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

Optimal Glomerular Filtration Rate Equations for Various Age Groups, Disease Conditions and Ethnicities in Asia: A Systematic Review

(1) Background: The performance of estimated glomerular filtration rate (eGFR) equations in the Asian population has been widely questioned. The primary objective of this study was to gather evidence regarding optimal GFR equations in Asia for various age groups, disease conditions, and ethnicities. The secondary objective was to see whether the equations based on the combination of creatinine and cystatin C biomarkers if employed are satisfactory across different age groups and disease conditions in various ethnicities in Asia compared to those based on either of the single biomarkers. (2) Methods: Validation studies that had both creatinine and cystatin C-based equations either alone or in combination, validated in specific disease conditions, and those which compared the performance of these equations with exogenous markers were eligible only. The bias, precision, and 30% accuracy (P30) of each equation were recorded accordingly. (3) Results: Twenty-one studies consisting of 11,371 participants were included and 54 equations were extracted. The bias, precision, and P30 accuracies of the equations ranged from -14.54 to 9.96 mL/min/1.73 m2, 1.61 to 59.85 mL/min/1.73 m2, and 4.7% to 96.10%. The highest values of P30 accuracies were found for the JSN-CKDI equation (96.10%) in Chinese adult renal transplant recipients, for the BIS-2 equation (94.5%) in Chinese elderly CKD patients, and Filler equation (93.70%) also in Chinese adult renal transplant recipients. (4) Conclusions: Optimal equations were identified accordingly and it was proven that combination biomarker equations are more precise and accurate in most of the age groups and disease conditions. These can be considered equations of choice for the specific age groups, disease conditions, and ethnicities within Asia.

The ratio of creatinine and cystatin C estimated glomerular filtration rates as a surrogate marker in patients with hepatocellular carcinoma undergoing hepatic resection

BACKGROUND

The ratio of creatinine and cystatin C estimated glomerular filtration rates (eGFRcre/eGFRcys) is significantly positively correlated with sarcopenia. However, there are no published reports on the relationship between eGFRcre/eGFRcys and long-term prognosis in patients after hepatic resection for hepatocellular carcinoma (HCC).

METHODS

157 patients who had undergone curative hepatic resection for HCC were retrospectively reviewed. Cystatin C levels were measured in serum samples that had been frozen after collection at surgery. We aimed to investigate the significance of cystatin C in prognostic value following hepatic resection for HCC.

RESULTS

The best cut-off eGFRcre/eGFRcys value for overall survival after hepatic resection for HCC was 1.0025. High eGFRcre/eGFRcys was significantly associated with poor liver function, low skeletal muscle mass, large tumor size, large ascitic volume, worse overall and recurrence-free survival. The eGFRcre/eGFRcys was significantly related to severe recurrence patterns (multiple liver recurrences, distant metastasis).

CONCLUSIONS

Preoperative eGFRcre/eGFRcys can predict overall and recurrence-free survival in HCC patients undergoing hepatic resection. The eGFRcre/eGFRcys is a simple and reliable surrogate marker that indicate for eligibility for hepatic resection for HCC.

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.

Comparative study of various glomerular filtration rate estimating equations in Egyptian patients with hepatitis C virus-related liver cirrhosis: a single-center observational study

Background

Accurate assessment of GFR is critical in patients with chronic liver disease for early detection of renal disease. Cystatin C is a marker of GFR that seems to be more accurate than creatinine. The aim of the study is to assess of the performance of creatinine and cystatin C-based GFR equations in Egyptian patients with hepatitis C virus (HCV)-related liver cirrhosis as compared to measured creatinine clearance. GFR was estimated using five equations; three that were based on serum creatinine, another that was based on serum cystatin C, and a third that was based on both in 120 patients with HCV-related liver cirrhosis as well as 60 age- and sex-matched healthy controls. The bias, precision, and accuracy of each equation were determined as compared to measured creatinine clearance using the traditional equation U*V/P.

Results

The mean measured creatinine clearance was 51.39 ± 16.05 ml/min per 1.73 m2. The CKD-EPI creatinine-cystatin C equation had the greatest precision (7.5 ml/min per 1.73 m2), and highest accuracy (68 and 93% within 10% and 30% of measured GFR, respectively), but not the lowest bias (5.4 ml/min per 1.73 m2). The CKD-EPI creatinine-cystatin C equation remained accurate even in both males (69 and 90% within 10% and 30% of measured GFR, respectively) and females (68 and 97% within 10% and 30% of measured GFR, respectively). The CKD-EPI creatinine-cystatin C equation remained accurate even when the measured GFR was ≥ 60 ml/min per 1.73 m2 (60 and 90% within 10% and 30% of measured GFR, respectively with precision 10.5 ml/min per 1.73 m2).

Conclusion

CKD-EPI creatinine-cystatin C equation is more accurate at predicting GFR in HCV-related liver cirrhosis than creatinine- and cystatin-C alone based equations.

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.

Prognostic Value of Pretreatment Serum Cystatin C Level in Nasopharyngeal Carcinoma Patients in the Intensity-modulated Radiotherapy Era

Purpose

Serum cystatin C has been considered as a significant prognostic factor for various malignancies. This study aimed to evaluate the relationship between serum cystatin C level before antitumor treatment and the prognosis of nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT).

Patients and Methods

A cohort of 2077 NPC patients were enrolled between April 2009 and September 2012. The Kaplan–Meier curves and log rank tests were used to determine the differences of overall survival (OS) and disease-free survival (DFS). Univariate and multivariate Cox regression analyses were used to determine independent prognostic factors.

Results

Overall, 362/2077 (17.4%) patients had high serum cystatin C level, and they were older and more male (both P<0.001), and they had higher TNM stage (all P<0.05). Kaplan–Meier analysis revealed that patients with high serum cystatin C had worse OS (P<0.001) and DFS (P<0.001). Univariate and multivariate Cox regression analysis showed that high serum cystatin C level was an independent prognostic predictor of OS (HR: 1.56, 95%CI: 1.25–1.95) and DFS (HR: 1.38, 95%CI: 1.13–1.68). Subgroup analysis based on TNM stage revealed that advanced-stage NPC patients with high serum cystatin C had poorer OS (P<0.001) and DFS (P<0.001).

Conclusion

Our results revealed that high serum cystatin C level before antitumor treatment can predict clinical outcomes of NPC patients treated with IMRT, and it can guide clinicians to formulate more personalized therapy for NPC patients.

Cystatin C as a biomarker of chronic kidney disease: latest developments

INTRODUCTION

Chronic kidney disease (CKD) is common, occurring in over 10% of individuals globally, and is increasing in prevalence. The limitations of traditional biomarkers of renal dysfunction, such as serum creatinine, have been well demonstrated in the literature. Therefore, augmenting clinical assessment with newer biomarkers, such as serum cystatin C, has the potential to improve disease monitoring and patient care.

AREAS COVERED

The present paper assesses the utility and limitations of serum cystatin C as a biomarker for CKD in light of the current literature.

EXPERT OPINION

Serum cystatin C has been well established as an early and accurate biomarker of CKD that is particularly helpful in patients for whom creatinine is an inadequate marker or for whom more cumbersome methods of glomerular filtration rate (GFR) measurement are impractical. Current research questions are no longer focused on if, but rather when and how often cystatin C should be used in the evaluation of CKD patients. However, transition of all reagents and estimated GFR equations to the newly established International Standard is critical for developing generalizable data.

Effect of terlipressin on renal function in cirrhotic patients with acute upper gastrointestinal bleeding

BACKGROUND

Renal dysfunction is a serious morbidity in cirrhotic patients with acute upper gastrointestinal bleeding (AUGIB). Terlipressin is the first-line treatment choice for acute variceal bleeding and hepatorenal syndrome (HRS). This study aimed to assess the effect of terlipressin on renal function in patients with liver cirrhosis and AUGIB.

METHODS

We retrospectively reviewed 40 cirrhotic patients with AUGIB treated with terlipressin by an attending physician between January 2016 and June 2018. We analyzed the change of renal function parameters, including cystatin C (CysC) and creatinine (Cr), during the use of terlipressin and after terlipressin was stopped. We also identified the factors associated with renal function improvement in patients without active bleeding during the use of terlipressin.

RESULTS

During the use of terlipressin, CysC value was significantly reduced (1.3±0.8 vs. 1.1±0.7, P=0.001); Cr value was reduced, but the reduction was not statistically significant (68.8±24 vs. 65.5±23, P=0.817); the rate of CysC reduction was significantly higher in patients treated with terlipressin than those treated with somatostatin/octreotide (73.1% vs. 0%, P=0.005); the rate of Cr reduction was not significantly different between patients treated with terlipressin and somatostatin/octreotide (61.5% vs. 20%, P=0.148); no factor associated with CysC reduction was identified; higher hemoglobin, red blood cell, and platelet and lower prothrombin time and international normalized ratio at baseline were significantly associated with Cr reduction. After terlipressin was stopped, neither CysC nor Cr value was significantly reduced (P=0.852 and P=0.296).

CONCLUSIONS

Terlipressin may be beneficial on preventing renal function impairment in cirrhotic patients with AUGIB.

How to estimate renal function in patients with liver disease: choosing the most suitable equation

BACKGROUND

Hepatitis B virus (HBV) infection is a public health challenge, especially in China. In clinical practice, HBV infection is associated with nephropathy. Impaired renal function is frequently observed in compensated Chronic Hepatitis B (CHB) and cirrhosis (LC). Thus, renal function must be monitored to avoid nephrotoxic effects before and during nucleoside analog treatment. Investigating the predictive markers of early renal dysfunction is essential. New GFR-predicting equations, based on Pcr and/or CystC, have been recently recommended in the general population, but their performance in liver disease patients has been rarely studied. In this study, we will discuss how to detect renal dysfunction in patients with HBV infection.

METHODS

A total of 16 LC patients and 23 CHB patients were enrolled in this study, and we collected and compared the clinical data of the two groups. The estimated glomerular filtration rates (eGFRs) were also calculated by several equations. All patients received 99mTc-DTPA dynamic radionuclide imaging examinations to obtain mGFRs as the reference standard. To evaluate the performance of any equation in the CHB and LC groups, paired t test, Pearson's correlation, Kappa analysis and Bland-Altman plots were utilized. Moreover, all 39 subjects were divided into two groups (according to GFR > 90 mL/min/1.73 m²). We compared the serum and urinary markers of kidney injury between the two groups and selected the indicators of renal injury by univariate analysis.

RESULTS

The mGFR was 72.26 ± 20.69 mL/min/1.73 m² in the LC group, and 87.49 ± 25.91 mL/min/1.73 m² in the CHB group. The paired t test results of eGFR and mGFR showed no difference between eGFR (estimated by the CHINAcr-cys equation) and mGFR (p > 0.05) in the compensated LC and CHB groups. The difference between mGFR and eGFR estimated by other methods was obvious (p < 0.05). Comparing the eGFRs (estimated by 5 different equations) with mGFR in the compensated LC and CHB groups, Pearson's correlation showed that only eGFR (estimated by the CHINAcr-cys equation) had a significant correlation coefficient in CHB (r = 0.678, p = 0.000) and had the highest R² (R² = 0.459) among all other measures. The kappa consistency test showed that eGFR from CHINAscr-cys had poor consistency with mGFR in the compensated LC group but moderate consistency in the CHB group. Bland-Altman consistency analysis showed that in the CHB group, the CHINAcr-cys and CKD-EPIcr equations presented narrower acceptable limits than did the aMDRD, c-aMDRD, and CKD-EPIcr-cys equations (62.8, 56.1 vs .85.7, 102.9, 93.6 mL/min per 1.73 m²). In the compensated LC group, the CHINAcr-cys and CKD-EPIcr equations presented narrower acceptable limits than did the aMDRD, c-aMDRD, and CKD-EPIcr-cys equations (83.6, 81.3 vs. 98, 113.5, 106.3 mL/min per 1.73 m²). Serum or urinary markers were compared with renal function (GFR > 90 mL/min/1.73 m²) and showed International normalized ratio (INR) (p = 0.009), creatinine (p = 0.006), urine N-acetyl-β-glucosaminidase (NAG) (p = 0.001) and serum cystatin C (CysC) (p = 0.044).

CONCLUSION

The CHINAcr-cys equation may be more suitable for the estimation of GFR in Chinese patients with CHB or compensated cirrhosis. INR, creatinine, NAG, and CysC are proper biomarkers for screening renal dysfunction in Chinese patients with CHB or compensated LC.

Serum NGAL Is Superior to Cystatin C in Predicting the Prognosis of Acute-on-Chronic Liver Failure

INTRODUCTION AND AIM

Acute-on-chronic liver failure (ACLF) is a syndrome with high short-term mortality, and predicting the prognosis is challenging. This study aimed to compare the performance of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C (CysC) in predicting the 90-day mortality in patients with hepatitis B virus (HBV)-associated ACLF (HBV-ACLF).

MATERIALS AND METHODS

This prospective, observational study enrolled 54 patients with HBV-ACLF. The serum NGAL and CysC levels were determined. A multivariate logistic regression analysis was used to analyze the independent risk factors of mortality.

RESULTS

Serum NGAL, but not CysC, was found to significantly correlate with the total bilirubin, international normalized ratio, and model for end-stage liver disease (MELD). Serum NGAL [odds ratio (OR), 1.008; 95% confidence interval (CI), 1.004-1.012; P < 0.01], but not CysC, was an independent risk factor for developing hepatorenal syndrome. Moreover, NGAL (OR, 1.005; 95% CI, 1.001-1.010; P < 0.01) along with the MELD score was independently associated with the overall survival in patients with HBV-ACLF. Patients with HBV-ACLF were stratified into two groups according to the serum NGAL level at baseline (low risk: <217.11 ng/mL and high risk: ≥ 217.11 ng/mL). The 90-day mortality rate was 22.73% (5/22) in the low-risk group and 71.88% (23/32) in the high-risk group. Moreover, NGAL, but not CysC, significantly improved the MELD score in predicting the prognosis of HBV-ACLF.

CONCLUSION

The serum NGAL might be superior to CysC in predicting the prognosis of HBV-ACLF with the normal creatinine level.

Educational review: measurement of GFR in special populations

IMPORTANCE

Changes in kidney function are typically followed by the sequential estimation of glomerular filtration rate (eGFR). Formulae for eGFR work well on a population basis, but there are well-known conditions where they do not work.

OBJECTIVE

The purpose of this review is to summarize the existing literature on special populations in the pediatric age range and provide recommendations on how to estimate GFR in these populations.

FINDINGS

The reliability of creatinine depends on muscle mass, while cystatin C (not widely available) is limited by inflammation and changes in protein catabolism. Various dietary factors can alter eGFR. Renal function in neonates changes drastically every day, and there are currently no satisfactory reference intervals for routine pediatric use. Gender effects and conditions such as wasting disease and obesity require alternative ways to obtain eGFR. In oncology patients, chemotherapy may negatively affect renal function, and nuclear GFR measurements may be necessary. For body builders, high muscle mass may lead to underestimation of eGFR using creatinine.

CONCLUSIONS AND RELEVANCE

Clinicians should be aware of special populations that may yield misleading eGFRs with conventional creatinine-based formulae, and that the alternative methods may be more appropriate for some populations.

Serum cystatin C level: An excellent predictor of mortality in patients with cirrhotic ascites

BACKGROUND AND AIM

Although serum cystatin C level is considered a more accurate marker of renal function in patients with liver cirrhosis, its prognostic efficacy remains uncertain. This study aimed to evaluate the prognostic efficacy of serum cystatin C level in patients with cirrhotic ascites.

METHODS

Patients with cirrhotic ascites from 15 hospitals were prospectively enrolled between September 2009 and March 2013. Cox regression analyses were performed to identify independent predictive factors of mortality and development of type 1 hepatorenal syndrome (HRS-1).

RESULTS

In total, 350 patients were enrolled in this study. The mean age was 55.4 ± 10.8 years, and 267 patients (76.3%) were men. The leading cause of liver cirrhosis was alcoholic liver disease (64.3%), followed by chronic viral hepatitis (29.7%). Serum creatinine and cystatin C levels were 0.9 ± 0.4 mg/dL and 1.1 ± 0.5 mg/L, respectively. Multivariate analyses revealed that international normalized ratio and serum bilirubin, sodium, and cystatin C levels were independent predictors of mortality and international normalized ratio and serum sodium and cystatin C levels were independent predictors of the development of HRS-1. Serum creatinine level was not significantly associated with mortality and development of HRS-1 on multivariate analysis.

CONCLUSION

Serum cystatin C level was an independent predictor of mortality and development of HRS-1 in patients with cirrhotic ascites, while serum creatinine level was not. Predictive models based on serum cystatin C level instead of serum creatinine level would be more helpful in the assessment of the condition and prognosis of patients with cirrhotic ascites.

Plasma cystatin C is a predictor of renal dysfunction, acute-on-chronic liver failure, and mortality in patients with acutely decompensated liver cirrhosis

The development of acute-on-chronic liver failure (ACLF) in patients with liver cirrhosis is associated with high mortality rates. Renal failure is the most significant organ dysfunction that occurs in ACLF. So far there are no biomarkers predicting ACLF. We investigated whether cystatin C (CysC) and neutrophil gelatinase-associated lipocalin (NGAL) can predict development of renal dysfunction (RD), hepatorenal syndrome (HRS), ACLF, and mortality. We determined the plasma levels of CysC and NGAL in 429 patients hospitalized for acute decompensation of cirrhosis in the EASL-CLIF Acute-on-Chronic Liver Failure in Cirrhosis (CANONIC) study. The patients were followed for 90 days. Patients without RD or ACLF at inclusion but with development of either had significantly higher baseline concentrations of CysC and NGAL compared to patients without. CysC, but not NGAL, was found to be predictive of RD (odds ratio, 9.4; 95% confidence interval [CI], 1.8-49.7), HRS (odds ratio, 4.2; 95% CI, 1.2-14.8), and ACLF (odds ratio, 5.9; 95% CI, 1.3-25.9). CysC at day 3 was not found to be a better predictor than baseline CysC. CysC and NGAL were both predictive of 90-day mortality, with hazard ratios for CysC of 3.1 (95% CI, 2.1-4.7) and for NGAL of 1.9 (95% CI, 1.5-2.4).

CONCLUSION

Baseline CysC is a biomarker of RD, HRS, and ACLF and an independent predictor of mortality in patients with acutely decompensated liver cirrhosis, though determining CysC at day 3 did not provide any benefit; while NGAL is also associated with short-term mortality, it fails to predict development of RD, HRS, and ACLF. Baseline CysC may help to identify patients at risk earlier and improve clinical management. (Hepatology 2017;66:1232-1241).

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.

Role of Cystatin C and glomerular filtration rate in diagnosis of kidney impairment in hepatic cirrhosis patients

Hepatic cirrhosis is often accompanied by functional kidney impairment, which may be reversed if early treatment is promptly administered. This study aimed to investigate the role of Cystatin C and Cystatin C estimated glomerular filtration rate in the diagnosis of kidney impairment in patients with hepatic cirrhosis.Four hundred sixty five patients with hepatic cirrhosis were recruited. Serum creatinine and Cystatin C were determined, and their estimated glomerular filtration rates were calculated.The area under the receiver-operating characteristic curve (area under curve [AUC]) of Cystatin C and Cystatin C estimated glomerular filtration rate was significantly larger than that of serum creatinine and serum creatinine estimated glomerular filtration rate, respectively (P = .000). When the optimal cut-off value and upper reference limit were used, similar sensitivity, misdiagnosis rate, and diagnostic consistency were only observed in Cystatin C estimated glomerular filtration rate (P > .05).Cystatin C and Cystatin C estimated glomerular filtration rate are superior to serum creatinine and serum creatinine estimated glomerular filtration rate in diagnosis of secondary kidney impairment, and Cystatin C estimated glomerular filtration rate has a better performance as compared with Cystatin C. However, it is not a measured parameter, and thus the lab should determine its own optimal cut-off value.

Comparison of Performance of Improved Serum Estimators of Glomerular Filtration Rate (GFR) to 99mTc-DTPA GFR Methods in Patients with Hepatic Cirrhosis

Glomerular filtration rate (GFR) measurements are critical in patients with hepatic cirrhosis but potentially erroneous when based on serum creatinine. New equations for estimated GFR (eGFR) have shown variable performance in cirrhotics, possibly because of inaccuracies in reference methods for measured GFR (mGFR). The primary objective was to compare the performance of 4 improved eGFR equations with a 1-compartment, 2-sample plasma slope intercept ^99mTc-DTPA mGFR method to determine whether any of the eGFR calculations could replace plasma ^99mTc-DTPA mGFR in patients with cirrhosis. The secondary objective was to test the hypothesis that mGFR using voluntary voided urine collections introduces error compared with plasma-only methods. Methods: Fifty-four patients with hepatic cirrhosis underwent mGFR determinations from 2 plasma samples at 1 and 3 h after intravenous administration of 185 MBq of ^99mTc-DTPA. GFR was also generated by a UV/P calculation derived from blood and urine samples. These mGFRs were compared with the eGFRs generated by 4 estimating equations: MDRD (Modified Diet in Renal Disease), CKD-EPI (Chronic Kidney Disease-Epidemiology Collaboration) (serum creatinine [SCr]), CKD-EPI (cystatin [CysC]), and CKD-EPI (CysC+SCr). eGFRs were compared with mGFRs by Pearson correlation, precision, bias, percentage bias, and accuracy (eGFRs varying by <10% [p10], <20% [p20] or <30% [p30] from the corresponding mGFR). Results: All eGFRs showed poorer performance when the UV/P ^99mTc-DTPA mGFR was used as the reference than when the plasma ^99mTc-DTPA mGFR was used. When compared with the plasma ^99mTc-DTPA mGFR method, the performance of all eGFR equations was superior to most published reports. There was a moderately good positive correlation between eGFRs and mGFRs. When compared with plasma ^99mTc-DTPA mGFR, precision of eGFRs was in the range of 14-20 mL/min and showed a negligible bias. Compared with the plasma ^99mTc-DTPA mGFR, CKD-EPI (CysC+SCr) showed the best overall performance and accuracy, at 85.19% (p30), 75.93% (p20), and 42.59% (p10). Conclusion: Estimating equations for measuring eGFR performed better than in most published reports, attributable to use of the plasma ^99mTc-DTPA mGFR method as a reference. CKD-EPI (CysC+SCr) eGFR showed the best overall performance. However, more discriminating methods may be required when accurate GFR measurements are necessary. mGFR measurements using urine collections may introduce error compared with plasma-only methods.

Evaluation of Serum Cystatin C as a Marker of Early Renal Impairment in Patients with Liver Cirrhosis

Background. Serum cystatin C (CysC) was proposed as an effective reflection of the glomerular filtration rate (GFR). However, its role in patients with liver cirrhosis has not been extensively verified especially in the detection of early RI. Patients and Methods. Seventy consecutive potential candidates for living donor liver transplantation with serum creatinine (Cr) <1.5 mg/dL were included. CysC, Cr, and estimated GFR [creatinine clearance (CCr), Cockcroft-Gault formula (C-G), MDRD equations with 4 and 6 variables, CKD-EPI-Cr, CKD-EPI-CysC, and CKD-EPI-Cr-CysC] were all correlated to isotopic GFR. Early RI was defined as GFR of 60-89 mL/min/1.73 m(2). Results. Patients were 25.7% and 74.3% Child-Pugh classes B and C, respectively. GFR was ≥90, 60-89, and 30-59 mL/min/1.73 m(2) in 31.4%, 64.3%, and 4.3% of the patients, respectively. All markers and equations, except C-G, were significantly correlated to GFR with CKD-EPI-Cr-CysC formula having the highest correlation (r = 0.474) and the largest area under the ROC curve (0.808) for discriminating early RI. At a cutoff value of 1.2 mg/L, CysC was 89.6% sensitive and 63.6% specific in detecting early RI. Conclusion. In patients with liver cirrhosis, CysC and CysC-based equations showed the highest significant correlation to GFR and were measures that best discriminated early RI.