Comparison of creatinine and cystatin formulae with 51 Chromium-ethylenediaminetetraacetic acid glomerular filtration rate in patients with decompensated cirrhosis

Prospective evaluation of cystatin C in the assessment of kidney dysfunction and survival in liver transplant candidates

Kidney dysfunction is associated with decreased survival in liver transplant (LT) candidates, yet serum creatinine (sCr) is a poor surrogate for glomerular filtration rate (GFR) in this population. Serum cystatin C (CysC) may provide a more accurate assessment of kidney function and predict outcomes. We performed a multicenter prospective cohort study of consecutive candidates for LT. CysC was obtained at LT evaluation (n = 244), and a subset underwent simultaneous I 125 -iothalamate clearance for measured GFR (mGFR) assessment (n = 137). Patients were followed to assess the need for pre-LT renal replacement therapy, simultaneous liver and kidney transplant, and survival. Estimated GFR (eGFR) based on MDRD-4, GRAIL, Royal Free Hospital Cirrhosis GFR, and the CKD-EPI equations was assessed for bias, precision, and accuracy in reference to mGFR. Receiver operator characteristic (AUROC) and competing risk survival analyses were performed. CysC more accurately discriminated mGFR than sCr at thresholds of ≤60 and ≤30 mL/min/1.73 m 2 with AUROC 0.92 ( p = 0.005) and 0.96 ( p =0.01), respectively. All eGFR equations overestimated GFR, especially among females ( p < 0.05). The GRAIL equation demonstrated the least bias, while CKD-EPI-cystatin C was associated with the greatest precision and lowest frequency of GFR overestimation. Among 165 recipients of LT, CysC discriminated pre-LT renal replacement therapy and the need for simultaneous liver and kidney transplant with AUROC of 0.70 and 0.85, respectively. Cumulative incidence of death, accounting for LT as a competing event, increased with CysC ( p = 0.002) but was not observed with sCr overall or among subgroups ( p = NS). CysC more accurately predicts thresholds of mGFR than sCr in candidates for LT. Elevated CysC discriminates pre-LT renal replacement therapy and simultaneous liver and kidney transplant and is strongly associated with survival in contrast with sCr. CysC is a promising tool to improve prognostication among candidates for LT.

Analysis of chronic kidney disease epidemiology in Kazakhstan using nationwide data for 2014-2020 and forecasting future trends of prevalence and mortality for 2030

According to the Global Burden of Disease (GBD) study, chronic kidney disease (CKD) was prevalent in 697.5 million individuals worldwide in 2017. By 2040, it is anticipated that CKD will rank as the fifth most common cause of death. This study aims to examine the epidemiology of CKD in Kazakhstan and to project future trends in CKD prevalence and mortality by 2030. The retrospective analysis was performed on a database acquired from the Unified National Electronic Health System for 703,122 patients with CKD between 2014 and 2020. During the observation period, 444,404 women and 258,718 men were registered with CKD, 459,900 (66%) were Kazakhs and 47% were older than 50. The incidence rate notably decreased: 6365 people per million population (PMP) in 2014 and 4040 people PMP in 2020. The prevalence changed from 10,346 to 38,287 people PMP, and the mortality rate increased dramatically from 279 PMP to 916 PMP. Kazakhstan's central regions, Turkestan and Kyzylorda were identified as the most burdensome ones. The ARIMA model projected 1,504,694 expected prevalent cases in 2030. The predicted mortality climbed from 17,068 cases in 2020 to 37,305 deaths in 2030. By 2030, the prevalence and mortality of CKD will significantly increase, according to the predicted model. A thorough action plan with effective risk factor management, enhanced screening among risk populations, and prompt treatment are required to lessen the burden of disease in Kazakhstan.

Quercetin flavonoid and vitamin C recuperate kidney functions in potassium bromate-induced renal dysfunction in Wistar rats

Studies into the functions and mechanisms of action of quercetin may be able to help dispel the negative effects of toxicants on renal toxicity due to its anti-inflammatory potential, as well as provide a simple, low-cost alternative for treating renal toxicity in developing nations. Therefore, the present study evaluated the ameliorative and renal protective activities of quercetin dihydrate in potassium bromate-induced, renal-toxic Wistar rats. Forty-five (45) mature female Wistar rats (180-200 g) were randomly grouped into nine (9) (n = 5). Group A served as general control. Nephrotoxicity was induced in groups B to I with the administration of potassium bromate. While group B served as a negative control, groups C-E received graded doses of quercetin (40, 60, and 80 mg/kg, respectively). Group F received 2.5 mg/kg/day of vitamin C, while groups G-I received vitamin C (2.5 mg/kg/day) and co-administration of a graded dose of quercetin (40, 60, and 80 mg/kg, respectively). Daily urine levels and final blood samples by retro-orbital techniques were collected for GFR, urea, and creatinine level assessment. The collected data were subjected to ANOVA and Tukey's post hoc test, and the results were presented as mean SEM with a p < 0.05 level considered significant. Body and organ weight and GFR were significantly reduced (p < 0.05), while serum and urine creatinine and urea were decreased in renotoxic animals. However, treatment with QCT reversed the renotoxic effects. We, therefore, concluded that quercetin administered alone or with vitamin C conferred renal protection by reversing KBrO3-induced renal toxicity in rats. Further studies to corroborate the present findings are recommended.

Update on Assessment of Estimated Glomerular Filtration Rate in Patients With Cirrhosis

Kidney disease is associated with adverse outcomes in patients with cirrhosis including increased post-liver transplantation (LT) mortality. Therefore, diagnosis and staging of kidney disease are critical to timely implementation of treatment and have important implications for transplant eligibility. Serum creatinine (sCr) is a key component of the Model for End-Stage Liver Disease score in LT candidates, and sCr-based estimated glomerular filtration rate (eGFR) values play an important role in determining medical urgency for LT. However, the use of sCr to assess kidney function may be limited in the cirrhotic milieu due to decreased creatinine production, interference of bilirubin with some laboratory assays for sCr, and expansion of the volume of distribution of creatinine. Therefore, conventional eGFR equations perform poorly in patients with cirrhosis and may overestimate kidney function leading to delayed diagnosis of acute kidney injury or lower priority for LT in patients with a truly low glomerular filtration rate. In this review, we will provide an update on the use of sCr for diagnosis and staging of kidney disease in patients with cirrhosis, discuss the limitations of sCr-based eGFR equations, and discuss novel eGFR equations that have been developed in patients with cirrhosis.

Acute kidney injury defined by cystatin C may be superior for predicting the outcomes of liver cirrhosis with acute gastrointestinal bleeding

BACKGROUND & AIMS

Acute kidney injury (AKI) is conventionally evaluated by a dynamic change of serum creatinine (Scr). Cystatin C (CysC) seems to be a more accurate biomarker for assessing kidney function. This retrospective multicenter study aims to evaluate whether AKI re-defined by CysC can predict the in-hospital outcomes of patients with liver cirrhosis and acute gastrointestinal bleeding.

METHODS

Overall, 677 cirrhotic patients with acute gastrointestinal bleeding, in whom both Scr and CysC levels were detected at admissions, were screened. eGFRScr, eGFRCysC, and eGFRScr-CysC were calculated. MELD-Na score and AKI were re-evaluated by CysC instead of Scr. Odds ratios (ORs) were calculated in the logistic regression analyses. The receiver operating characteristic (ROC) curve analyses were performed.

RESULTS

Univariate logistic regression analyses demonstrated that baseline Scr and CysC levels, eGFRScr, eGFRCysC, eGFRScr-CysC, original MELD-Na score defined by Scr, MELD-Na score re-defined by CysC, and AKI re-defined by CysC, but not conventional AKI defined by Scr, were significantly associated with in-hospital death. ROC analyses showed that baseline CysC level, eGFRScr, eGFRCysC, eGFRScr-CysC, original MELD-Na score defined by Scr, and MELD-Na score re-defined by CysC, but not baseline Scr level, could significantly predict the risk of in-hospital death.

CONCLUSIONS

AKI re-defined by CysC may be superior for predicting the in-hospital mortality of cirrhotic patients with acute gastrointestinal bleeding.

Assessment of glomerular filtration rate in patients with cirrhosis: Available tools and perspectives

Renal dysfunction often complicates the course of liver disease, resulting in higher morbidity and mortality. The accurate assessment of kidney function in these patients is essential to early identify, stage and treat renal impairment as well as to better predict the prognosis, prioritize the patients for liver transplantation and decide whether to opt for simultaneous liver-kidney transplants. This review analyses the available tools for direct or indirect assessment of glomerular filtration rate, focusing on the flaws and strengths of each method in the specific setting of cirrhosis. The aim is to deliver a clear-cut view on this complex issue, trying to point out which strategies to prefer in this context, especially in the peculiar setting of liver transplantation. Moreover, a glance is given at future promising tools for glomerular filtration rate assessment, including new biomarkers and new equations specifically modelled for the cirrhotic population.

Estimation of glomerular filtration rate in patients with cirrhosis: evaluation of equations currently used in clinical practice and validation of Royal Free Hospital cirrhosis glomerular filtration rate

OBJECTIVE

Conventional creatinine-based glomerular filtration rate (GFR) equations have been reported to overestimate renal function in patients with cirrhosis. The Royal Free Hospital (RFH) cirrhosis GFR equation was developed to accurately estimate GFR in this population. The aim of this study was to evaluate the ability of widely available equations [Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI), Modification of Diet in Renal Disease equations (MDRD-4, MDRD-6)] and the RFH equation to correctly estimate the GFR of patients with cirrhosis.

METHODS

We retrospectively analyzed data from patients with cirrhosis who underwent measurement of GFR with the use of 51Cr-EDTA (GFR-M). The CKD-EPI, MDRD-4, MDRD-6 and RFH equations were calculated, while bias, precision and accuracy were estimated for each one of them and then compared with paired t-tests. Bias was defined as the mean difference between the GFR-M and the result of each equation; precision was defined as the SD of the differences and accuracy was defined as the square root of the mean squared error (mean of the squared differences). Higher values are associated with worse bias and better precision/accuracy.

RESULTS

One-hundred and thirty-four cirrhotic patients were included. Bias was estimated for CKD-EPI, MDRD-4, MDRD-6 and RFH at -5.91, -3.13, 0.92 and 18.24, respectively. Significant differences were observed between all equations (P < 0.001). Regarding precision, only the comparison between MDRD-4 (20.81) and RFH (16.6) yielded a statistically significant result (P = 0.037). Finally, CKD-EPI (19.32) and MDRD-6 (18.81) exhibited better accuracy than GFR-RFH (24.61) (P = 0.006 and 0.001).

CONCLUSION

RFH demonstrates inferior accuracy in predicting renal function in patients with cirrhosis, in comparison to conventional equations.

Estimating Glomerular Filtration Rate in Cirrhosis Using Creatinine-Based and Cystatin C-Based Equations: Systematic Review and Meta-Analysis

Accurate estimation of kidney function in cirrhosis is crucial for prognosis and decisions regarding dual-organ transplantation. We performed a systematic review/meta-analysis to assess the performance of creatinine-based and cystatin C (CysC)-based eGFR equations compared with measured GFR (mGFR) in patients with cirrhosis. A total of 25 studies (n = 4565, 52.0 years, 37.0% women) comprising 18 equations met the inclusion criteria. In all GFR equations, the creatinine-based equations overestimated GFR (standardized mean difference, SMD, 0.51; 95% confidence interval [CI], 0.31-0.71) and CysC-based equations underestimated GFR (SMD, -0.3; 95% CI, -0.60 to -0.02). Equations based on both creatinine and CysC were the least biased (SMD, -0.14; 95% CI, -0.46 to 0.18). Chronic kidney disease-Epi-serum creatinine-CysC (CESC) was the least biased but had low precision and underestimated GFR by -3.6 mL/minute/1.73 m² (95% CI, -17.4 to 10.3). All equations significantly overestimated GFR (+21.7 mL/minute/1.73 m² ; 95% CI, 17.7-25.7) at GFR <60 mL/minute/1.73 m² ; of these, chronic kidney disease-Epi-CysC (10.3 mL/minute/1.73 m² ; 95% CI, 2.1-18.4) and GFR Assessment in Liver Disease (12.6 mL/minute/1.73 m² ; 95% CI, 7.2-18.0) were the least biased followed by Royal Free Hospital (15 mL/minute/1.73 m² ; 95% CI, 5.5-24.6) and Modification of Diet in Renal Disease 6 (15.7 mL/minute/1.73 m² ; 95% CI, 10.6-20.8); however, there was an overlap in the precision of estimates, and the studies were limited. In ascites, overestimation of GFR was common (+8.3 mL/minute/1.73 m² ; 95% CI, -3.1 to 19.7). However, overestimation of GFR by 10 to 20 mL/minute/1.73m² is common in patients with cirrhosis with most equations in ascites and/or kidney dysfunction. A tailored approach is required especially for decisions regarding dual-organ transplantation.

Chronic kidney disease in patients with non-alcoholic fatty liver disease: What the Hepatologist should know?

The association of non-alcoholic fatty liver disease (NAFLD) with several other diseases has gained increased interest during the recent years. Among them, the association with chronic kidney disease (CKD) has emerged as an important one regarding both its prevalence and significance. The early recognition of this association is important for the prognosis of patients with NAFLD and CKD. Apart from early diagnosis, the accurate assessment of renal function is also crucial in the clinical practice of hepatologists. Several methods have been used in the literature for the evaluation of kidney function in patients with NAFLD up to now. In this respect, calculators (or formulas) for the estimation of Glomerular Filtration Rate (eGFR) and Albumin to Creatinine Ratio (ACR) are simple, practical and easily available methods for this purpose. The aim of this review is to report on the epidemiology and pathophysiology of the relationship between NAFLD and CKD and to describe the different methods of kidney function assessment in patients with NAFLD. The collection of all relevant data regarding this association will provide hepatologists with pertinent knowledge on this topic and allow them to use the most accurate methods for the assessment of kidney function in these patients in their clinical practice.

Hepatorenal Syndrome Type 1: Current Challenges And Future Prospects

Renal dysfunction represents a dreadful complication of advanced liver cirrhosis. In addition to the traditional types of acute kidney injury (AKI) that can occur in the general population, cirrhotics might experience a different kind of renal dysfunction, called hepatorenal syndrome (HRS). The exact definition of HRS is a functional renal dysfunction caused by overactivity of the endogenous vasoactive systems (in particular intrarenal circulation) which lead to reduced renal perfusion. Type I HRS (HRS-1) is characterized by an abrupt deterioration in renal function (in less than 2 weeks), defined by a doubling of baseline sCr to >2.5 mg/dL or a 50% reduction in the initial 24 hrs creatinine clearance to <20 mL/min. Frequent precipitating events leading to HRS-1 are bacterial infections, gastrointestinal hemorrhage, or large-volume paracentesis without adequate albumin administration as well as massive diuretic use. In 2015, the international club of ascites (ICA) revised the definitions and recommendations concerning HRS. The revised definition allows to adopt effective pharmacological therapy based on albumin and vasoconstrictors in an earlier stage thus not influenced anymore by a rigid sCr cut-off value as by the previous definition of HRS-1. The aim of this article was to provide an updated overview of the latest advancements in the field of hepatorenal syndrome and of the recent amendments of the previous definitions of kidney injury in cirrhotic patients.

Impact of Chronic Kidney Disease on Outcomes in Cirrhosis

We hypothesize that the prevalence of chronic kidney disease (CKD) among patients with cirrhosis has increased due to the increased prevalence of CKD-associated comorbidities, such as diabetes. We aimed to assess the characteristics of hospitalized patients with cirrhosis with CKD and its impact on renal and patient outcomes. The North American Consortium for the Study of End-Stage Liver Disease (NACSELD) prospectively enrolled nonelectively admitted patients with cirrhosis and collected data on demographics, laboratory results, in-hospital clinical course, and postdischarge 3-month outcomes. CKD positive (CKD+) patients, defined as having an estimated glomerular filtration rate (eGFR; Modification of Diet in Renal Disease-4 variable formula) of ≤60 mL/minute for >3 months, were compared with chronic kidney disease negative (CKD-) patients for development of organ failures, hospital course, and survival. There were 1099 CKD+ patients (46.8% of 2346 enrolled patients) who had significantly higher serum creatinine (2.21 ± 1.33 versus 0.83 ± 0.21 mg/dL in the CKD- group) on admission, higher prevalence of nonalcoholic steatohepatitis cirrhosis etiology, diabetes, refractory ascites, and hospital admissions in the previous 6 months compared with the CKD- group (all P < 0.001). Propensity matching (n = 922 in each group) by Child-Pugh scores (9.78 ± 2.05 versus 9.74 ± 2.04, P = 0.70) showed that CKD+ patients had significantly higher rates of superimposed acute kidney injury (AKI; 68% versus 21%; P < 0.001) and eventual need for dialysis (11% versus 2%; P < 0.001) than CKD- patients. CKD+ patients also had more cases of acute-on-chronic liver failure as defined by the NACSELD group, which was associated with reduced 30- and 90-day overall survival (P < 0.001 for both). A 10 mL/minute drop in eGFR was associated with a 13.1% increase in the risk of 30-day mortality. In conclusion, patients with CKD should be treated as a high-risk group among hospitalized patients with cirrhosis due to their poor survival, and they should be monitored carefully for the development of superimposed AKI.

Clinical utility of urinary neutrophil gelatinase-associated lipocalin and serum cystatin C in a cohort of liver cirrhosis patients with renal dysfunction: a challenge in the diagnosis of hepatorenal syndrome

OBJECTIVES

This study aimed to assess urinary neutrophil gelatinase-associated lipocalin (uNGAL) and serum cystatin C (sCys C) in liver cirrhosis patients with renal dysfunction and to evaluate their role in the diagnosis of the hepatorenal syndrome (HRS).

PATIENTS AND METHODS

Forty-five liver cirrhosis patients were enrolled in the study and they were divided into three groups; the first group included 15 patients with normal renal function, the second group included 15 patients with HRS; and the third group included 15 patients with chronic kidney disease (CKD). There was a fourth group, which included 15 healthy controls. Liver and renal function tests, as well as the estimated glomerular filtration rate were determined. uNGAL was measured using the enzyme-linked immunosorbent assay, and the uNGAL/urinary creatinine concentration (UCC) ratio was calculated. sCys C was measured using the particle-enhanced immunoturbidimetric assay.

RESULTS

The ratios of uNGAL and uNGAL/UCC were the highest among HRS patients. The combined uNGAL/UCC ratio and sCys C improved the sensitivity of diagnosis to 93.33% and specificity to 76.67%, with the highest area under the curve of 0.944, 95% confidence interval of 0.879-1.0 (P<0.001). The three biomarkers could successfully identify HRS at the following cutoffs: 84.94 ng/ml, 0.6 ng/mg, and 1.6 mg/l, respectively. Significant positive correlations were found between uNGAL, uNGAL/UCC ratios as well as sCys C and KDIGO stage in liver cirrhosis patients with CKD.

CONCLUSION

uNGAL and a better uNGAL/UCC ratio can be used alone or together with serum cystatin C as early biomarkers for HRS among patients with decompensated liver cirrhosis. Moreover, uNGAL, uNGAL/UCC as well as serum cystatin C could aid the prognostic assessment of cirrhotic patients with CKD.

Unique metabolomic signature associated with hepatorenal dysfunction and mortality in cirrhosis

The application of nontargeted metabolomic profiling has recently become a powerful noninvasive tool to discover new clinical biomarkers. This study aimed to identify metabolic pathways that could be exploited for prognostic and therapeutic purposes in hepatorenal dysfunction in cirrhosis. One hundred three subjects with cirrhosis had glomerular filtration rate (GFR) measured using iothalamate plasma clearance, and were followed until death, transplantation, or the last encounter. Concomitantly, plasma metabolomic profiling was performed using ultrahigh performance liquid chromatography-tandem mass spectrometry to identify preliminary metabolomic biomarker candidates. Among the 1028 metabolites identified, 34 were significantly increased in subjects with high liver and kidney disease severity compared with those with low liver and kidney disease severity. The highest average fold-change (2.39) was for 4-acetamidobutanoate. Metabolite-based enriched pathways were significantly associated with the identified metabolomic signature (P values ranged from 2.07E-06 to 0.02919). Ascorbate and aldarate metabolism, methylation, and glucuronidation were among the most significant protein-based enriched pathways associated with this metabolomic signature (P values ranged from 1.09E-18 to 7.61E-05). Erythronate had the highest association with measured GFR (R-square = 0.571, P <0.0001). Erythronate (R = 0.594, P <0.0001) and N6-carbamoylthreonyladenosine (R = 0.591, P <0.0001) showed stronger associations with measured GFR compared with creatinine (R = 0.588, P <0.0001) even after controlling for age, gender, and race. The 5 most significant metabolites that predicted mortality independent of kidney disease and demographics were S-adenosylhomocysteine (P = 0.0003), glucuronate (P = 0.0006), trans-aconitate (P = 0.0018), 3-ureidopropionate (P = 0.0021), and 3-(4-hydroxyphenyl)lactate (P = 0.0047). A unique metabolomic signature associated with hepatorenal dysfunction in cirrhosis was identified for further investigations that provide potentially important mechanistic insights into cirrhosis-altered metabolism.

Cystatin C Is a Gender-Neutral Glomerular Filtration Rate Biomarker in Patients with Cirrhosis

BACKGROUND

Lower serum Cr levels in women as compared to men result in underestimation of renal dysfunction and lower model for end-stage liver disease-sodium scores leading to reduced access to liver transplantation in women compared to men with comparable hepatic dysfunction.

AIM

The aim of this study was to determine the gender differences in serum Cr, cystatin C, and other endogenous glomerular filtration rate (GFR) biomarkers, measured and estimated GFR, Cr clearance, and Cr production rates.

METHODS

We measured GFR by iothalamate plasma clearance in 103 patients with cirrhosis and assessed gender differences in GFR, Cr clearance and production rate, serum Cr, cystatin C and other endogenous GFR biomarkers including beta-trace protein, beta-2 microglobulin, and dimethylarginines.

RESULTS

Comparison of men and women showed significantly lower values for mean serum Cr (0.97 vs. 0.82 mg/dl, P = 0.023), and Cr production rate (13.37 vs. 11.02 mg/kg/day, P = 0.022). In contrast to the serum Cr and Cr production rate, men and women exhibited no significant differences in the means of serum cystatin C and other GFR biomarkers, measured GFR, GFR estimated using Cr-cystatin C GFR equation for cirrhosis, measured and estimated Cr clearances. After controlling for age, race, weight, height, and GFR, female gender remained associated with lower serum Cr levels (P = 0.003). Serum cystatin C levels were not associated with gender, age, race, weight, height, C-reactive protein, and history of hypothyroidism.

CONCLUSIONS

Our results suggest that cystatin C and endogenous GFR biomarkers other than Cr, measured GFR, GFR estimated by Cr-cystatin C GFR equation for cirrhosis, measured and estimated Cr clearance minimized between-gender biases in accounting for renal function in patients with cirrhosis. Therefore, serum cystatin C should be measured as a complementary test to serum Cr when renal function is assessed in patients with cirrhosis, particularly in women and those with sarcopenia.

New Developments in Hepatorenal Syndrome

Hepatorenal syndrome (HRS) continues to be one of the major complications of decompensated cirrhosis, leading to death in the absence of liver transplantation. Challenges in precisely evaluating renal function in the patient with cirrhosis remain because of the limitations of serum creatinine (Cr) alone in estimating glomerular filtration rate (GFR); current GFR estimating models appear to underestimate renal dysfunction. Newer models incorporating renal biomarkers, such as the Cr-Cystatin C GFR Equation for Cirrhosis appear to estimate measured GFR more accurately. A major change in the diagnostic criteria for HRS based on dynamic serial changes in serum Cr that regard HRS type 1 as a special form of acute kidney injury promises the possibility of earlier identification of renal dysfunction in patients with cirrhosis. The diagnostic criteria of HRS still include the exclusion of other causes of kidney injury. Renal biomarkers have been disappointing in assisting with the differentiation of HRS from prerenal azotemia and other kidney disorders. Serum metabolomic profiling may be a more powerful tool to assess renal dysfunction, although the practical clinical significance of this remains unclear. As a result of the difficulties of assessing renal function in cirrhosis and the varying HRS diagnostic criteria and the rigor with which they are applied, the precise incidence and prevalence of HRS is unknown, but it is likely that HRS occurs more commonly than expected. The pathophysiology of HRS is rooted firmly in the setting of progressive reduction in renal blood flow as a result of portal hypertension and splanchnic vasodilation. Progressive marked renal cortical ischemia in patients with cirrhosis parallels the evolution of diuretic-sensitive ascites to diuretic-refractory ascites and HRS, a recognized continuum of renal dysfunction in cirrhosis. Alterations in nitrous oxide production, both increased and decreased, may play a major role in the pathophysiology of this evolution. The inflammatory cascade, triggered by bacterial translocation and endotoxemia, increasingly recognized as important in the manifestation of acute-on-chronic liver failure, also may play a significant role in the pathophysiology of HRS. The mainstay of treatment remains vasopressor therapy with albumin in an attempt to reverse splanchnic vasodilation and improve renal blood flow. Several meta-analyses have confirmed the value of vasopressors, chiefly terlipressin and noradrenaline, in improving renal function and reversing HRS type 1. Other interventions such as renal replacement therapy, transjugular intrahepatic portosystemic shunt, and artificial liver support systems have a very limited role in improving outcomes in HRS. Liver transplantation remains the definitive treatment for HRS. The frequency of simultaneous liver-kidney transplantation has increased dramatically in the Model for End-stage Liver Disease era, with changes in organ allocation policies. This has resulted in a more urgent need to predict native kidney recovery from HRS after liver transplantation alone, to avoid unnecessary simultaneous liver-kidney transplantation.

Establishing the presence or absence of chronic kidney disease: Uses and limitations of formulas estimating the glomerular filtration rate

The development of formulas estimating glomerular filtration rate (eGFR) from serum creatinine and cystatin C and accounting for certain variables affecting the production rate of these biomarkers, including ethnicity, gender and age, has led to the current scheme of diagnosing and staging chronic kidney disease (CKD), which is based on eGFR values and albuminuria. This scheme has been applied extensively in various populations and has led to the current estimates of prevalence of CKD. In addition, this scheme is applied in clinical studies evaluating the risks of CKD and the efficacy of various interventions directed towards improving its course. Disagreements between creatinine-based and cystatin-based eGFR values and between eGFR values and measured GFR have been reported in various cohorts. These disagreements are the consequence of variations in the rate of production and in factors, other than GFR, affecting the rate of removal of creatinine and cystatin C. The disagreements create limitations for all eGFR formulas developed so far. The main limitations are low sensitivity in detecting early CKD in several subjects, e.g., those with hyperfiltration, and poor prediction of the course of CKD. Research efforts in CKD are currently directed towards identification of biomarkers that are better indices of GFR than the current biomarkers and, particularly, biomarkers of early renal tissue injury.

High mobility group box 1 in diabetic nephropathy

Type 2 diabetes (T2D) is a complex disorder caused by the combined effects of genetic inheritance and environmental factors. The abnormal secretion of albumin via urine is the characteristic feature of a diabetic nephropathy (DN) patient. Moreover, the detection of this observable characteristic feature of DN is quite late. As a result the time, at which DN is observable, large extent of kidney damage has already occurred. Thus, this late observation significantly decreases the chances of efficient management of DN and associated outcomes. The current biomarker used to detect DN is microalbuminuria, the presence of albumin in the urine. However, the current biomarkers often lead to false negative results. The high mobility group box (HMGB)1 is an upcoming molecule being explored for its application in the management of DN. The present review enlightens the current status of HMGB1 in DN.

Development and validation of a mathematical equation to estimate glomerular filtration rate in cirrhosis: The royal free hospital cirrhosis glomerular filtration rate

Current expressions based on serum creatinine concentration overestimate kidney function in cirrhosis, leading to significant differences between "true" and calculated glomerular filtration rate (GFR). We compared the performance of the four-variable and six-variable Modification of Diet in Renal Disease and chronic kidney disease epidemiology with "true," or measured, GFR (mGFR) and the impact of this difference on Model for End-Stage Liver Disease (MELD) calculation. We subsequently developed and validated a GFR equation specifically for cirrhosis and compared the performance of the new derived formula with existing GFR formulae. We included 469 consecutive patients who had a transplant assessment between 2011 and 2014. mGFR was measured using plasma isotope clearance according to a technique validated in patients with ascites. A corrected creatinine was derived from the mGFR after application of the Modification of Diet in Renal Disease formula. Subsequently, a corrected MELD was calculated and compared with the conventionally calculated MELD. Stepwise multiple linear regression was used to derive a GFR equation. This was compared with the mGFR in independent external and internal validation sets of 82 and 174 patients with cirrhosis, respectively. A difference >20 mL/minute/1.73 m2 between existing formulae and mGFR was observed in 226 (48.2%) patients. The corrected MELD score was ≥3 points higher in 177 (37.7%) patients. The predicted equation (r2 = 74.6%) was GFR = 45.9 × (creatinine-0·836 ) × (urea-0·229 ) × (international normalized ratio-0·113 ) × (age-0.129 [Corrected November 29, 2016: originally written as "age-129."]) × (sodium0·972 ) × 0.809 (if female) × 0.92 (if moderate/severe ascites). An online calculator is available at http://rfh-cirrhosis-gfr.ucl.ac.uk. The model was a good fit and showed the greatest accuracy compared to that of existing formulae.

CONCLUSION

We developed and validated a new accurate model for GFR assessment in cirrhosis, the Royal Free Hospital cirrhosis GFR, using readily available variables; this remains to be tested and incorporated in prognostic scores in patients with cirrhosis. (Hepatology 2017;65:582-591).