Reconsidering a "chopped liver": the need for improving glomular filtration rate estimation for hepatic transplantation

Hepatorenal Syndrome Type 1: Diagnosis and Treatment

Hepatorenal syndrome (HRS) is a feared complication in patients with advanced cirrhosis and is associated with significant morbidity and mortality. While recognized as a distinct physiologic condition for well over one hundred years, a lack of objective diagnostic tests has made the diagnosis one of exclusion. Since 1979, multiple sets of diagnostic criteria have been proposed. Though varying in detail, the principal intent of these criteria is to identify patients with severe, functional acute kidney injury that is unresponsive to volume resuscitation and exclude those with structural injury. However, accurate differential diagnosis remains challenging. Recently, multiple urinary biomarkers of kidney injury, including neutrophil gelatinase-associated lipocalin, have been studied as a means of objectively phenotyping etiologies of acute kidney injury in patients with cirrhosis. Along with markers reflecting tubular functional integrity, including the fractional excretion of sodium, injury markers will likely be incorporated into future diagnostic criteria. Making an accurate diagnosis is critical, as therapeutic options exist for HRS but must be given in a timely manner and only to those patients likely to benefit. Terlipressin, an analog of vasopressin, is the first line of therapy for HRS in much of the world and has recently been approved for use in the United States. Significant questions remain regarding the optimal dosing strategy, metrics for titration, and the potential role of point-of-care ultrasound to help guide concurrent albumin administration.

North American Practice-Based Recommendations for Transjugular Intrahepatic Portosystemic Shunts in Portal Hypertension

Complications of portal hypertension, including ascites, gastrointestinal bleeding, hepatic hydrothorax, and hepatic encephalopathy, are associated with significant morbidity and mortality. Despite few high-quality randomized controlled trials to guide therapeutic decisions, transjugular intrahepatic portosystemic shunt (TIPS) creation has emerged as a crucial therapeutic option to treat complications of portal hypertension. In North America, the decision to perform TIPS involves gastroenterologists, hepatologists, and interventional radiologists, but TIPS creation is performed by interventional radiologists. This is in contrast to other parts of the world where TIPS creation is performed primarily by hepatologists. Thus, the successful use of TIPS in North America is dependent on a multidisciplinary approach and technical expertise, so as to optimize outcomes. Recently, new procedural techniques, TIPS stent technology, and indications for TIPS have emerged. As a result, practices and outcomes vary greatly across institutions and significant knowledge gaps exist. In this consensus statement, the Advancing Liver Therapeutic Approaches group critically reviews the application of TIPS in the management of portal hypertension. Advancing Liver Therapeutic Approaches convened a multidisciplinary group of North American experts from hepatology, interventional radiology, transplant surgery, nephrology, cardiology, pulmonology, and hematology to critically review existing literature and develop practice-based recommendations for the use of TIPS in patients with any cause of portal hypertension in terms of candidate selection, procedural best practices and, post-TIPS management; and to develop areas of consensus for TIPS indications and the prevention of complications. Finally, future research directions are identified related to TIPS for the management of portal hypertension.

Serum cystatin C unmasks renal dysfunction in cirrhosis and performs better in estimation of glomerular filtration rate

In this study, we aimed to measure glomerular filtration rate (mGFR) using ⁹⁹Tc DTPA in patients with Child-Pugh C cirrhosis and normal serum creatinine levels; and to compare the performance of creatinine and cystatin C-based equations [estimated GFRs (eGFRs)] to ⁹⁹TcDTPA GFR in the same group. We selected a group of 65 consecutive patients with advanced liver cirrhosis and apparently normal renal function by serum creatinine alone. Patients with confounding and reversible factors were excluded. Demographic data, blood, urine, and imaging tests along with simultaneous measurement of serum creatinine and cystatin C were analyzed. The GFR was measured by ⁹⁹Tc DTPAscintigraphy (mGFR) in 41 patients. We compared the performance of chronic kidney disease epidemiology collaboration (CKD-EPI-creatinine, CKD-EPI-cystatinC, CKD-EPI-creatinine-cystatinC) and Modification of Diet in Renal Disease equation equations for bias (mean difference), precision (root mean square error), and accuracy (P10 and P30). Bland-Altman plots were used to show the agreement of eGFR and mGFR. Twenty-five out of 41 patients (61%) had significant renal dysfunction (GFR ≤60 mL/min/ 1.73m²) by ⁹⁹TcDTPA in our study and three patients were already in Stage 4 CKD. Unlike serum creatinine, serum cystatin C values were deranged in these patients. Among all GFR estimating formulae, CKD-EPI-creatinine-cystatinC combined equation had the least bias (-2.3), superior precision (7.1), highest P30 accuracy (78%), good sensitivity (87.5%), and best specificity (96%) in our study. Two-thirds of patients with cirrhosis had significant renal impairment despite having normal serum creatinine. Isolated serum creatinine values are misleading in cirrhosis. Cystatin C unmasks renal dysfunction in these patients. CKD-EPI-creatinine-cystatinC equation showed the best correlation and accuracy with ⁹⁹TcDTPA GFR in our study. Creatinine based GFR estimation is fallacious in cirrhosis. Cystatin C and equations based on it may be worthwhile in liver disease.

A Model for Glomerular Filtration Rate Assessment in Liver Disease (GRAIL) in the Presence of Renal Dysfunction

Estimation of glomerular filtration rate (eGFR) in patients with liver disease is suboptimal in the presence of renal dysfunction. We developed a model for GFR assessment in liver disease (GRAIL) before and after liver transplantation (LT). GRAIL was derived using objective variables (creatinine, blood urea nitrogen, age, gender, race, and albumin) to estimate GFR based on timing of measurement relative to LT and degree of renal dysfunction (www.bswh.md/grail). The measured GFR (mGFR) by iothalamate clearance (n = 12,122, 1985-2015) at protocol time points before/after LT was used as reference. GRAIL was compared with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD-4, MDRD-6) equations for mGFR < 30 mL/min/1.73 m² . Prediction of development of chronic kidney disease (mGFR < 20 mL/min/1.73 m² , initiation of chronic dialysis) and listing or receipt of kidney transplantation within 5 years was examined in internal cohort (n = 785) and external validation (n = 68,217, 2001-2015). GRAIL had less bias and was more accurate and precise as compared with CKD-EPI, MDRD-4, and MDRD-6 at time points before/after LT for low GFR. For mGFR < 30 mL/min/1.73 m² , the median difference (eGFR-mGFR) was GRAIL: 5.24 (9.65) mL/min/1.73 m² as compared with CKD-EPI: 8.70 (18.24) mL/min/1.73 m² , MDRD-4: 8.82 (17.38) mL/min/1.73 m² , and MDRD-6: 6.53 (14.42) mL/min/1.73 m² . Before LT, GRAIL correctly classified 75% as having mGFR < 30 mL/min/1.73 m² versus 36.1% (CKD-EPI), 36.1% (MDRD-4), and 52.8% (MDRD-6) (P < 0.01). An eGFR < 30 mL/min/1.73 m² by GRAIL predicted development of CKD (26.9% versus 4.6% CKD-EPI, 5.9% MDRD-4, and 10.5% MDRD-6) in center data and needing kidney after LT (48.3% versus 22.0% CKD-EPI versus 23.1% MDRD-4 versus 48.3% MDRD-6, P < 0.01) in national data within 5 years after LT. Conclusion: GRAIL may serve as an alternative model to estimate GFR among patients with liver disease before and after LT at low GFR.

Chronic kidney disease in liver transplantation: Evaluation of kidney function

Chronic kidney disease is one of the main comorbidities affecting liver transplant recipients. Most of those patients have some degree of acute or chronic kidney dysfunction at the time of transplantation, moreover they can also develop de novo chronic kidney disease once transplanted. An important increase in the incidence of chronic kidney disease in the «MELD era» has been observed. This phenomenon has partially been attributed to the weight that kidney function carries for organ allocation. In addition, the generalized use of calcineurin inhibitors has also been a contributing factor. It is of the utmost importance for us to be familiar with the current methods for evaluating kidney function before and after a liver transplantation. The two main biomarkers available today for that purpose are serum creatinine and cystatin C. Several equations have been derived from those biomarkers and have been tested in that context with mixed results, due to their biologic variability and the lack of standardization in their measurement. The gold standard continues to be the direct determination of the glomerular filtration rate through different methods; however, that is only done for research purposes. It is also essential to know the current classification of acute kidney injury and chronic kidney disease in order to make early diagnosis. The present review focuses on the recognition, diagnosis, and classification of chronic kidney disease and acute kidney injury in liver transplantation recipients.

Translational medical research and liver transplantation: systematic review

Translational medicine has become a priority, but there is still a big difference between the arrival of new treatments and investment. Basic science should not be neglected because the translation from basic research is not sustained in the absence of basic research. The purpose of this literature review was to analyze the translational medicine in the liver transplant field: liver ischemia-reperfusion injury (IRI), immunosuppression, clinical and surgical complications, small-for-size syndrome (SFSS), rejection, and ongoing innovations (liver machine, liver preservation, artificial livers, and regenerative medicine). We performed a systematic literature review that were updated in October 2016. The searches were performed in the Cochrane Central Register of Controlled Trials and Review, PubMed/Medline, Embase, and LILACS databases. All the selected studies on the management of translational medical research in liver transplantation (LT) were analyzed. Initially the search found 773 articles. Methodological viewing and analysis of the articles, followed by the application of scientific models, including translational medicine in the liver transplant field. In conclusions, this review demonstrates the application of scientific research with translation medical benefits regarding the LT. The literature has a great tendency, improvements and investments in the study of translational medicine in LT. Innovative studies and technologies from basic science help to clarify clinical doubts. Moreover, evidence increases the importance of scientific research in quality of clinical practice care.

Benefit of cystatin C in evaluation of renal function and prediction of survival in patients with cirrhosis

AIM

The assessment of renal function is of vital importance in management of patients with cirrhosis. While serum creatinine (Cr) is routinely used for this purpose, Cr-based estimated glomerular filtration rate (eGFR) does not reflect true renal function because of muscle wasting and impaired liver function. By contrast, cystatin C (CysC) is unrelated to muscle volume and liver function. In this study, we examined whether CysC-based GFR estimation is beneficial in assessment of renal function in patients with cirrhosis.

METHODS

First, we assessed the performance of GFR-predicting equations based on serum Cr or CysC in 14 patients with cirrhosis, by comparison with inulin clearance as a gold standard of GFR (measured GFR [mGFR]). Next, in 49 patients with cirrhosis, we examined serum Cr and CysC at baseline, and examined which GFR-predicting equations were more suitable for predicting the outcome.

RESULTS

In the first experiment, mGFR was 54.3 ± 23.0 mL/min, and CysC-based GFR-estimating equations had better performances compared with Cr-based equations in terms of bias, precision and accuracy. Cr-based estimated GFR (eGFRcreat) was significantly different from mGFR (P < 0.05). In the follow-up study of 49 patients (observational period, 30.7 ± 32.0 months), multivariate analysis demonstrated that CysC-based estimated GFR (eGFRcys), along with albumin, Child-Pugh grade and presence of hepatocellular carcinoma, was independently associated with overall survival (odds ratio, 4.19; 95% confidence interval, 1.44-12.2, P = 0.009).

CONCLUSION

These results suggest that eGFRcys could estimate renal function and predict outcome more accurately compared with Cr-based eGFR in cirrhotic patients.

Renal dysfunction in cirrhosis

PURPOSE OF REVIEW

Renal dysfunction causes significant morbidity in cirrhotic patients. Diagnosis is challenging because it is based on serum creatinine, which is used to calculate estimated glomerular filtration rate, which itself is not an ideal measure of renal function in patients with cirrhosis. Finding the exact cause of renal injury in patients with cirrhosis remains problematic due to the limitations of the current diagnostic tests. The purpose of this review is to highlight studies used to diagnose renal dysfunction in patients with renal dysfunction and review current treatments.

RECENT FINDINGS

New diagnostic criteria and classification of renal dysfunction, especially for acute kidney injury (AKI), have been proposed in hopes of optimizing treatment and improving outcomes. New biomarkers that help to differentiate structural from functional AKI in cirrhotic patients have been developed, but require further investigation. Vasoconstrictors are the most commonly recommended treatment of hepatorenal syndrome (HRS). Given the high mortality in patients with type 1 HRS, all patients with HRS should be evaluated for liver transplantation. When renal dysfunction is considered irreversible, combined liver-kidney transplantation is advised.

SUMMARY

Development of new biomarkers to differentiate the different types of AKI in cirrhosis holds promise. Early intervention in cirrhotic patients with renal dysfunction offers the best hope of improving outcomes.