbidity, a relevant medical condition. Nevertheless, little is known about factors influencing long-term outcome.

METHODS

This is a prospective observational 12-month follow-up study of patients with profound hyponatremia (≤125 mmol/L) admitted to the emergency department of two tertiary care centers between 2011 and 2013. We analyzed the predictive value of clinical and laboratory parameters regarding the following outcomes: 1-year mortality, rehospitalization and recurrent profound hyponatremia.

RESULTS

Median (IQR) initial serum sodium (s-sodium) level of 281 included patients was 120 mmol/L (116-123). During the follow-up period, 58 (20.6%) patients died. The majority (56.2%) were rehospitalized at least once. Recurrent hyponatremia was observed in 42.7%, being profound in 16%. Underlying comorbidities, assessed by the Charlson Comorbidity Index, predicted 1-year mortality (odds ratio (OR) 1.43, 95% confidence interval (CI) 1.25-1.64, P < 0.001). Furthermore, 's-sodium level at admission' (OR 1.14, 95% CI 1.01-1.29, P = 0.036) and 'correction of hyponatremia' defined as s-sodium ≥135 mmol/L at discharge were associated with mortality (OR 0.47, 95% CI 0.23-0.94, P = 0.034). Mortality rate fell with decreasing baseline s-sodium levels and was lower in the hyponatremia category ≤120 mmol/L vs >120 mmol/L (14.8% and 27.8%, P < 0.01). Patients with s-sodium level ≤120 mmol/L were more likely to have drug-induced hyponatremia, whereas hypervolemic hyponatremia was more common in patients with s-sodium >120 mmol/L.

CONCLUSION

Hyponatremia is associated with a substantial 1-year mortality, recurrence and rehospitalization rate. The positive correlation of s-sodium and mortality emphasizes the importance of the underlying disease, which determines the outcome besides hyponatremia itself.

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

Background

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

Methods

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

Results

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

Conclusion

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