Clinical relevance of hyponatraemia for the hospital outcome of cirrhotic patients

Rapid correction rate of hyponatremia as an independent risk factor for neurological complication following liver transplantation

Hyponatremia is prevalent before liver transplantation and generally corrected immediately after transplantation. However, the clinical significance of correction rate of hyponatremia is not well investigated. The prognostic impact of pre-transplant serum sodium concentrations and post-transplant correction rate of hyponatremia were assessed. A total of 512 patients who received orthotopic liver transplants were enrolled. The correction rate of hyponatremia (delta sodium, ΔNa) was calculated based on the data collected during the first 48 hours following liver transplantation. Outcomes, including in-hospital mortality, delirium, neurological complications, acute kidney injury, and infections, were compared according to the serum sodium levels (sNa < 125, 125-135, and ≥ 135 mmol/L), and the risk factors for in-hospital mortality and neurological complications were analyzed using multivariate logistic regression methods. Patients with severe hyponatremia (sNa < 125 mmol/L) had higher rates of in-hospital mortality (9.6%, P = 0.010), delirium (54.8%, P = 0.003), neurological complications (24.7%, P = 0.003), and acute kidney injury (57.5%, P = 0.005). In multivariate analysis, serum sodium levels (OR = 0.975, P = 0.402) and delta sodium (OR = 1.097, P = 0.066) were not independent risk factors for in-hospital mortality. However, delta sodium (OR = 1.093, P = 0.003) and fast correction rate of hyponatremia (ΔNa ≥ 12 mmol/L/24h, OR = 3.397, P = 0.023) were significantly associated with post-transplant neurological complications. Pre-transplantation hyponatremia was not independently associated with clinical outcomes. However, rapid correction of hyponatremia is an independent risk factor for the development of post-transplant neurological complications.

Inflammation and hepatic encephalopathy

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome associated with both acute and chronic liver dysfunction, spanning a spectrum that ranges from mild neuropsychological disturbances to coma. The central role of ammonia in the pathogenesis of HE remains incontrovertible however, there is a robust evidence base indicating the important role of inflammation in exacerbating the neurological effects of HE. Inflammation can arise directly within the brain itself as a result of deranged nitrogen and energy homeostasis, with resultant neuronal, astrocyte and microglial dysfunction. Inflammation may also originate in the peripheral circulation and exert effects on the brain indirectly, via the release of pro-inflammatory mediators which directly signal to the brain via the vagus nerve. This review summarises the data that demonstrate the synergistic relationship of inflammation and ammonia that culminates in the manifestation of HE. Sterile inflammation arising from the inflamed or necrotic liver, circulating endotoxin arising from the gut (bacterial translocation) inducing immune dysfunction, and superimposed sepsis will be comprehensively discussed. Finally, this review will provide an overview of the existing and novel treatments on the horizon which can target the inflammatory response, and how they might translate into clinical practise as therapies in the prophylaxis and treatment of HE.

Hyponatremia and mortality: moving beyond associations

Acute hyponatremia can cause death if cerebral edema is not treated promptly. Conversely, if chronic hyponatremia is corrected too rapidly, osmotic demyelination may ensue, which also potentially is lethal. However, these severe complications of hyponatremia are relatively uncommon and often preventable. More commonly, hyponatremia predicts mortality in patients with advanced heart failure or liver cirrhosis. In these conditions, it generally is assumed that hyponatremia reflects the severity of the underlying disease rather than contributing directly to mortality. The same assumption holds for the recently reported associations between hyponatremia and mortality in patients with pulmonary embolism, pulmonary hypertension, pneumonia, and myocardial infarction. However, recent data suggest that chronic and mild hyponatremia in the general population also are associated with mortality. In addition, hyponatremia has been associated with mortality in long-term hemodialysis patients without residual function in whom the underlying disease cannot be responsible for hyponatremia. These new data raise the question of whether hyponatremia by itself can contribute to mortality or it remains a surrogate marker for other unknown risk factors. We review hyponatremia and mortality and explore the possibility that hyponatremia perturbs normal physiology in the absence of cerebral edema or osmotic demyelination.

Significance of hypo- and hypernatremia in chronic kidney disease

Both hypo- and hypernatremia are common conditions, especially in hospitalized patients and in patients with various comorbid conditions such as congestive heart failure or liver cirrhosis. Abnormal serum sodium levels have been associated with increased mortality in numerous observational studies. Patients with chronic kidney disease (CKD) represent a group with a high prevalence of comorbid conditions that could predispose to dysnatremias. In addition, the failing kidney is also characterized by a gradual development of hyposthenuria, and even isosthenuria, which results in further predisposition to the development of hypo- and hypernatremia in those with advancing stages of CKD. To date, there has been a paucity of population-wide assessments of the incidence and prevalence of dysnatremias, their clinical characteristics and the outcomes associated with them in patients with various stages of CKD. We review the physiology and pathophysiology of water homeostasis with special emphasis on changes occurring in CKD, the outcomes associated with abnormal serum sodium in patients with normal kidney function and the results of recent studies in patients with various stages of CKD, which indicate a substantial incidence and prevalence and significant adverse outcomes associated with dysnatremias in this patient population.

Hyponatremia, hypernatremia, and mortality in patients with chronic kidney disease with and without congestive heart failure

BACKGROUND

Hyponatremia is common in patients with conditions such as congestive heart failure and is associated with increased mortality in hospitalized patients. Congestive heart failure is common in patients with chronic kidney disease, but the association of serum sodium concentration with mortality in such patients is not well characterized.

METHODS AND RESULTS

We examined the association of serum sodium concentration with all-cause mortality in a nationally representative cohort of 655 493 US veterans with non-dialysis-dependent chronic kidney disease (95 961 [15%] of them with congestive heart failure). Associations were examined in time-dependent Cox models with adjustment for potential confounders. During a median follow-up of 5.5 years, a total of 193 956 patients died (mortality rate, 62.5/1000 patient-years; 95% confidence interval, 62.2-62.8). The association of serum sodium level with mortality was U-shaped, with the lowest mortality seen in patients with sodium level of 140 mEq/L and with both lower and higher levels showing significant associations with increased mortality. Patients with serum sodium levels of <130, 130 to 135.9, 145.1 to 150, and ≥150 mEq/L compared with 136 to 145 mEq/L had multivariable-adjusted mortality hazard ratios (95% confidence interval) of 1.93 (1.83-2.03), 1.28 (1.26-1.30), 1.33 (1.28-1.38), and 1.56 (1.33-1.83) (P<0.001 for all). The associations remained consistent in subgroups of patients with and without congestive heart failure.

CONCLUSIONS

Both lower and higher serum sodium levels are independently associated with higher mortality in patients with non-dialysis-dependent chronic kidney disease, irrespective of the presence or absence of congestive heart failure.

Heritability of serum sodium concentration: evidence for sex- and ethnic-specific effects

Serum sodium concentration is the clinical index of systemic water balance. Although disordered water balance is common and morbid, little is known about genetic effects on serum sodium concentration at the population level. Prior studies addressed only participants of European descent and either failed to demonstrate significant heritability or showed only modest effect. We investigated heritability of serum sodium concentration in large cohorts reflecting a range of races/ethnicities, including the Framingham Heart Study (FHS, non-Hispanic Caucasian), the Heredity and Phenotype Intervention Heart Study (HAPI, Amish Caucasian), the Jackson Heart Study (JHS, African American), the Strong Heart Family Study (SHFS, American Indian), and the Genetics of Kidney Disease in Zuni Indians Study (GKDZI, American Indian). Serum sodium was transformed for the osmotic effect of glucose, and participants with markedly elevated glucose or reduced estimated glomerular filtration rate (eGFR) were excluded. Using a standard variance components method, incorporating covariates of age, glucose, and eGFR, we found heritability to be high in African American and American Indian populations and much more modest in non-Hispanic Caucasian populations. Estimates among females increased after stratification on sex and were suggestive among female participants in FHS (0.18 ± 0.12, P = 0.057) and male participants in JHS (0.24 ± 0.16, P = 0.067) and statistically significant among female participants in JHS (0.44 ± 0.09, P = 1 × 10 ⁻⁷), SHFS (0.59 ± 0.05, P = 9.4 × 10⁻⁴⁶), and GKDZI (0.46 ± 0.15, P = 1.7 × 10⁻⁴), and male participants in HAPI (0.18 ± 0.12, P = 0.03) and SHFS (0.67 ± 0.07, P = 5.4 × 10⁻²⁶). Exclusion of diuretic users increased heritability among females and was significant in all cohorts where data were available. In aggregate, these data strongly support the heritability of systemic water balance and underscore sex and ethnicity-specific effects.

Hyponatremia in hospitalized patients: the potential role of tolvaptan

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

Conivaptan: a step forward in the treatment of hyponatremia?

Hyponatremia is one of the most common electrolyte abnormalities linked to adverse outcomes and increased mortality in hospitalized patients. While the differential diagnosis for hyponatremia is diverse, most cases stem from arginine vasopressin (AVP) dysregulation, where hypoosmolality fails to suppress AVP synthesis and release. The physiological effects of AVP are currently known to depend on its interaction with any of 3 receptor subtypes V1A, V2, and V1B. Activation of V2 by AVP is the key in renal water regulation and maintenance of total body volume and plasma tonicity. Despite the long-recognized problem with excess AVP in euvolemic and hypervolemic hyponatremia, traditional therapeutic options have relied on nonspecific and potentially problematic strategies. More recently, a new class of drugs, introduced as “aquaretics,” has gained great attention among clinicians because of its ability to correct hyponatremia via direct competitive inhibition of AVP at V2 receptors to induce renal electrolyte-free water excretion. In this paper, we aim to review available clinical data on the only FDA-approved aquaretic, dual V1A/V2 receptor antagonist conivaptan, discuss its clinical indications, efficacy, safety profile, and comment on its clinical limitations.

Profile of hepatic encephalopathy in children with cirrhosis and response to lactulose

BACKGROUND/AIM

Hepatic encephalopathy (HE) is associated with a poor prognosis. There is paucity of data on the treatment of HE with lactulose in children with cirrhosis.

PATIENTS AND METHODS

Retrospective analysis of consecutive cirrhotic patients (<18 years) with HE was done. HE was defined according to West-Haven criteria. Response was defined as complete if patients recovered completely from HE, partial response was defined as improvement of encephalopathy by one or more grades from admission but not complete recovery, and defined as non response if patient did not show any improvement or deteriorated further even after 10 days of lactulose therapy.

RESULTS

A total of 300 patients were admitted with cirrhosis and HE (278 adults and 22 children). Of 22 patients, 16 (73%) patients had complete response to lactulose and six (27%) patients did not [three (13.5%) patients worsened (non response) and three (13.5%) did not recover fully even after 10 days of treatment (partial response)]. Comparing baseline characteristics of patients who had complete response (n=16) versus partial (n=3) and non response (n=3), there was significant difference in mean arterial pressure (78.1±10.7 vs 62.6±5.0 mmHg, P=0.003), serum sodium (131.3±3.2 vs 126.5±5.2, P=0.01) and serum creatinine (0.78±0.3 vs 1.1±0.3 mg/dl, P=0.02). We did not find any difference in baseline characteristics of these patients regarding CTP score (9.6±1.2 vs 10.6±1.2), MELD score (17.6±2.9 vs 17.1±3.4), severity of HE (2.5±0.6 vs 2.6±0.5) and etiology of precipitating factors (P=0.78).

CONCLUSIONS

Lactulose therapy causes complete recovery from hepatic encephalopathy in 73% of pediatrics patients with cirrhosis.

Managing hyponatremia in cirrhosis

The development of hyponatremia represents an ominous event in the progression of cirrhosis to end-stage liver disease. It usually develops in those with refractory ascites and is a manifestation of the non-osmotic release of arginine vasopressin (AVP). In the hospitalized cirrhotic patient, hyponatremia is associated with increased disease severity and mortality. In this article, we review the pathophysiology of hyponatremia, its clinical implications, evaluation, and treatment.

Predictors of nonresponse to lactulose in patients with cirrhosis and hepatic encephalopathy

BACKGROUND AND AIMS

Lactulose is commonly used in the treatment of hepatic encephalopathy (HE). However, all patients do not respond to lactulose. We evaluated predictors of nonresponse to lactulose in patients with cirrhosis and HE.

PATIENTS AND METHODS

Consecutive cirrhotic patients with HE were enrolled. HE was diagnosed by West Haven criteria. Patients were treated with lactulose and correction of any associated precipitating factors. Nonresponse was defined if patient remained in HE even after 10 days of treatment or died while in HE.

RESULTS

Of 300 patients with cirrhosis and HE, 231 (77%) patients met the inclusion criteria. The majority (95%) of the patients had Grade 2 or 3 HE. Of 231 patients, 180 (78%) responded to lactulose. Fifty-one (22%) did not respond to lactulose, 34 (15%) died without any improvement in HE and HE did not improve in 17 (7%) patients after 10 days of therapy. On comparing baseline parameters between nonresponders versus responders there was significant difference between baseline age (42.0+/-11.9 vs. 46.6+/-12.7 year, P=0.02), total leukocyte count (median, 9300 vs. 7300 cells/mm3, P=0.001), serum sodium level (129.9+/-6.2 vs. 133.7+/-7.1 mmol/l, P=0.001), model for end stage liver disease (MELD) score (22.9+/-3.8 vs. 19.9+/-4.2, P=0.001), mean arterial pressure (MAP, 77.9+/-10.0 vs. 86.3+/-8.7 mmHg, P=0.001), serum AST (median, 114 vs. 76 IU/l, P=0.01), serum ALT (median, 84 vs. 48.5 IU/l, P=0.001), spontaneous bacterial peritonitis [18 (35%) vs. 37 (21%), P=0.02] and hepatocellular carcinoma [HCC, 17 (33%) vs. 14 (7%), P=0.001]. On multivariate analysis baseline total leukocyte count, MELD, MAP, and HCC were independent predictors of nonresponse to lactulose (P=0.001). Combination of low MAP, high MELD, and presence of HCC had diagnostic accuracy of 81% in predicting nonresponse to lactulose.

CONCLUSION

Of 78% patients with chronic liver disease with HE (majority with Grade 2 and 3) responded to lactulose. High baseline MELD, high total leukocyte count, low serum sodium, low MAP, and presence of hepatocellular carcinoma were predictors of nonresponse to lactulose.

Hyponatremia in cirrhosis and vaptans

Hyponatremia is a common problem in patients with advanced cirrhosis. Hyponatremia in cirrhosis includes two distinct types: hypovolemic hyponatremia, and hypervolemic or dilutional hyponatremia. The former is characterized by low blood sodium, low blood volume, dehydration and prerenal renal dysfunction, not accompanied by edema and ascites, while the latter is characterized by insufficient circulatory volume and dilutional hyponatremia, accompanied by edema and ascites. Hyponatremia is closely related to various complications of cirrhosis and to early mortality after liver transplantation. Vaptans, a class of selective non-peptide arginine vasopressin (AVP) receptor antagonists, act by antagonizing specifically the effects of AVP V₂ receptor located in the renal collecting tubules to inhibit water reabsorption without affecting electrolytes excretion. Vaptans has been evaluated by several clinical trials for their role in the management of hyponatremia. The short-term treatment with vaptans is associated with a marked increase in renal solute-free water excretion and improvement of hyponatremia with no apparent adverse reactions. The discovery of vaptans is considered a new milestone in the management of hyponatremia in cirrhosis.

Hyponatremia increases mortality in pediatric patients listed for liver transplantation

To evaluate hyponatremia as an independent predictor of mortality in pediatric patients with end-stage liver disease listed for transplantation. We performed a single-center retrospective study of children listed for liver transplantation. We defined hyponatremia as a serum sodium concentration <130 mEq/L that persisted for at least seven days. The primary outcome was death on the waiting list. Ninety-four patients were eligible for the study. The prevalence of hyponatremia was 26%. Kaplan-Meier survival analysis demonstrated that patients with hyponatremia had decreased pretransplant survival compared with patients who maintained a serum sodium >130 mEq/L (p < 0.001). Univariable association analyses demonstrated death on the waiting list was also associated with higher median PELD scores at listing (p = 0.01), non-white race (p = 0.02), and age <1 yr (p = 0.001). Logistic regression analysis identified hyponatremia and non-white race as independently associated with pretransplant mortality [OR = 8.0 (95% CI: 1.4-45.7), p = 0.02 and OR = 6.3 (95% CI: 1.25-33.3), p = 0.03]. When hyponatremia was added to the PELD score, it was significantly better in predicting mortality than the PELD score alone (c-statistic = 0.79, p = 0.03). Hyponatremia identifies a subset of pediatric patients with increased risk of pretransplant mortality and improves the predictive ability of the current PELD score.

Comparison of the model for end-stage liver disease (MELD), MELD-Na and MELDNa for outcome prediction in patients with acute decompensated hepatitis

BACKGROUND AND AIM

The model for end-stage liver disease (MELD) is used to predict the outcome of patients with cirrhosis. Incorporation of serum sodium (Na) into MELD may further increase its prognostic ability. Two Na-containing MELD models, MELD-Na and MELDNa, were proposed to enhance the prognostic ability. This study compared the predictive accuracy of these models for acute decompensated hepatitis.

METHODS

We investigated the outcome of 182 patients with acute decompensated hepatitis.

RESULTS

Twenty (11%) patients died at 3 months. The MELD-Na and MELDNa both had significantly higher area under the receiver operating characteristic curve (AUC) in comparison to MELD (MELD-Na: 0.908, MELDNa: 0.895, MELD: 0.823, p=0.004 and 0.001, respectively). Among 96 patients without specific antiviral treatment, the MELD-Na and MELDNa consistently had significantly higher AUC than the MELD (MELD-Na: 0.901, MELDNa: 0.882, MELD: 0.810, p=0.008 and 0.004, respectively). Three independent indicators, pre-existing cirrhosis (odds ratio [OR]: 5.67, 95% confidence interval [CI]: 1.72-18.7), serum albumin<3.7 g/dL (OR: 5.68, 95% CI: 1.18-27.03) and serum sodium (Na)<138 mequiv./L (OR: 10.0, 95% CI: 2.08-47.62), were associated with 3-month mortality.

CONCLUSION

MELD-Na and MELDNa provide better prognostic accuracy than the MELD for patients with acute decompensated hepatitis. The adequacy of liver reserve determines the outcome of these patients.

Allocation priority in non-urgent liver transplantation: An overview of proposed scoring systems

Given the lack of donors, a correct organ allocation system for candidates to liver transplantation is essential to increase graft and patient survival. The most used organ allocation tools are Child-Turcotte-Pugh and model for end-stage liver disease. It is generally accepted that model for end-stage liver disease score is superior to the Child-Turcotte-Pugh classification in predicting the short-term survival of cirrhotic patients awaiting liver transplantation. Since 2002, model for end-stage liver disease is widely used for liver allocation. In recent years, to overcome limitations of the consolidated scores, some adjustments to the original model for end-stage liver disease formula and new scoring systems have been proposed. Published data suggest that integrating serum sodium and model for end-stage liver disease may improve the score prognostic accuracy but further studies are necessary to confirm this issue. The updated model for end-stage liver disease, obtained through a revision of traditional model for end-stage liver disease parameters and tested in a large cohort of patients, is of great interest at the moment. In conclusion, several scoring systems have been described for organ allocation, but today, none is definitely able to overcome the limitations of the Child-Turcotte-Pugh and model for end-stage liver disease systems.

Predictors of nonresponse to lactulose for minimal hepatic encephalopathy in patients with cirrhosis

BACKGROUND/AIMS

Minimal hepatic encephalopathy (MHE) impairs health-related quality of life and predicts overt hepatic encephalopathy (HE) in cirrhotic patients. Lactulose is effective in the treatment of MHE. However, not all patients respond to lactulose. We evaluated predictors of nonresponse to lactulose.

PATIENTS AND METHODS

Consecutive 110 cirrhotic patients without HE were evaluated for MHE by psychometry, P300 auditory event-related potential (P300ERP), venous ammonia and critical flicker frequency (CFF). MHE was diagnosed by abnormal psychometry and P300ERP (>2 SD). MHE patients were treated with lactulose for 1 month. Response was defined by normalization of the abnormal test parameters (both psychometric tests and P300ERP).

RESULTS

Sixty patients (54.5%) were diagnosed as having MHE: 17/39 (44%) in Child's A, 21/42 (50%) Child's B and 22/29 (76%) in Child's C. There was a significant difference between Child's C's vs Child's A's and B's (P<0.05). Abnormal psychometric tests and abnormal P300ERP were seen in 74 (67%) and 74 (67%) patients respectively. Of 60 patients with MHE, after treatment, psychometry remained abnormal in 22 (36.6%) and P300ERP in 21 (35%) patients. CFF was<38 Hz in 34 (57%) and 11 (18%) patients, respectively, before and after treatment in MHE patients. There was a significant difference between the baseline serum sodium level (134.7+/-2.6 vs 131.1+/-2.2 mmol/L, P=0.001) and the venous ammonia level (76.6+/-20.7 vs 113.4+/-22.8 micromol/L, P=0.001) between responders vs nonresponders. Receiver operating characteristic analysis was performed to identify the cutoff for venous ammonia [cutoff 93.5 mmol/L, area under the curve (AUC) 0.892 (0.814-0.970)] and for the serum sodium level [cutoff 132.5 mmol/L, AUC 0.874 (0.779-0.998)]. Taking a cutoff of 93.5 mmol/L for ammonia patient had a sensitivity of 88.5% and a specificity of 79.4%, respectively, and a cutoff of 132.5 mmol/L for serum sodium patient had a sensitivity of 76.5% and a specificity of 88.5% for nonresponse to lactulose. On univariate analysis and multivariate analysis, serum sodium and venous ammonia were the only two parameters associated with nonresponse to lactulose.

CONCLUSION

The prevalence of MHE was 55% and MHE improved in 57% patients with lactulose. Baseline low serum sodium and high venous ammonia were highly predictive of nonresponse to lactulose therapy.

Validation of model for end-stage liver disease score to serum sodium ratio index as a prognostic predictor in patients with cirrhosis

AIM

To evaluate the prognostic ability of model for end-stage liver disease (MELD) to serum sodium (SNa) ratio (MESO) index and to compare the predictive accuracy of the MESO index with the MELD score and the modified Child-Turcotte-Pugh (CTP) score for short-term survival in cirrhotic patients.

METHODS

A total of 256 patients with cirrhosis were retrospectively evaluated. The predictive accuracy of the MESO index, MELD score and modified CTP score were compared by the area under the receiver-operator characteristic curve (AUC).

RESULTS

Using 1-month and 3-month mortality as the end-point, overall, MESO and MELD were significantly better than the CTP score in predicting the risk of mortality at 1 month (AUC, 0.866,0.819 vs 0.722, P < 0.01) and 3 months (AUC, 0.875,0.820 vs 0.721, P < 0.01). In the low MELD group, the AUC of MESO index (0.758, 0.759) and CTP score (0.754, 0.732) were higher than that of the MELD score (0.608, 0.611) at 1 month and 3 months, respectively (P < 0.01). However, in the high MELD group, the AUC of MESO index (0.762, 0.779) and MELD (0.737, 0.773) were higher than that of the CTP score (0.710, 0.752) at 1 month and 3 months, respectively, although there were no significant differences (P > 0.05). With appropriate cut-offs for the MESO index, the mortality rate of patients in high MESO was higher (57.1% at 1 month and 69.2% at 3 months) than that of the low MESO (5.5% at 1 month and 7.9% at 3 months) (P < 0.01).

CONCLUSIONS

The MESO index, which adds SNa to MELD, is a useful prognostic marker and is found to be superior to the MELD score and modified CTP score for short-term prognostication of patients with cirrhosis.

Epidemiology of hyponatremia

Hyponatremia is the most common electrolyte abnormality encountered in clinical practice with wide-ranging prognostic implications in a variety of conditions. This review summarizes the available literature on the epidemiology of hyponatremia in both hospitalized and ambulatory-based patients. Particular attention is given to hyponatremia in the geriatric population, drug-induced hyponatremia, exercise-associated hyponatremia, and the medical costs of hyponatremia. The frequency and outcomes of hyponatremia in congestive heart failure, cirrhosis, pneumonia, and human immunodeficiency virus infection also are reviewed. Although the knowledge on hyponatremia has expanded in the past few decades, the disorder largely remains an underdiagnosed condition. Substantial additional work is needed to improve the awareness of hyponatremia among medical professionals. The advent of vasopressin-receptor antagonists as a plausible treatment option for some forms of euvolemic and hypervolemic hyponatremia now offers the opportunity to gain further insights into the prognostic impact of hyponatremia and its management in various clinical settings.

Outcome of patients with hepatorenal syndrome type 1 after liver transplantation: Hangzhou experience

BACKGROUND

Patients with hepatorenal syndrome (HRS) type 1 have an extremely poor prognosis. Liver transplantation (LT) is the only treatment that can cure terminal stage liver disease and reverse HRS. However, the data showing the impact of LT on patients with HRS type 1 are limited.

METHODS

The outcome and prognostic factors of 32 patients with HRS type 1 receiving LT were investigated. The natural course of renal recovery and the efficacy of continuous post-LT veno-veno hemodialysis (CVVH) were also evaluated.

RESULTS

Overall patient mortality was 34.4% (11/32), with eight patients died during the first month after LT. Scoring model was based on independent prognostic factors for the model end-stage liver diseases (MELD) (risk ratio=1.169) and serum sodium (risk ratio=0.769). High MELD score (>36) or low serum sodium (< or =126 mEq/L) or both were associated with reduced patient survival. HRS was resolved in 30 patients (median time, 24 days). Eight patients received post-LT CVVH. The need for CVVH was associated with higher pretransplant serum creatinine, longer duration of HRS, more pretransplant CVVH, more intraoperative blood products infusion, lower intraoperative urine output, and higher serum creatinine at 1 week posttransplant. However, serum creatinine at 1 month posttransplant and patient survival did not differ significantly between patients with and without CVVH.

CONCLUSION

Patients developing HRS type 1 in the absence of high MELD score and low serum sodium would benefit from LT.

The association between the serum sodium level and the severity of complications in liver cirrhosis

BACKGROUND/AIMS

Dilutional hyponatremia associated with liver cirrhosis is caused by impaired free water clearance. Several studies have shown that serum sodium levels correlate with survival in cirrhotic patients. Little is known, however, regarding the relationship between the degree of dilutional hyponatremia and development of cirrhotic complications. The aim of this study was to evaluate the association between the serum sodium level and the severity of complications in liver cirrhosis.

METHODS

Data of inpatients with cirrhotic complications were collected retrospectively. The serum sodium levels and severity of complications of 188 inpatients were analyzed.

RESULTS

The prevalence of dilutional hyponatremia, classified as serum sodium concentrations of <or=135 mmol/L, <or=130 mmol/L, and <or=125 mmol/L, were 20.8%, 14.9%, and 12.2%, respectively. The serum sodium level was strongly associated with the severity of liver function impairment as assessed by Child-Pugh and MELD scores (p<0.0001). Even a mild hyponatremia with a serum sodium concentration of 131-135 mmol/L was associated with severe complications. Sodium levels less than 130 mmol/L indicated the existence of massive ascites (OR, 2.685; CI, 1.316-5.477; p=0.007), grade III or higher hepatic encephalopathy (OR, 5.891; CI, 1.490-23.300; p=0.011), spontaneous bacterial peritonitis (OR, 2.562; CI, 1.162-5.653; p=0.020), and hepatic hydrothorax (OR, 5.723; CI, 1.889-17.336; p=0.002).

CONCLUSIONS

Hyponatremia, especially serum levels <or=130 mmol/L, may indicate the existence of severe complications associated with liver cirrhosis.

Hyponatremia in hepatic encephalopathy: an accomplice or innocent bystander?

Hyponatremia, a common complication inpatients with advanced liver disease and impaired free water clearance, has been shown to be an important predictor of short-term mortality. Hepatic encephalopathy, also a late complication of end-stage liver disease, has been associated with low-grade cerebral edema as a result of swelling of astrocytes. Guevara et al. hypothesized that hyponatremia and the resultant depletion of organic osmolytes (e.g.,myo-inositol) from brain cells contribute to brain edema, playing an important role in the pathogenesis of hepatic encephalopathy. Using a multivariable analysis, they demonstrated that hyponatremia increased the risk of hepatic encephalopathy more than eightfold, after adjustment for serum bilirubin and creatinine concentrations and previous history of encephalopathy. Their magnetic resonance spectroscopy data correlated low brain concentrations of myoinositol with hepatic encephalopathy. As both hyponatremia and encephalopathy occur in patients with advanced liver disease, it has been difficult to implicate hyponatremia independently in the pathogenesis of hepatic encephalopathy. Guevara's data do suggest that hyponatremia is more likely an accomplice than an innocent bystander.

Value of the model for end-stage liver disease for predicting survival in hepatocellular carcinoma patients treated with transarterial chemoembolization

OBJECTIVE

The aim of this study was to evaluate the prognostic value of the model for end-stage liver disease (MELD) and its modified forms, and to compare these scoring systems with other staging systems for hepatocellular carcinoma (HCC) patients treated with transarterial chemoembolization (TACE).

MATERIAL AND METHODS

A total of 325 patients who underwent TACE for the initial treatment of HCC between January 2000 and May 2007 were enrolled in the study. Before TACE was carried out, MELD, MELD-Na, Child-Pugh score, Okuda stage, CLIP score, JIS score, BCLC stage, and UICC stage were checked. After one month, delta MELD and delta MELD-Na were calculated.

RESULTS

Mean MELD/MELD-Na/delta MELD/delta MELD-Na scores were 7.5+/-3.7, 8.0+/-4.7, -0.2+/-3.5 and 0.04+/-4.5, respectively. MELD (p=0.009) and MELD-Na (p=0.017) significantly correlated with survival, but delta MELD and delta MELD-Na did not (p >0.05). The Child-Pugh score and other staging systems correlated significantly with survival (p <0.05). The AUROC values for 3, 12, and 36 months' survival were 0.633, 0.545, and 0.615 for MELD; 0.655, 0.555, and 0.612 for MELD-Na; 0.639, 0.616, and 0.691 for Child-Pugh score; 0.714, 0.662, and 0.717 for the Okuda score; 0.837, 0.86, and 0.792 for the CLIP score; 0.859, 0.814, and 0.808 for the JIS score; 0.846, 0.833, and 0.749 for BCLC stage; and 0.878, 0.812, and 0.735 for UICC stage, respectively.

CONCLUSIONS

MELD and MELD-Na showed good correlations with survival, especially for patients with early-stage disease. However, these were not superior to those of other staging systems or Child-Pugh score. These parameters should only be used as supportive data.

Impact of pretransplant hyponatremia on outcome following liver transplantation

Hyponatremia is associated with reduced survival in patients with cirrhosis awaiting orthotopic liver transplantation (OLT). However, data are sparse regarding the impact of hyponatremia on outcome following OLT. We investigated the effect of hyponatremia at the time of OLT on mortality and morbidity following the procedure. The study included 2,175 primary OLT recipients between 1990 and 2000. Serum sodium concentrations obtained immediately prior to OLT were correlated with subsequent survival using proportional hazards analysis. Morbidity associated with hyponatremia was assessed, including length of hospitalization, length of intensive care unit (ICU) admission, and occurrence of central pontine myelinolysis (CPM). Out of 2,175 subjects, 1,495 (68.7%) had normal serum sodium (>135 mEq/L) at OLT, whereas mild hyponatremia (125-134 mEq/L) was present in 615 (28.3%) and severe hyponatremia (<125 mEq/L) in 65 (3.0%). Serum sodium had no impact on survival up to 90 days after OLT (multivariate hazard ratio = 1.00, P = 0.99). Patients with severe hyponatremia tended to have a longer stay in the ICU (median = 4.5 days) and hospital (17.0 days) compared to normonatremic recipients (median ICU stay = 3.0 days, hospital stay = 14.0 days; P = 0.02 and 0.08, respectively). There were 10 subjects that developed CPM, with an overall incidence of 0.5%. Although infrequent, the incidence of CPM did correlate with serum sodium levels (P < 0.01).

CONCLUSION

Pre-OLT serum sodium does not have a statistically significant impact on survival following OLT. The incidence of CPM correlates with hyponatremia, although its overall incidence is low. Incorporation of serum sodium in organ allocation may not adversely affect the overall post-OLT outcome.

Economic impact of hyponatremia in hospitalized patients: a retrospective cohort study

BACKGROUND

Hyponatremia is the most common electrolyte abnormality seen in general hospital patients, with an incidence of 1% to 6% in the United States.

OBJECTIVE

We aimed to evaluate the impact of varying levels of hyponatremia at admission on length of stay (LOS) and cost of care in adult hospitalized patients.

METHODS

A retrospective cohort study was conducted using an existing clinical database from a large academic-setting hospital. All adult admissions from January 2004 through May 2005 with serum sodium level at admission of < or = 134 mEq/L were separated into 2 cohorts: patients with moderate-to-severe hyponatremia (serum sodium level at admission of < or = 129 mEq/L, n = 547) and patients with mild-to-moderate hyponatremia (serum sodium level of 130-134 mEq/L, n = 1500). ICD-9 diagnosis codes for these 2047 admissions with hyponatremia were used to identify a cohort of 7573 admissions with the same principal admitting diagnoses and a serum sodium level of 135 to 145 mEq/L. Differences in hospital LOS, intensive care unit (ICU) admission rate, and median total costs per admission between cohorts were examined using multiple linear regression, logistic, and quantile regression models.

RESULTS

Admissions with hyponatremia had significantly longer hospital LOS than those admitted without hyponatremia (median LOS: moderate-to-severe hyponatremia, 8 days; mild-to-moderate hyponatremia, 8 days; normal, 6 days; P < 0.001). Patients with more severe hyponatremia were also more likely to be admitted to the ICU during the hospital stay (moderate-to-severe hyponatremia, 32%; mild-to-moderate hyponatremia, 26%; normal, 22%; P < 0.001). These trends were also reflected in the total costs per admission, with median costs of $16,606 for moderate-to-severe hyponatremia cases, $14,266 for mild-to-moderate hyponatremia cases, and $13,066 for normal admissions (P < 0.001).

CONCLUSIONS

Hyponatremia at admission was associated with increased LOS and cost of care for hospitalized patients. Interventions or pharmacotherapies for the prompt treatment of hyponatremia could potentially reduce morbidity and LOS, thereby reducing the utilization of health care resources.

Clinically relevant differences in the model for end-stage liver disease and model for end-stage liver disease-sodium scores determined at three university-based laboratories of the same area

The Model for End-Stage Liver Disease (MELD) score is considered an objective and reliable measure of liver disease severity. However, the use of specific laboratory methodologies may introduce significant and clinically relevant variations into the score. It has been suggested that the incorporation of sodium into MELD (MELD-Na) can provide a more accurate survival prediction than MELD alone. Before implementing organ allocation based on the MELD score in an area with 3 transplant centers, we studied whether there were significant variations in MELD and MELD-Na scores determined at each center. Seventy patients on the waiting list were studied simultaneously. Blood samples for each patient were divided into 3 aliquots and were processed in the 3 laboratories in order to calculate MELD and MELD-Na scores. There were statistical differences between the 3 laboratories in the MELD and MELD-Na scores and their parameters. The MELD score was identical in the 3 laboratories for only 6 of the 70 patients, and the MELD-Na score was identical for only 9. MELD and MELD-Na scores from 2 laboratories differed by 1 point or more in 54% and 47% of cases, respectively. Our study confirms that there is major variability in the MELD score, serum sodium, and MELD-Na score. These differences are clinically relevant, and in order to guarantee equitable organ allocation based on the MELD score, similar laboratory methodologies should be implemented at all centers in the same organ procurement area. Alternatively, the possibility of setting up a central laboratory in each organ procurement area should be considered.

The MELD-Na is an independent short- and long-term prognostic predictor for hepatocellular carcinoma: a prospective survey

BACKGROUND AND AIM

Serum sodium has been suggested to incorporate into the model for end-stage liver disease to enhance its prognostic ability for cirrhosis. A mathematical equation based on model for end-stage liver disease and sodium, known as "MELD-Na", was developed for outcome prediction for cirrhosis. The severity of liver cirrhosis is a key component to predict survival in patients with hepatocellular carcinoma. This study investigated the prognostic role of MELD-Na for hepatocellular carcinoma.

PATIENTS AND METHODS

A total of 535 unselected hepatocellular carcinoma patients were prospectively enrolled to evaluate the performance of MELD-Na.

RESULTS

The MELD-Na was better than model for end-stage liver disease in predicting 6-month mortality by comparing the area under receiver operating characteristic curve (0.782 vs. 0.761, p=0.101). MELD-Na, but not model for end-stage liver disease, was an independent predictor associated with 6-month mortality in multivariate logistic regression analysis (odds ratio: 1.14, p=0.001). In the survival analysis, MELD-Na also independently predicted mortality, with an additional risk of 4.3% per unit increment of the score (p<0.001). Patients with MELD-Na scores between 10 and 20 and scores >20 had 2.1-fold (p<0.001) and 7.5-fold (p<0.001) risk of mortality, respectively, compared to patients with a score <10 in the Cox proportional hazard model.

CONCLUSION

The MELD-Na score is a feasible and independent prognostic predictor for both short- and long-term outcome predictions in patients with hepatocellular carcinoma.

Ammonia impairs neutrophil phagocytic function in liver disease

Hyperammonemia is a feature of liver failure, which is associated with increased risk of infection. The aims of the present study were to determine in vitro, in rats fed an ammoniagenic diet and in patients with cirrhosis, whether induction of hyperammonemia results in neutrophil dysfunction. As hyperammonemia produces cell swelling, we explored the role of the osmoregulating, p38 mitogen-activated protein kinase (p38(MAPK)) pathway in mediating this neutrophil dysfunction. Neutrophils were isolated from blood of healthy volunteers and incubated with either 75 microM ammonia or phosphate-buffered saline. Both groups were studied under hyponatremic conditions and/or with the addition of p38(MAPK) modulators. Neutrophil phagocytosis was measured in naive rats and rats fed an ammoniagenic diet and in patients with stable cirrhosis given placebo (n = 8) or an amino acid solution inducing hyperammonemia (n = 8). Cell volume and phagocytosis was analyzed by fluorescent-activated cell sorting using fluorescein isothiocyanate-labeled E. coli. p38(MAPK) phosphorylation was measured by western blotting. In healthy neutrophils incubated with ammonia and in rats fed an ammoniagenic diet, neutrophils showed evidence of swelling, impaired phagocytosis, and increased spontaneous oxidative burst compared to controls. Phagocytosis was significantly impaired in patients with induced hyperammonemia compared to placebo. The effects of hyperammonemia and hyponatremia were synergistic. The p38(MAPK) intracellular signaling pathways were activated in healthy neutrophils exposed to ammonia in association with increased burst activity. Neutrophil phagocytic dysfunction was abrogated by the addition of a p38(MAPK) agonist.

CONCLUSION

Ammonia produces neutrophil swelling and impairs neutrophil phagocytosis. The p38(MAPK) intracellular signaling pathway has been shown to be important in mediating the ammonia-induced neutrophil dysfunction.

Hyponatremia and mortality among patients on the liver-transplant waiting list

BACKGROUND

Under the current liver-transplantation policy, donor organs are offered to patients with the highest risk of death.

METHODS

Using data derived from all adult candidates for primary liver transplantation who were registered with the Organ Procurement and Transplantation Network in 2005 and 2006, we developed and validated a multivariable survival model to predict mortality at 90 days after registration. The predictor variable was the Model for End-Stage Liver Disease (MELD) score with and without the addition of the serum sodium concentration. The MELD score (on a scale of 6 to 40, with higher values indicating more severe disease) is calculated on the basis of the serum bilirubin and creatinine concentrations and the international normalized ratio for the prothrombin time.

RESULTS

In 2005, there were 6769 registrants, including 1781 who underwent liver transplantation and 422 who died within 90 days after registration on the waiting list. Both the MELD score and the serum sodium concentration were significantly associated with mortality (hazard ratio for death, 1.21 per MELD point and 1.05 per 1-unit decrease in the serum sodium concentration for values between 125 and 140 mmol per liter; P<0.001 for both variables). Furthermore, a significant interaction was found between the MELD score and the serum sodium concentration, indicating that the effect of the serum sodium concentration was greater in patients with a low MELD score. When applied to the data from 2006, when 477 patients died within 3 months after registration on the waiting list, the combination of the MELD score and the serum sodium concentration was considerably higher than the MELD score alone in 32 patients who died (7%). Thus, assignment of priority according to the MELD score combined with the serum sodium concentration might have resulted in transplantation and prevented death.

CONCLUSIONS

This population-wide study shows that the MELD score and the serum sodium concentration are important predictors of survival among candidates for liver transplantation.

Hyponatremia and mortality among patients on the liver-transplant waiting list

BACKGROUND

Under the current liver-transplantation policy, donor organs are offered to patients with the highest risk of death.

METHODS

Using data derived from all adult candidates for primary liver transplantation who were registered with the Organ Procurement and Transplantation Network in 2005 and 2006, we developed and validated a multivariable survival model to predict mortality at 90 days after registration. The predictor variable was the Model for End-Stage Liver Disease (MELD) score with and without the addition of the serum sodium concentration. The MELD score (on a scale of 6 to 40, with higher values indicating more severe disease) is calculated on the basis of the serum bilirubin and creatinine concentrations and the international normalized ratio for the prothrombin time.

RESULTS

In 2005, there were 6769 registrants, including 1781 who underwent liver transplantation and 422 who died within 90 days after registration on the waiting list. Both the MELD score and the serum sodium concentration were significantly associated with mortality (hazard ratio for death, 1.21 per MELD point and 1.05 per 1-unit decrease in the serum sodium concentration for values between 125 and 140 mmol per liter; P<0.001 for both variables). Furthermore, a significant interaction was found between the MELD score and the serum sodium concentration, indicating that the effect of the serum sodium concentration was greater in patients with a low MELD score. When applied to the data from 2006, when 477 patients died within 3 months after registration on the waiting list, the combination of the MELD score and the serum sodium concentration was considerably higher than the MELD score alone in 32 patients who died (7%). Thus, assignment of priority according to the MELD score combined with the serum sodium concentration might have resulted in transplantation and prevented death.

CONCLUSIONS

This population-wide study shows that the MELD score and the serum sodium concentration are important predictors of survival among candidates for liver transplantation.

Sensitivity of International Classification of Diseases codes for hyponatremia among commercially insured outpatients in the United States

Background

Administrative claims are a rich source of information for epidemiological and health services research; however, the ability to accurately capture specific diseases or complications using claims data has been debated. In this study, the authors examined the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes for the identification of hyponatremia in an outpatient managed care population.

Methods

We analyzed outpatient laboratory and professional claims for patients aged 18 years and older in the National Managed Care Benchmark Database from Integrated Healthcare Information Services. We obtained all claims for outpatient serum sodium laboratory tests performed in 2004 and 2005, and all outpatient professional claims with a primary or secondary ICD-9-CM diagnosis code of hyponatremia (276.1).

Results

A total of 40,668 outpatient serum sodium laboratory results were identified as hyponatremic (serum sodium < 136 mmol/L). The sensitivity of ICD-9-CM codes for hyponatremia in outpatient professional claims within 15 days before or after the laboratory date was 3.5%. Even for severe cases (serum sodium ≤ 125 mmol/L), sensitivity was < 30%. Specificity was > 99% for all cutoff points.

Conclusion

ICD-9-CM codes in administrative data are insufficient to identify hyponatremia in an outpatient population.

Selecting an optimal prognostic system for liver cirrhosis: the model for end-stage liver disease and beyond

In comparison with the Child-Turcotte-Pugh (CTP) system, recent studies suggested that the model for end-stage liver disease (MELD) may more accurately predict the survival for patients with cirrhosis. In the US, the liver allocation system was changed in 2002 from a status-based algorithm utilizing CTP scores to one using continuous MELD severity scores as a reference system in prioritizing adult patients on the waiting list. Direct evidence that demonstrates the benefits of MELD is the fact that the mortality rates of transplant candidates on the waiting list have remarkably decreased after the implementation of the MELD. The MELD score is closely associated with the degree of portal hypertension as reflected by the hepatic venous pressure gradient. Hyponatraemia occurs as a result of advanced cirrhosis, and a serum sodium (Na) level <126 mEq/L at the time of listing for transplantation is a strong independent predictor of mortality. Several MELD-derived prognostic models that incorporate serum Na into calculation have been proposed in the hopes of further improving the MELD's prognostic accuracy. Additionally, serum parameters such as creatinine and international normalized ratio are subject to interlaboratory variations and may need unifying standartisations. Patients with refractory complications of cirrhosis may need a priority MELD score to prioritize them on the waiting list. Appropriate modifications and the fine-tuning of the MELD based on well-designed prospective studies are necessary in solving the current controversial issues.

Serum sodium and hydration status predict transplant-free survival independent of MELD score in patients with cirrhosis

BACKGROUND AND AIM

Serum sodium may have prognostic value in addition to the model for end-stage liver disease (MELD) score for prediction of early mortality in patients listed for liver transplant. In patients with cirrhosis, over-hydration is a common feature but its prognostic value has not been evaluated. This study examines the independent prognostic significance of MELD, serum sodium and hydration status on long-term survival in patients with cirrhosis.

METHODS

Serum sodium and hydration (total body water as a percentage of fat-free mass) were measured in 227 consecutive cirrhotic patients (146 male, 81 female; median age 49 years, range 19-73 years; median MELD score 13, range 6-36). Patients with hepatocellular carcinoma or listed for liver transplantation at the time of initial assessment were excluded. A competing risks Cox proportional hazards analysis was performed to evaluate the influence of MELD, sodium and hydration on risk of death or transplant.

RESULTS

Median follow-up was 52 (range 4-93) months. Serum sodium and hydration were each associated with reduction in time to death or transplant on univariate analysis (sodium: hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.87-0.94, P < 0.0001; hydration: HR 1.20, 95% CI 1.10-1.30, P < 0.0001). On multivariate analysis, MELD, serum sodium and hydration were independently predictive of death or transplant (MELD: HR 1.12, 95% CI 1.06-1.19, P < 0.0001; sodium: HR 0.93, 95% CI 0.87-0.99, P = 0.04; hydration: HR 1.17, 95% CI 1.02-1.33, P = 0.02).

CONCLUSIONS

In non-waitlisted patients with cirrhosis, serum sodium is predictive of transplant or death independent of MELD score.

The transient receptor potential vanilloid-responsive 1 and 4 cation channels: role in neuronal osmosensing and renal physiology

PURPOSE OF REVIEW

To provide an overview of recent developments in the field of systemic osmoregulation, with attention to the brain and kidney.

RECENT FINDINGS

A number of pivotal observations underscore the primary importance of transient receptor potential channels in systemic osmoregulation and their involvement constitutes the focus of this review. Recent data suggest that transient receptor potential vanilloid-responsive 4 is a central sensor or effector of systemic hypotonicity, whereas an unidentified variant of transient receptor potential vanilloid-responsive 1 potentially serves an analogous role in systemic hypertonicity.

SUMMARY

Members of the transient receptor potential vanilloid-responsive subfamily of transient receptor potential channels are likely to serve as central sensors of systemic anisotonicity.

Performance of the new MELD-Na score in predicting 3-month and 1-year mortality in Chinese patients with chronic hepatitis B

The new Model for End-Stage Liver Disease (MELD)-Na score has been validated in a population predominantly affected by chronic hepatitis C and alcoholic liver disease. We aimed to validate the score in Chinese patients with chronic hepatitis B-related complications admitted to the hospital from 1996 to 2003. MELD and the new MELD-Na scores (MELD-Na = MELD + 1.59 [135 - Na] with maximum and minimum Na of 135 and 120 mmol/L, respectively) on initial admissions were calculated. Cox proportional hazard model was used to assess factors associated with mortality. The area under the receiver operator characteristic curve (AUC) was used to compare the predictive abilities of MELD and MELD-Na scores for 3-month and 1-yr mortalities. Patients with hepatocellular carcinoma were excluded. A total of 2,073 patients with liver disease were admitted during the study period and 363 patients had chronic hepatitis B-related complications other than hepatocellular carcinoma. At a median follow-up of 106 weeks, 134 patients died and 14 received liver transplantation. Patients with MELD-Na scores 11-20, 21-30, and >30 had mortality increased by 2.0-fold, 4.7-fold, and 7.6-fold, respectively, compared to patients with scores < or =10. At 3 months and 1 yr, the AUC of the MELD-Na score (0.75 and 0.79, respectively) was superior to those of the MELD score (0.72 and 0.75, respectively) (P = 0.004) in predicting mortality. In conclusion, the new MELD-Na score is a valid model to predict mortality in patients with complications of chronic hepatitis B.

Transjugular intrahepatic portosystemic shunt for refractory ascites: a meta-analysis of individual patient data

BACKGROUND & AIMS

Several randomized controlled trials have compared a transjugular intrahepatic portosystemic shunt (TIPS) with large-volume paracentesis in cirrhotic patients with refractory ascites. Although all agree that TIPS reduces the recurrence rate of ascites, survival is controversial. The aim of this study was to compare the effects of TIPS and large-volume paracentesis in cirrhotic patients with refractory ascites by means of meta-analysis of individual patient data from 4 randomized controlled trials.

METHODS

The study population consisted of 305 patients: 149 allocated to TIPS and 156 to paracentesis. Cumulative probabilities of transplant-free survival and of hepatic encephalopathy (HE) were estimated by the Kaplan-Meier method and differences assessed by log-rank test. The total number of HE episodes per patient was also compared between TIPS and paracentesis.

RESULTS

Tense ascites recurred in 42% of patients allocated to TIPS and 89% allocated to paracentesis (P < .0001). Sixty-five patients in the TIPS group and 78 in the paracentesis group died. The actuarial probability of transplant-free survival was significantly better in the TIPS group (P = .035). Cox regression analysis performed in a subgroup of 235 patients (114 allocated to TIPS and 121 to paracentesis) showed that age, serum bilirubin level, plasma sodium level, and treatment allocation were independently associated with transplant-free survival. The average number of HE episodes was significantly higher in the TIPS group (1.13 +/- 1.93 vs 0.63 +/- 1.18; P = .006), although the cumulative probability of developing the first episode of HE was similar between the groups (P = .19).

CONCLUSIONS

The present meta-analysis of individual patient data provides further evidence to the previous meta-analyses of literature data showing that TIPS significantly improves transplant-free survival of cirrhotic patients with refractory ascites.

The impact of serum sodium concentration on mortality after liver transplantation: a cohort multicenter study

Modification of the current allocation system for donor livers in the United States to incorporate recipient serum sodium concentration ([Na]) has recently been proposed. However, the impact of this parameter on posttransplantation mortality has not been previously examined in a large risk-adjusted analysis. We assessed the effect of recipient [Na] on the survival of all adults with chronic liver disease who received a first single organ liver transplant in the UK and Ireland during the period March 1, 1994 to March 31, 2005 (n=5,152) at 3 years, during the first 90 days, and beyond the first 90 days, adjusting for a wide range of recipient, donor, and graft characteristics. Compared to those with normal [Na] (135-145 meq/L; n=3,066), severely hyponatremic recipients ([Na]<130 meq/L, n=541), had a higher risk-adjusted mortality at 3 years (hazard ratio [HR] 1.28; 95% confidence interval [CI], 1.04-1.59; P<0.02). The excess mortality was, however, confined to the first 90 days (HR 1.55; 95% CI, 1.18-2.04; P<0.002) with no significant difference thereafter. This was also true for hypernatremic recipients ([Na]>45 meq/L, n=81), who had an even greater risk-adjusted mortality compared to normonatremic recipients (overall: HR 1.85; 95% CI, 1.25-2.73; P<0.002; <or=90 days: HR 2.29; 95% CI, 1.42-3.70; P<0.001; >90 days: HR 1.12; 95% CI, 0.55-2.29; P=0.8), whereas mildly hyponatremic recipients ([Na] 130-134 meq/L, n=1,127) had similar risk-adjusted mortality to those with normal [Na] at the same time points. In conclusion, recipient [Na] is an independent predictor of death following liver transplantation. Attempts to correct the [Na] toward the normal reference range are an important aspect of pretransplantation management.

Hospital-acquired hyponatremia—why are hypotonic parenteral fluids still being used?

Hospital-acquired hyponatremia can be lethal. There have been multiple reports of death or permanent neurological impairment in both children and adults. The main factor contributing to the development of hospital-acquired hyponatremia is routine use of hypotonic fluids in patients in whom the excretion of free water, which is retained in response to excess arginine vasopressin (AVP), might be impaired. The practice of administering hypotonic parental fluids was established over 50 years ago, before recognition of the fact that there are numerous potential stimuli for AVP production in most hospitalized patients. Virtually all neurological morbidity resulting from hospital-acquired hyponatremia has been associated with administration of hypotonic fluids. Multiple prospective studies have shown that 0.9% NaCl is effective prophylaxis against hyponatremia. There is not a single report in the literature of neurological complications resulting from the use of 0.9% NaCl in non-neurosurgical patients. Patients at greatest risk of developing hyponatremic encephalopathy following hypotonic fluid administration are children, premenopausal females, postoperative patients, and those with brain injury or infection, pulmonary disease or hypoxemia. When hyponatremic encephalopathy develops, immediate administration of 3% NaCl is essential. In this Review, we discuss the question of why administering hypotonic fluids is unphysiologic and potentially dangerous, the settings in which isotonic fluids should be administered to prevent hyponatremia, and the appropriate treatment of hyponatremic encephalopathy.

New agents for managing hyponatremia in hospitalized patients

PURPOSE

An overview of hyponatremia is provided, including its pathophysiology, clinical manifestations, signs and symptoms, and treatment, particularly with arginine vasopressin (AVP)-receptor antagonists.

SUMMARY

Hyponatremia (generally defined as a serum sodium concentration of <135 meq/L) is one of the most common electrolyte disorders in hospitalized and clinic patients. It may be caused by a number of conditions, including infections, heart disease, surgery, malignancy, and medication use. Clinical signs and symptoms such as hallucinations, lethargy, weakness, bradycardia, respiratory depression, seizures, coma, and death have been reported. Conventional treatment consists of fluid restriction and administration of hypertonic saline and pharmacologic agents, such as demeclocycline, lithium carbonate, and urea. These treatment options are often of limited effectiveness or difficult for patients to tolerate. AVP promotes the reabsorption of water in the renal collecting ducts by activation of V(2) receptors, resulting in water retention and dilution of serum solutes. The AVP-receptor antagonists, conivaptan, lixivaptan, and tolvaptan, are being studied for the treatment of hyponatremia. Conivaptan has been shown in clinical trials to increase free-water excretion and safely normalize serum sodium concentrations in patients with hyponatremia and is well tolerated. Also in clinical trials, lixivaptan and tolvaptan have safely improved serum sodium concentrations in patients with hyponatremia.

CONCLUSION

Hyponatremia is a serious health condition for which treatment should be carefully performed. As new agents for treating hyponatremia, AVP-receptor antagonists have demonstrated efficacy and safety in clinical trials and may serve as significant improvements in the current treatment options for managing this disorder.

Hyponatremia, arginine vasopressin dysregulation, and vasopressin receptor antagonism

Hyponatremia is often associated with arginine vasopressin (AVP) dysregulation that is regulated by the hypothalamo-neurohypophyseal tract in response to changes in plasma osmolality, commonly in patients with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Potentially lethal complications of hyponatremia most frequently involve the central nervous system and include anorexia, fatigue, lethargy, delirium, seizures, hypothermia and coma, and require prompt treatment. Chronic hyponatremia also complicates patient care and is associated with increased morbidity and mortality, particularly among patients with congestive heart failure. Conventional treatments for hyponatremia (e.g. fluid restriction, diuretic treatment, and sodium replacement) may not be effective in all patients and can lead to significant adverse events. Preclinical and clinical trial results have shown that AVP receptor antagonism is a promising approach to the treatment of hyponatremia that directly addresses the effects of increased AVP and consequent decreased aquaresis, the electrolyte-sparing excretion of free water. Agents that antagonize V(2) receptors promote aquaresis and can lead to increased serum sodium. Dual-receptor antagonism, in which both V(2) and V(1A) receptors are blocked, may provide additional benefits in patients with hyponatremia.

Hyponatremia in cirrhosis: Results of a patient population survey

Low serum sodium concentration is an independent predictor of mortality in patients with cirrhosis, but its prevalence and clinical significance is unclear. To evaluate prospectively the prevalence of low serum sodium concentration and the association between serum sodium levels and severity of ascites and complications of cirrhosis, prospective data were collected on 997 consecutive patients from 28 centers in Europe, North and South America, and Asia for a period of 28 days. The prevalence of low serum sodium concentration as defined by a serum sodium concentration < or =135 mmol/L, < or =130 mmol/L, < or =125 mmol/L, and < or =120 mmol/L was 49.4%, 21.6%, 5.7%, and 1.2%, respectively. The prevalence of low serum sodium levels (<135 mmol/L) was high in both inpatients and outpatients (57% and 40%, respectively). The existence of serum sodium <135 mmol/L was associated with severe ascites, as indicated by high prevalence of refractory ascites, large fluid accumulation rate, frequent use of large-volume paracentesis, and impaired renal function, compared with normal serum sodium levels. Moreover, low serum sodium levels were also associated with greater frequency of hepatic encephalopathy, spontaneous bacterial peritonitis, and hepatorenal syndrome, but not gastrointestinal bleeding. Patients with serum sodium <130 mmol/L had the greatest frequency of these complications, but the frequency was also increased in patients with mild reduction in serum sodium levels (131-135 mmol/L). In conclusion, low serum sodium levels in cirrhosis are associated with severe ascites and high frequency of hepatic encephalopathy, spontaneous bacterial peritonitis, and hepatorenal syndrome.

Hyponatremia, fluid-electrolyte disorders, and the syndrome of inappropriate antidiuretic hormone secretion: diagnosis and treatment options

OBJECTIVE

To review the types and causes of hyponatremia and examine the various strategies for treatment of this disorder.

METHODS

A systematic review of the current literature is provided, targeting endocrinology clinicians who consult with hospital medical and surgical staff when managing patients with hyponatremia. Treatment for euvolemic and hypervolemic hyponatremia with arginine vasopressin receptor antagonists is presented, which provides a new treatment option for patients with disorders of water metabolism.

RESULTS

Hyponatremia is recognized as the most common electrolyte disorder encountered in the clinical setting and is associated with a variety of conditions including dilutional disorders, such as congestive heart failure and the syndrome of inappropriate antidiuretic hormone secretion, and depletional disorders, such as diarrhea and vomiting or blood loss. Most cases of mild hyponatremia can be treated effectively. Acute, severe hyponatremia that is untreated or treated ineffectively, however, can lead to serious neurologic outcomes or death. With the poor prognosis for morbidity and mortality in patients with severe hyponatremia, hospital-based clinicians must identify those at risk for hyponatremia and suggest appropriate treatment intervention. A new class of drugs, the arginine vasopressin receptor antagonists, targets receptors on collecting duct cells of the nephron and causes aquaresis, the excretion of free water. This therapy leads to the restoration of sodium-water homeostasis in patients with euvolemic and hypervolemic hyponatremia.

CONCLUSION

With many hospitalized patients at risk for hyponatremia, especially elderly patients in critical care and postsurgical units, identification of involved patients, recommendation of appropriate treatment, and awareness of new therapeutic options are critical.

Hyponatremia in cirrhosis: clinical features and management

The presence of dilutional hyponatremia has a poor prognosis for survival in patients with cirrhosis and ascites. Effective and safe treatments are needed to improve prognosis in patients with cirrhosis and dilutional hyponatremia. The initial approach to management includes fluid restriction, low sodium diet, and minimizing the use of diuretics. In addition, the use of hypertonic saline should be avoided in patients with cirrhosis and dilutional hyponatremia. Furthermore, patients should be placed on the top of the list for liver transplantation if they are appropriate candidates. Although V2 arginine vasopressin receptor antagonists that selectively enhance solute-free water excretion in patients with cirrhosis seem very promising, two points must be considered in relation to the available data. First, although the results of phase-2 studies are encouraging, the efficacy and safety of these compounds should be further evaluated. Second, the clinical utility of these agents in cirrhosis has only been assessed in short-term studies. The long-term effects of these drugs remain unknown. Future research with these compounds should not only focus on the effects on serum sodium, but also on treatment and prevention of recurrence of ascites. In addition, the possible beneficial effects of these drugs in the prevention of hepatic encephalopathy would be worth studying.

Mineral metabolism in dimethylnitrosamine-induced hepatic fibrosis

OBJECTIVES

Complications such as ascites during the pathogenesis of hepatic fibrosis and cirrhosis may lead to several abnormalities in mineral metabolism. In the present investigation, we have monitored serum and liver concentrations of calcium, magnesium, sodium and potassium during experimentally induced hepatic fibrosis in rats.

DESIGN AND METHODS

The liver injury was induced by intraperitoneal injections of dimethylnitrosamine (DMN; N-nitrosodimethylamine, NDMA) in doses 1 mg/100 g body weight on 3 consecutive days of each week over a period of 21 days. Calcium, magnesium, sodium and potassium were measured by atomic absorption spectrophotometry in the serum and liver on days 7, 14 and 21 after the start of DMN administration.

RESULTS

Negative correlations were observed between liver function tests and serum mineral levels, except with albumin. Calcium, magnesium, potassium and sodium concentrations in the serum were decreased after the induction of liver injury. The liver calcium content was increased after DMN treatment. No change occurred in liver sodium content. However, magnesium and potassium content was significantly reduced in the hepatic tissue.

CONCLUSIONS

The results suggest that DMN-induced hepatic fibrosis plays certain role in the alteration of essential elements. The low levels of albumin and the related ascites may be one of the major causes of the imbalance of mineral metabolism in hepatic fibrosis and further aggravation of the disease.

Liver transplantation organ allocation between Child and MELD

Liver transplantation (LT) has been established as the most effective therapy for acute and chronic liver diseases over the last few decades due to its excellent long-term results. At the beginning of the LT era, donor organs were allocated based on waiting time. However, as the number of LT candidates consistently increased, a specific allocation system became necessary to prioritize the large number of patients waiting for a limited pool of organs. The LT candidates were categorized into different urgency levels based on their hospital status, degree of liver disease as measured by the Child-Turcotte-Pugh score, and accompanying complications of liver disease, such as ascites, variceal bleeding or hepatocellular carcinoma. The majority of European countries, including Austria, still rely on this organ allocation system. In the United States, however, a new allocation system based on the risk of death without transplantation, assessed by the Model for End-stage Liver Disease (MELD), was initiated in February 2002. Recent reports have shown that the introduction of the MELD system led to a reduction in waiting list mortality, but also that the MELD score has several limitations that call for further refinements. In the transplant community there are reasonable doubts that MELD is actually superior to the Child-Turcotte Pugh score. Therefore, the optimal liver organ allocation system is yet to be defined.