Lack of evidence for a continuum between hepatorenal syndrome and acute tubular necrosis

Understanding and Treating Hepatorenal Syndrome: Insights from Recent Research

Acute kidney injury (AKI) is a critical and often fatal complication in decompensated cirrhosis, significantly affecting inpatient survival rates. Hepatorenal syndrome (HRS), a distinct subtype of AKI, develops in individuals with advanced cirrhosis and portal hypertension. It is marked by progressive kidney dysfunction, poor prognosis, and frequently causes death before liver transplantation. The pathogenesis of HRS involves vasodilation of the splanchnic vessels, leading to overactivation of the endogenous vasoactive systems, circulatory dysfunction, and reduced renal perfusion, which ultimately impairs glomerular filtration. Recent studies have highlighted the role of systemic inflammation in exacerbating renal damage. Despite these changes, renal histology in HRS usually shows no significant abnormalities, and there is typically no hematuria, proteinuria, or abnormal findings on ultrasound. Common risk factors for HRS include spontaneous bacterial peritonitis, infections, and large-volume paracentesis without albumin infusion. Diagnosing HRS is challenging, particularly in distinguishing it from acute tubular necrosis, due to the absence of specific biomarkers. Treatment primarily involves vasoconstrictors such as terlipressin and albumin, with liver transplantation being the definitive therapeutic option. This review provides an updated understanding of HRS, addressing its pathophysiology, diagnosis, management, and future challenges, based on recent expert consensus.

Renal damage in Hepatorenal Syndrome: A still unsolved issue

Acute kidney injury (AKI) is a common complication of cirrhosis, burdened by high morbidity and mortality rates and progression to chronic kidney disease. Hepatorenal syndrome (HRS) is a peculiar type of functional AKI observed in cirrhotic patients with ascites. HRS diagnosis is still clinical, once pre-renal azotemia and intrinsic kidney damage have been excluded by applying well-established and internationally adopted criteria. HRS is considered reversible because of the absence of intrinsic renal damage. However, HRS reversibility has been questioned, due to the lack of response to treatment with vasoconstrictors plus albumin in a relevant percentage of patients and to the persistence of renal dysfunction in HRS patients who underwent liver transplantation (LT). Indeed, LT is the only ultimate treatment, as it solves both liver failure and portal hypertension. Thus, the presence of renal damage in HRS can be hypothesized. In this scenario, neutrophil gelatinase-associated lipocalin (NGAL), one of the most promising biomarkers, may help in characterizing the type of renal injury, distinguishing between HRS and acute tubular necrosis. This review gathers the available evidence in favor and against the presence of structural lesions in HRS in terms of either renal histology and urinary biomarkers with a particular focus on NGAL. The ability to properly characterize which component of renal dysfunction prevails - functional rather than structural - entails a relevant clinical impact for the treatment of these patients, both in terms of medical therapy and liver vs. combined liver-kidney transplantation.

Evaluation of Longitudinal Exposure to Tacrolimus as a Risk Factor of Chronic Kidney Disease Occurrence Within the First-year Post-Liver Transplantation

BACKGROUND

Renal failure is predictive of mortality in the early postliver-transplantation period and calcineurin inhibitors toxicity is a main challenge. Our aim is to assess the impact of longitudinal tacrolimus exposure (TLE) and other variables on chronic kidney disease (CKD)-free 1-year-survival.

METHODS

Retrospective data of consecutive patients transplanted between 2011 and 2016 and treated with tacrolimus were collected. TLE and all relevant pre- and post-liver transplantation (LT) predictive factors of CKD were tested and included in a time-to-event model. CKD was defined by repeated estimated glomerular filtration rate (eGFR) values below 60 mL/min/1.73m2 at least for the last 3 months before M12 post-LT.

RESULTS

Data from 180 patients were analyzed. CKD-free survival was 74.5% and was not associated with TLE. Pre-LT acute kidney injury (AKI) and eGFR at 1-month post-LT (eGFRM1) <60 mL/min/1.73m2 were significant predictors of CKD. By distinguishing 2 situations within AKI (ie, with or without hepatorenal syndrome [HRS]), only HRS-AKI remained associated to CKD. HRS-AKI and eGFRM1 <60 mL/min/1.73m2 increased the risk of CKD (hazard ratio, 2.5; 95% confidence interval, 1.2-4.9; hazard ratio, 4.8; 95% confidence interval, 2.6-8.8, respectively).

CONCLUSIONS

In our study, TLE, unlike HRS-AKI and eGFRM1, was not predictive of CKD-free survival at 1-year post-LT. Our results once again question the reversibility of HRS-AKI.

End-stage liver disease: Management of hepatorenal syndrome

Hepatorenal syndrome (HRS) is a serious complication of cirrhosis with high morbidity and mortality rates. Recently, the definition of HRS type 1 has been updated and is now called HRS-AKI. This new definition reduces the risk of delaying HRS treatment and eliminates the need to establish a minimum creatinine cut-off for the diagnosis of HRS-AKI. From a pathophysiological point of view, newly identified mechanisms involved in the development of HRS are related to the inflammatory response, conditioning the development of extrahepatic organ dysfunction in patients with cirrhosis. One of the main challenges for the diagnosis of HRS is the validation of new biomarkers to obtain an early and differential diagnosis of kidney injury (eg HRS vs. ATN). Treatment of HRS is based on the use of vasoconstrictive agents in combination with albumin and terlipressin is the most widely used vasoconstrictor drug, with a high response rate. The effects of a continuous infusion of terlipressin at a dose of 2-12 mg/day was similar to bolus administration, but with lower rates of adverse events. Finally, MELD/MELD-Na which includes creatinine as one of its main determinants gives AKI-HRS patients priority on the waiting list (WL) for liver transplant (LT). However, the MELD and MELD-Na scores are reduced in responding patients, resulting a longer waiting time in these patients than in non-responders. Thus, the initial MELD/MELD-Na score (pre-treatment value) should be used to prioritize patients on the WL for LT in these cases.

Monitoring Renal Function and Therapy of Hepatorenal Syndrome Patients with Cirrhosis

Acute kidney injury (AKI) is a frequent complication in patients with cirrhosis. Patients with cirrhosis can develop AKI due to different causes. Hepatorenal syndrome (HRS) is a unique cause of AKI occurring in patients with advanced cirrhosis and is associated with high short-term mortality. The differential diagnosis between different causes of AKI may be challenging. In this regard, new urine biomarkers may be helpful. Liver transplantation is the definitive treatment of patients with HRS-AKI. Vasoconstrictors and albumin represent the first-line pharmacologic treatment of HRS-AKI. This review summarizes current knowledge for the diagnosis and management of HRS in cirrhosis.