Hyponatremia in Cirrhosis: Implications for Liver Transplantation

Hyponatremia in the Context of Liver Disease

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

Evidence-based hyponatremia management in liver disease

Hyponatremia is primarily a water balance disorder associated with high morbidity and mortality. The pathophysiological mechanisms behind hyponatremia are multifactorial, and diagnosing and treating this disorder remains challenging. In this review, the classification, pathogenesis, and step-by-step management approaches for hyponatremia in patients with liver disease are described based on recent evidence. We summarize the five sequential steps of the traditional diagnostic approach: 1) confirm true hypotonic hyponatremia, 2) assess the severity of hyponatremia symptoms, 3) measure urine osmolality, 4) classify hyponatremia based on the urine sodium concentration and extracellular fluid status, and 5) rule out any coexisting endocrine disorder and renal failure. Distinct treatment strategies for hyponatremia in liver disease should be applied according to the symptoms, duration, and etiology of disease. Symptomatic hyponatremia requires immediate correction with 3% saline. Asymptomatic chronic hyponatremia in liver disease is prevalent and treatment plans should be individualized based on diagnosis. Treatment options for correcting hyponatremia in advanced liver disease may include water restriction; hypokalemia correction; and administration of vasopressin antagonists, albumin, and 3% saline. Safety concerns for patients with liver disease include a higher risk of osmotic demyelination syndrome.

Intraoperative Renal Replacement Therapy in Orthotopic Liver Transplantation

Acute kidney injury in patients admitted to the hospital for liver transplantation is common, with up to 80% of pretransplant patients having some form of acute kidney injury. Many of these patients start on dialysis prior to their transplant and have it continued intraoperatively during their surgery. This review discusses the limited existing literature and expert opinion around the indications and outcomes around intraoperative dialysis (intraoperative renal replacement therapy) during liver transplantation. More specifically, we discuss which patients may benefit from intraoperative renal replacement therapy and the impact of hyponatremia and hyperammonemia on the dialysis prescription. Additionally, we discuss the complex interplay between anesthesia and intraoperative renal replacement therapy and how the need for clearance and ultrafiltration changes throughout the different phases of the transplant (preanhepatic, anhepatic, and postanhepatic). Lastly, this review will cover the limited data around patient outcomes following intraoperative renal replacement therapy during liver transplantation as well as the best evidence for when to stop dialysis.

Diagnosis and Management of Hyponatremia: A Review

IMPORTANCE

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

OBSERVATIONS

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

CONCLUSIONS AND RELEVANCE

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

Are MELD and MELDNa Still Reliable Tools to Predict Mortality on the Liver Transplant Waiting List?

Liver transplantation is the only curative treatment for end-stage liver disease. Unfortunately, the scarcity of donor organs and the increasing pool of potential recipients limit access to this life-saving procedure. Allocation should account for medical and ethical factors, ensuring equal access to transplantation regardless of recipient's gender, race, religion, or income. Based on their short-term prognosis prediction, model for end-stage liver disease (MELD) and MELD sodium (MELDNa) have been widely used to prioritize patients on the waiting list for liver transplantation resulting in a significant decrease in waiting list mortality/removal. Recent concern has been raised regarding the prognostic accuracy of MELD and MELDNa due, in part, to changes in recipients' profile such as body mass index, comorbidities, and general condition, including nutritional status and cause of liver disease, among others. This review aims to provide a comprehensive view of the current state of MELD and MELDNa advantages and limitations and promising alternatives. Finally, it will explore future options to increase the donor pool and improve donor-recipient matching.

Hyponatremia in Cirrhosis

Hyponatremia is the most common electrolyte disorder encountered in clinical practice, and it is a common complication of cirrhosis reflecting an increase in nonosmotic secretion of arginine vasopressin as a result of of the circulatory dysfunction that is characteristic of advanced liver disease. Hyponatremia in cirrhosis has been associated with poor clinical outcomes including increased risk of morbidity and mortality, poor quality of life, and heightened health care utilization. Despite this, the treatment of hyponatremia in cirrhosis remains challenging as conventional therapies such as fluid restriction are frequently ineffective. In this review, we discuss the epidemiology, clinical outcomes, pathogenesis, etiology, evaluation, and management of hyponatremia in cirrhosis.

Hyponatremia and Liver Transplantation: A Narrative Review

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

Perioperative Delta Sodium and Post-Liver Transplant Neurological Complications in Liver Transplant Recipients

BACKGROUND

Hyponatremia before liver transplant (LT) increases risk of post-LT neurological complications in patients with decompensated cirrhosis, but it is unknown to what extent change in sodium from pre- to post-LT influences risk of central nervous system (CNS) sequelae. We assessed the relationship between pre- to post-LT delta sodium and prevalence of CNS complications during LT hospitalization.

METHODS

We performed retrospective single-center chart review of 1265 adults with cirrhosis who underwent LT (2011-2020). Delta sodium is defined as the difference between maximum sodium within 48 h post-LT and lowest sodium within 7 d pre-LT. Primary outcomes are post-LT CNS events during same hospitalization-encephalopathy, delirium, seizure, coma, osmotic demyelination syndrome, or other altered mental status, determined by International Classification of Diseases codes. Secondary outcome is length of hospital stay post-LT (LOS). Logistic regression modeled association between delta sodium and post-LT CNS outcomes; negative binomial regression modeled LOS.

RESULTS

Median age was 59 y, 36% were female, and median MELD was 20. Median delta sodium was 8 mmol/L (interquartile range, 5-11). 194 (15%) experienced post-LT CNS complications. In multivariable analysis, controlling for confounders including pre-LT hyponatremia, every 5 mmol/L increase in delta sodium associated with 47% greater odds of CNS complication (95% confidence interval, 22%-77%). Delta sodium also associated with 7% increased LOS in adjusted regression (95% confidence interval, 3%-12%).

CONCLUSIONS

Adult LT recipients with higher perioperative delta sodium shifts displayed a higher risk of post-LT CNS complications, even after adjusting for pre-LT sodium. LT recipients, even those with pre-LT hyponatremia, may benefit from maintenance of stable serum sodium levels to minimize post-LT CNS complications.

Osmotic Demyelination Syndrome in Hospitalized Patients With Cirrhosis: Analysis of the National Inpatient Sample (NIS)

GOAL

Characterize prevalence of osmotic demyelination syndrome (ODS) in hospitalized patients with cirrhosis.

BACKGROUND

ODS is a serious complication of rapid serum sodium correction. Patients with cirrhosis experience labile sodium levels related to portal hypertension and diuretic use, often with rapid correction-intentional or unintentional-during hospitalizations.

STUDY

We used validated International Classification of Diseases, Ninth Revision (ICD-9) codes to identify inpatients 18 years and older with cirrhosis from the 2009-2013 National Inpatient Sample, excluding those with liver transplantation during hospitalization. The primary outcome was ODS (ICD-9 341.8). Baveno IV defined decompensated cirrhosis (stages 3 and 4); Charlson Comorbidity Index identified severe comorbid illness (score >3). Logistic regression modeled factors associated with ODS.

RESULTS

Of 547,544 adult inpatients with cirrhosis, 94 (0.02%) had ODS. Inpatients with versus without ODS were younger (54 vs. 57 y, P=0.0001), and more likely to have alcohol-related cirrhosis (58% vs. 33%, P<0.0001). ODS did not associate with decompensated cirrhosis (33% vs. 37%, P=0.43), specific complications (ascites 33% vs. 33%, P=0.97; hepatic encephalopathy 24% vs. 17%, P=0.06), or severe comorbid illness (12% vs. 16%, P=0.24). In both univariable and multivariable analysis, age [adjusted odds ratio (ORadj): 0.97, 95% confidence interval (CI): 0.95-0.99], female gender (ORadj: 1.53, 95% CI: 1.01-2.30), Hispanic race (ORadj: 0.41, 95% CI: 0.19-0.89), alcohol-related cirrhosis (ORadj: 2.65, 95% CI: 1.71-4.09), and congestive heart failure (ORadj: 0.37, 95% CI: 0.15-0.95) significantly associated with ODS.

CONCLUSION

In hospitalized patients with cirrhosis, ODS is extremely rare, and associated with alcohol-related cirrhosis, younger age, and female gender. ODS is not associated with liver disease severity, specific complications including ascites, or comorbid disease.

Clinical Implications, Evaluation, and Management of Hyponatremia in Cirrhosis

Hyponatremia is the most common electrolyte abnormality in patients with decompensated cirrhosis on Liver Transplantation (LT) waiting list. Most of these patients have dilutional or hypervolemic hyponatremia secondary to splanchnic vasodilatation. Excessive secretion of the antidiuretic hormone also plays an important role. Hypervolemic hyponatremia is commonly associated with refractory ascites, spontaneous bacterial peritonitis, and hepatic encephalopathy. Although uncommon, the use of diuretics and laxatives can cause hypovolemic hyponatremia that is characterized by the striking absence of ascites or pedal edema. Clinical features are often nonspecific and depend on the acuity of onset rather than the absolute value of serum sodium. Symptoms may be subtle, including nausea, lethargy, weakness, or anorexia. However, rarely patients may present with confusion, seizures, psychosis, or coma. Treatment includes discontinuation of diuretics, beta-blockers, and albumin infusion. Hypertonic saline (3%) infusion may be used in patients with very low serum sodium (<110 mmol/L) or when patients present with seizures or coma. Short-term use of Vasopressin (V₂) receptor antagonists may also be used to normalize sodium levels prior to LT. However, all these measures may be futile, and LT remains the definite treatment in these patients to improve survival. In this review, we describe the classification, pathogenesis of hyponatremia, and its clinical implications in patients with cirrhosis. Approach to these patients along with management will also be discussed briefly.

Extreme hyponatremia as a risk factor for early mortality after liver transplantation in the MELD-sodium era

The impact of hyponatremia on waitlist and post-transplant outcomes following the implementation of MELD-Na-based liver allocation remains unclear. We investigated waitlist and postliver transplant (LT) outcomes in patients with hyponatremia before and after implementing MELD-Na-based allocation. Adult patients registered for a primary LT between 2009 and 2021 were identified in the OPTN/UNOS database. Two eras were defined; pre-MELD-Na and post-MELD-Na. Extreme hyponatremia was defined as a serum sodium concentration ≤120 mEq/l. Ninety-day waitlist outcomes and post-LT survival were compared using Fine-Gray proportional hazard and mixed-effects Cox proportional hazard models. A total of 118 487 patients were eligible (n = 64 940: pre-MELD-Na; n = 53 547: post-MELD-Na). In the pre-MELD-Na era, extreme hyponatremia at listing was associated with an increased risk of 90-day waitlist mortality ([ref: 135-145] HR: 3.80; 95% CI: 2.97-4.87; P < 0.001) and higher transplant probability (HR: 1.67; 95% CI: 1.38-2.01; P < 0.001). In the post-MELD-Na era, patients with extreme hyponatremia had a proportionally lower relative risk of waitlist mortality (HR: 2.27; 95% CI 1.60-3.23; P < 0.001) and proportionally higher transplant probability (HR: 2.12; 95% CI 1.76-2.55; P < 0.001) as patients with normal serum sodium levels (135-145). Extreme hyponatremia was associated with a higher risk of 90, 180, and 365-day post-LT survival compared to patients with normal serum sodium levels. With the introduction of MELD-Na-based allocation, waitlist outcomes have improved in patients with extreme hyponatremia but they continue to have worse short-term post-LT survival.

Perioperative Evolution of Sodium Levels in Cirrhotic Patients Undergoing Liver Transplantation: An Observational Cohort and Literature Review

Background & Aims

Hyponatremia is an important predictor of early death among cirrhotic patients in the orthotopic liver transplantation (OLT) waiting list. Evidence exists that prioritizing OLT waiting list according to the MELD score combined with plasma sodium concentration might prevent pre transplantation death. However, the evolution of plasma sodium concentrations during the perioperative period of OLT is not well known. We aimed to describe the evolution of perioperative sodium concentration during OLT and its relation to perioperative neurohormonal responses.

Methods

Twenty-seven consecutive cirrhotic patients who underwent OLT were prospectively included in the study over a period of 27 months. We studied the evolution of plasma sodium levels, the hemodynamics, the neurohormonal response and other biological markers during the perioperative period of OLT.

Results

Among study's population, four patients had hyponatremia before OLT, all with Child cirrhosis. In patients with hyponatremia, plasmatic sodium reached normal levels during surgery, and sodium levels remained within normal ranges 1 day, 7 days, as well as 6 months after surgery for all patients. Creatinine clearance was decreased significantly during the perioperative period, while creatinine and cystatin C levels increased significantly. Neutrophil gelatinase-associated lipocalin (NGAL) and vasopressin levels did not change significantly in this period. Plasma renin activity, concentrations of norepinephrine and brain natriuretic peptide varied significantly during the perioperative period.

Conclusion

In our study, plasmatic sodium concentrations among hyponatremic cirrhotic patients undergoing OLT seem to reach normal levels after OLT and remain stable six months after surgery providing more evidence for the importance of sodium levels in prioritization of liver transplant candidates. Further investigation of rapid correction and stabilization of sodium levels after OLT, as observed in our study, would be of interest in order to fully understand the mechanisms involved in cirrhosis-related hyponatremia, its prognostic value and clinical implications.

Natremia and liver transplantation: The right amount of salt for a good recipe

An adequate balance between electrolytes and clear water is of paramount importance to maintaining physiologic homeostasis. Natremia imbalance and, in particular, hyponatremia is the most frequent electrolyte abnormality observed in hospitalized subjects, involving approximately one-fourth of them. Pathological changes occurring during liver cirrhosis predispose patients to an increased risk of sodium imbalance, and hypervolemic hyponatremia has been reported in nearly 50% of subjects with severe liver disease and ascites. Splanchnic vasodilatation, portal-systemic collaterals’ opening and increased excretion of vasoactive modulators are all factors impairing clear water handling during liver cirrhosis. Of concern, sodium imbalance has been consistently reported to be associated with increased risk of complications and reduced survival in liver disease patients. In the last decades clinical interest in sodium levels has been also extended in the field of liver transplantation. Evidence that [Na⁺] in blood is an independent risk factor for in-list mortality led to the incorporation of sodium value in prognostic scores employed for transplant priority, such as model for end-stage liver disease-Na and UKELD. On the other hand, severe hyponatremic cirrhotic patients are frequently delisted by transplant centers due to the elevated risk of mortality after grafting. In this review, we describe in detail the relationship between sodium imbalance and liver cirrhosis, focusing on its impact on peritransplant phases. The possible therapeutic approaches, in order to improve transplant outcome, are also discussed. 

Hyponatremia in Cirrhosis: An Update

Hyponatremia is frequently seen in patients with ascites secondary to advanced cirrhosis and portal hypertension. Although not apparent in the early stages of cirrhosis, the progression of cirrhosis and portal hypertension leads to splanchnic vasodilation, and this leads to the activation of compensatory mechanisms such as renin-angiotensin-aldosterone system (RAAS), sympathetic nervous system, and antidiuretic hormone (ADH) to ameliorate low circulatory volume. The net effect is the avid retention of sodium and water to compensate for the low effective circulatory volume, resulting in the development of ascites. These compensatory mechanisms lead to impairment of the kidneys to eliminate solute-free water in decompensated cirrhosis. Nonosmotic secretion of antidiuretic hormone (ADH), also known as arginine vasopressin, further worsens excess water retention and thereby hyponatremia. The management of hyponatremia in this setting is a challenge as conventional therapies for hyponatremia including fluid restriction and correction of hypokalemia are frequently inefficacious. In this review, we discuss the pathophysiology, complications, and various treatment modalities, including albumin infusion, selective vasopressin receptor antagonists, or hypertonic saline for patients with severe hyponatremia and those awaiting liver transplantation.

Predictors of hyponatremia following elective primary unilateral knee arthroplasty at a tertiary centre: A retrospective observational cohort and predictive model

Introduction

Hyponatremia is a common electrolyte disorder. This can be associated with nausea, disorientation and in more serious cases a decreased level of consciousness or neurological deficits. These symptoms may lead to increases in the cost of hospital care and significant morbidity. The purpose of this retrospective, observational cohort study is to investigate the impact of hyponatremia on patient and systems specific outcome measures in those undergoing elective, unilateral total knee arthroplasty (TKA) at two hospitals in Auckland, New Zealand over a twelve-month period.

Materials and methods

Patients were stratified into two groups based on the presence or absence of post-operative hyponatremia (defined as a blood sodium of <135 mmol/L with a concurrent decrease of ≥5 mmol/L between the pre- and post-operative recordings). Outcomes collected included Quality of Recovery - 15 (QOR) scores, time to assisted mobilisation, discharge ICD-10 complication codes and hospital length of stay.

Results

During the study period 236 patients underwent surgery. Eighty-six (36.4%) patients met criteria for post-operative hyponatremia. This finding was associated with prolongation of the hospital length of stay (4.17 (3.26-5.18) versus 4.28 (3.31-5.45) days, p = 0.031) and a reduction in the QOR score on the second post-operative day (113.0 (99.5-126.5) versus 105.0 (94.0-118.0), p = 0.039). There was no difference in the time to assisted mobilisation.

Conclusions

Hyponatremia is a common finding following TKA. This abnormality is associated with small changes in patient specific outcome measures. These implications of these findings may become more significant in settings where same day or rapid discharge from hospital is targeted.

A 'real-world' analysis of risk factors for post liver transplant delirium and the effect on length of stay

BACKGROUND

The development of delirium has been previously demonstrated to be associated with an increased risk of mortality and length of stay post liver transplant (LTx) with multiple risk factors being identified in previous studies. In this study, we have aimed to identify the most important variables associated with the onset of post-LTx delirium and understand the effect on length of stay (LOS).

METHODS

All liver transplants for chronic liver disease between 1 August 2012 and 1 August 2017 were included (n = 793). Data were collected for analysis retrospectively from electronic patient records.

RESULTS

Delirium is associated with an overall increased hospital and ICU LOS but not one-year mortality. The risk of developing post-LTx delirium was the greatest among patients: with post-LTx sepsis, who required renal sparing immunosuppression, who received donation after cardiac death (DCD) grafts and who were older. Patients with autoimmune hepatitis, primary biliary cholangitis or primary sclerosing cholangitis seemed to be at lower risk of post-LTx delirium. However, global patient LOS was only prolonged in patients with sepsis and renal failure.

CONCLUSION

Many of the risk factors previously described to be associated with the development of post-LTx delirium were not demonstrated to be significant in this study. Sepsis, renal failure, older age and DCD use are associated with delirium post-LTx. It is unclear if this syndrome is an independent risk factor for increased LOS or if it is a symptom of well established syndromes associated with increased LOS. The role for prophylactic strategies to reduce the incidence of post-LTx delirium is therefore unclear.

Hypervolemic hyponatremia and transplant-free survival in children with cirrhosis due to biliary atresia

BACKGROUND

Biliary atresia is the number one cause of cirrhosis and liver transplantation in children. Hyponatremia is the most important electrolytic disturbance observed in decompensated cirrhosis. Studies of hyponatremia in cirrhotic children are scarce and those that exist have defined hyponatremia as serum sodium < 130 mEq/L lasting for at least 7 days.

METHODS

We evaluated transplant-free survival (Kaplan-Meier) of children with cirrhosis due to biliary atresia and serum sodium < 130 mEq/L persisting for 1, 2-6, and ≥7 days. This was a single-center, historical cohort that included all patients aged ≤ 18 years on a liver transplantation waiting list.

RESULTS

We studied 128 patients. The overall frequency of hyponatremia was 30.5% (39/128). Thirteen patients (10.2%) had hyponatremia when put on the list, and 20.3% developed it during follow-up. The Kaplan-Meier overall transplant-free survival rate was 83.3%. Patients with persistent hyponatremia for at least two days had the lowest transplant-free survival. Glomerular filtration rate (P = .00, RR = 0.96, IC 95% = 0.94-0.99), BMI/age Z-score (P = .02, RR = 0.59, IC 95% = 0.39-0.91), INR (P = .00, RR = 1.43, IC 95% = 1.17-1.74), and serum sodium (P = .04, RR = 0.91, IC 95% = 0.84-0.99) were independently associated with transplant-free survival. We did not observe any difference in mortality prediction after adding sodium to the original PELD score.

CONCLUSIONS

We conclude that persistent hyponatremia lasting at least two days may herald poor prognosis for children with cirrhosis due to biliary atresia.