Clinical evaluation of serum cystatin C and creatinine in patients with chronic kidney disease: A meta-analysis

Performance and pitfalls of the tools for measuring glomerular filtration rate to guide chronic kidney disease diagnosis and assessment

Accurate diagnosis, classification and risk stratification for chronic kidney disease (CKD) allow for early recognition and delivering optimal care. Creatinine-based glomerular filtration rate (GFR), urinary albumin: creatinine ratio (UACR) and the kidney failure risk equation (KFRE) are important tools to achieve this, but understanding their limitations is important for optimal implementation.When accurate GFR is required (eg, chemotherapy dosing), GFR is measured using an exogenous filtration marker. In routine clinical practice, in contrast, estimated GFR (eGFR) from serum creatinine (SCr), calculated using the enzymatic method±UACR, is recommended. Limitations of SCr include non-GFR determinants such as muscle mass, diet and tubular handling. An alternative or additional endogenous filtration marker is cystatin C, which can be used alongside SCr for confirmatory testing of CKD. However, its role in the UK is more limited due to concerns regarding false positive results.The recommended creatinine-based eGFR equation in the UK is the CKD Epidemiology Collaboration 2009 equation. This was recently updated to a race-neutral 2021 version and demonstrated reduced bias in people of Black ethnicity, but has not been validated in the UK. Limitations are extremes of age, inaccuracy at greater GFRs and reduced generalisability to under-represented ethnicity groups.The KFRE (based on age, sex, SCr and UACR) has recently been developed to help determine 2-year and 5-year risk of progression to end-stage kidney disease. It has been validated in over 30 countries and provides meaningful quantitative information to patients. However, supporting evidence for their performance in ethnic minority groups and kidney diseases such as glomerulonephritis remains modest.In conclusion, early identification, risk stratification of kidney disease and timely intervention are important to impact kidney disease progression. However, clinician awareness of the limitations and variability of creatinine, cystatin C and the eGFR equations, is key to appropriate interpretation of results.

How should we assess renal function in neonates and infants?

AIM

Review of current knowledge on assessing renal function in term and preterm neonates.

METHODS

Literature review and analysis of own data.

RESULTS

Prematurity, genetic, environmental and maternal factors may alter peak nephron endowment and life-long renal function. Nephrogenesis continues until 34-36 weeks of gestation, but it is altered with premature delivery. Variability of nephron endowment has a substantial impact on the clearance of renally excreted drugs. Postnatally, glomerular function rate (GFR) increases daily, doubles by two weeks, and slowly reaches full maturity at 18 months of age. Ideally, renal function biomarkers should be expressed as age-independent z-scores, and evidence suggests indexing these values to post-conceptual age rather than chronological age. Newborn and maternal serum creatinine correlate tightly for more than 72 hours after delivery, rendering this biomarker unsuitable for the assessment of neonatal renal function. Cystatin C does not cross the placenta and may be the preferred biomarker in the neonate. Here, we provide preliminary data on the natural evolution of the cystatin C eGFR in infancy.

CONCLUSION

Cystatin C may be superior for GFR estimation in neonates, but the best approach to drug dosing of renally excreted drugs remains to be established.

A Review of Specific Biomarkers of Chronic Renal Injury and Their Potential Application in Nonclinical Safety Assessment Studies

A host of novel renal biomarkers have been developed over the past few decades which have enhanced monitoring of renal disease and drug-induced kidney injury in both preclinical studies and in humans. Since chronic kidney disease (CKD) and acute kidney injury (AKI) share similar underlying mechanisms and the tubulointerstitial compartment has a functional role in the progression of CKD, urinary biomarkers of AKI may provide predictive information in chronic renal disease. Numerous studies have explored whether the recent AKI biomarkers could improve upon the standard clinical biomarkers, estimated glomerular filtration rate (eGFR), and urinary albumin to creatinine ratio, for predicting outcomes in CKD patients. This review is an introduction to alternative assays that can be utilized in chronic (>3 months duration) nonclinical safety studies to provide information on renal dysfunction and to demonstrate specific situations where these assays could be utilized in nonclinical drug development. Novel biomarkers such as symmetrical dimethyl arginine, dickkopf homolog 3, and cystatin C predict chronic renal injury in animals, act as surrogates for GFR, and may predict changes in GFR in patients over time, ultimately providing a bridge from preclinical to clinical renal monitoring.

Pretreatment Serum Cystatin C Levels Predict Renal Function, but Not Tumor Characteristics, in Patients with Prostate Neoplasia

To evaluate the role of Cystatin C (Cys-C) in tumorigenesis and progression of prostate cancer (PCa), we retrospectively collected the clinical information from the records of 492 benign prostatic hyperplasia (BPH), 48 prostatic intraepithelial neoplasia (PIN), and 173 PCa patients, whose disease was newly diagnosed and histologically confirmed. Pretreatment serum Cys-C levels were compared across the various groups and then analyzed to identify relationships, if any, with clinical and pathological characteristics of the PCa patient group. There were no significant differences in serum Cys-C levels among the three groups (P > 0.05). In PCa patients with normal SCr levels, patient age was correlated with serum Cys-C level (P ≤ 0.001) but did not correlate with alkaline phosphatase (AKP), lactate dehydrogenase (LDH), prostate specific antigen (PSA), Gleason score, or bone metastasis status (P > 0.05). Age and SCr contributed in part to the variations in serum Cys-C levels of PCa patients (r = 0.356, P ≤ 0.001; r = 0.520, P ≤ 0.001). In conclusion, serum Cys-C levels predict renal function in patients with prostate neoplasia, but were not a biomarker for the development of prostate neoplasia, and were not correlated with the clinicopathological characteristics of PCa.

The Role of MicroRNA-143-5p in the Differentiation of Dental Pulp Stem Cells into Odontoblasts by Targeting Runx2 via the OPG/RANKL Signaling Pathway

This study aims to elucidate the mechanisms by which microRNA-143-5p (miR-143-5p) targets runt-related transcription factor 2 (Runx2) in the differentiation of dental pulp stem cells (DPSCs) into odontoblasts, through regulating the osteoprotegerin receptor activator of the nuclear factor-κB ligand (OPG/RANKL) signaling pathway. Following transfection, DPSCs were divided into blank, control, miR-143-5p mimics, miR-143-5p inhibitors, miR-143-5p inhibitors + siRunx2 and siRunx2 groups. Alkaline phosphatase (ALP) activity and mineralized nodules were detected using ALP kit and alizarin red staining. Quantitative reverse transcriptase real time PCR (qRT-PCR) was conducted to measure mRNA expressions of miR-143-5p, Runx2, OPG, and RANKL. Western blotting was used to assess protein expression of odontoblast differentiation-related proteins. Transwell assay and an extracellular matrix (ECM) adhesion cell assay were employed to examine cell migration and cell adhesion. Compared with the blank group, the miR-143-5p mimics and siRunx2 groups showed decreased ALP activity, decreased mineralized nodules and displays of calcium. Fewer migrated cells, weakened cell adhesion, decreased protein expression of dentin phosphoprotein (DPP), dentin sialoprotein (DSP), dentin matrix protein 1 (DMP1), osteopontin (OPN), bone sialoprotein (BSP), osteocalcin (OCN), OPG and Runx2, and increased RANKL protein expressions were observed. Additionally, opposite results were observed in the miR-143-5p inhibitors group, demonstrating that down-regulated miR-143-5p promotes the differentiation of DPSCs into odontoblasts by enhancing Runx2 expression via the OPG/RANKL signaling pathway. Based on findings in this study, it is postulated that the enhancement of Runx2 expression via the regulation of the OPG/RANKL signaling pathway could be a beneficial approach for dental pulp regeneration. J. Cell. Biochem. 119: 536-546, 2018. © 2017 Wiley Periodicals, Inc.

Serum Cystatin C as an Inflammatory Marker in Exacerbated and Convalescent COPD Patients

Chronic obstructive pulmonary disease (COPD) is a common chronic inflammatory disease with high morbidity and mortality rates. Cystatin C (Cys C) is a sensitive indicator for various chronic inflammatory diseases. In this study, we aimed to evaluate the role of Cys C in COPD patients comparing with the other well-known inflammatory markers. Ninety patients with acute exacerbated COPD were studied and were reassessed when convalescent. Ninety controls were matched for age, gender, body mass index, smoking index, and comorbidity. Serum Cys C was significantly increased in convalescent COPD patients compared with healthy controls and further increased in COPD patients with an acute exacerbation. Serum Cys C was positively correlated with hsCRP both in the exacerbation and convalescence periods of COPD and negatively correlated with FEV1% predicted and FEV1/FVC in the convalescent COPD patients. In conclusion, serum Cys C is a positive acute-phase reactant in COPD patients and might indicate systemic inflammation during the progression of COPD.

Correlation of cystatin C and creatinine based estimates of renal function in children with hydronephrosis

INTRODUCTION

The use of a simple and accurate glomerular filtration rate (GFR) estimating method aiming minute assessment of renal function can be of great clinical importance.

OBJECTIVES

This study aimed to determine the association of a GFR estimating by equation that includes only cystatin C (Gentian equation) to equation that include only creatinine (Schwartz equation) among children.

PATIENTS AND METHODS

A total of 31 children aged from 1 day to 5 years with the final diagnosis of unilateral or bilateral hydronephrosis referred to Besat hospital in Hamadan, between March 2010 and February 2011 were consecutively enrolled. Schwartz and Gentian equations were employed to determine GFR based on plasma creatinine and cystatin C levels, respectively.

RESULTS

The proportion of GFR based on Schwartz equation was 70.19± 24.86 ml/min/1.73 m(2), while the level of this parameter based on Gentian method and using cystatin C was 86.97 ± 21.57 ml/min/1.73 m(2). The Pearson correlation coefficient analysis showed a strong direct association between the two levels of GFR measured by Schwartz equation based on serum creatinine level and Gentian method and using cystatin C (r = 0.594, P < 0.001). The linear association between GFR values measured with the two methods included cystatin C based GFR = 50.8+ 0.515 × Schwartz GFR. The correlation between GFR values measured by using serum creatinine and serum cystatin C measurements remained meaningful even after adjustment for patients' gender and age (r = 0.724, P < 0.001).

CONCLUSION

The equation developed based on cystatin C level is comparable with another equation, based on serum creatinine (Schwartz formula) to estimate GFR in children.

Usefulness of serum cystatin C to determine the dose of vancomycin in neonate

Purpose

The vancomycin dosage regimen is regularly modified according to the patient's glomerular filtration rate (GFR). In the present study, we aimed to assess the usefulness of serum cystatin C (Cys-C) concentration, compared with serum creatinine (SCr) concentration, for predicting vancomycin clearance (CLvcm) in neonates.

Methods

We retrospectively analyzed the laboratory data of 50 term neonates who were admitted to the neonatal intensive care unit and received intravenous vancomycin, and assessed the pharmacokinetic profiles. Creatinine clearance (CLcr) and GFR based on Cys-C (GFRcys-c) were estimated using the Schwartz and Larsson formulas, respectively.

Results

The mean CLvcm (±standard deviation) was 74.52±31.17 L/hr, the volume of distribution of vancomycin was 0.67±0.14 L, and vancomycin half-life was 9.16±17.42 hours. The SCr was 0.46±0.25 mg/dL and serum Cys-C was 1.43±0.34 mg/L. The peak and trough concentrations of vancomycin were 24.65±14.84 and 8.10±5.35 mcg/mL, respectively. The calculated GFR based on serum creatinine concentration (GFR-Cr) and GFRcys-c were 70.2±9.45 and 63.6±30.18 mL/min, respectively. The correlation constant for CLvcm and the reciprocal of Cys-C (0.479, P=0.001) was significantly higher than that for CLvcm and the reciprocal of SCr (0.286, P=0.044). GFRcys-c was strongly correlated with CLvcm (P=0.001), and the correlation constant was significantly higher than that for CLvcm and CLcr (0.496, P=0.001). Linear regression analysis showed that only GFRcys-c was independently and positively correlated with CLvcm (F=41.9, P<0.001).

Conclusion

The use of serum Cys-C as a marker of CLvcm could be beneficial for more reliable predictions of serum vancomycin concentrations, particularly in neonates.

Cystatin C and cardiovascular or all-cause mortality risk in the general population: A meta-analysis

BACKGROUND

Elevated cystatin C level was associated with excessive risk of cardiovascular events and mortality in the highly cardiovascular risk populations. We conducted this meta-analysis to investigate the relationship between serum cystatin C level and cardiovascular or all-cause mortality risk in the general population.

METHODS

We searched for all relevant studies published through May 2015 using PubMed, Embase, and Cochrane Library. Prospective studies that assessed the relationship between serum cystatin C level and cardiovascular or all-cause mortality risk in the general population were selected. Pooled adjust hazard risk (HR) and the corresponding 95% confidence intervals (CI) were calculated for continuous and category of cystatin C level.

RESULTS

Nine studies composed of 38,854 participants were analyzed. Elevated serum cystatin C level was associated with excessive risk of all-cause mortality (HR 1.72; 95% CI 1.37-2.16) and cardiovascular mortality (HR 2.74; 95% CI 2.04-3.68) comparing the highest to lowest category of cystatin C. Each standard deviation increment in serum cystatin C level increased 32% all-cause (HR 1.32; 95% CI 1.12-1.55) and 57% cardiovascular mortality (HR 1.57; 95% CI 1.31-1.88) risk.

CONCLUSIONS

Elevated serum cystatin C level is independently associated with excessive cardiovascular and all-cause mortality risk in elderly persons.

Renal function overestimation in underweight and/or non-ambulatory patients

Creatinine clearance estimation is widely used to evaluate the renal function of the patients in order to initiate or adjust the drugs dosage. However serum creatinine, as a muscle metabolism by-product, may not be a reliable parameter in underweight and/or non-ambulatory patients, such as geriatric, acquired immunodeficiency syndrome patients and bed-confined and cachexic cases. To avoid overestimation of the renal function in those patients, serum cystatin C can be considered as a sensitive and accurate alternative for serum creatinine.

Mild chronic kidney disease is associated with cognitive function in patients presenting at a memory clinic

OBJECTIVE

In dialysis-dependent and severe chronic kidney disease (CKD) patients, cognitive impairment is found in 16-29%. In community-dwelling population without dementia mixed results have been observed. We investigated the relationship between renal function and cognition in patients from a memory clinic.

METHODS

We performed a cross-sectional study of consecutive patients from a memory clinic between 2005 and 2009. Renal function was estimated with the Modification of Diet in Renal Diseases (MDRD) and Cockcroft-Gault (CG) formulas, and categorized into ordinal groups: reference ≥ 60 ml/min/1.73 m(2), mild CKD 45-59 ml/min/1.73 m(2) and moderate CKD <45 ml/min/1.73 m(2). Cognitive function was dichotomized (Mini-Mental State Examination (MMSE) ≥ 24 vs. <24). We performed multiple logistic regression analyses with adjustment for potential confounders.

RESULTS

The cohort comprised 581 patients (mean age 77 ± 10 years). With the MDRD, there were 74 (12%) cases with moderate CKD and 108 (18%) with mild CKD. With the CG, these prevalences were 144 (30%) and 130 (27%). In mild CKD patients, a significant relationship was found between cognitive function and CKD according to the MDRD-formula [adjusted OR 2.10; 95%CI 1.09-4.05]. In moderate CKD patients, no significant adjusted associations were found. In patients without dementia, significant adjusted associations were found between CKD and MMSE (MDRD: mild CKD [OR 5.09; 95%CI 1.17-22.14] and moderate CKD [OR 5.03; 95%CI 1.10-22.98]; CG: mild CKD [OR 6.16; 95%CI 1.17-32.50] and moderate CKD [OR 5.60; 95%CI 1.01-30.91]).

CONCLUSION

This study showed a significant association between mild CKD and impaired cognitive function in patients from a memory clinic, especially in patients without dementia.

A meta-analysis on diagnostic value of serum cystatin C and creatinine for the evaluation of glomerular filtration function in renal transplant patients

OBJECTIVES

This meta-analysis aimed to perform a systematic review on comparing the diagnostic value of serum cystatin C and creatinine for glomerular filtration rate in renal transplant patients.

METHODS

The data was extracted into 2×2 table after the articles were assessed by the tool of QUADAS and heterogeneity analysis. The SROC curve and meta-analysis were performed by MetaDisc1.4.

RESULTS

Meta-analysis showed that the serum cystatin C had no heterogeneity (P=0.418, I2=2.2%, DOR=25.03), while creatinine heterogeneity was high (P=0.109, I2=37.5%, DOR=9.11). The values of SEN, SPE and SAUC were calculated as 0.86, 0.70 and 0.9015 for cystatin C, and 0.78, 0.73 and 0.8285 for creatinine individually. This study utilized GFR detection and subgroups analysis by cutoff. The PLR was 6.13 and the NLR was 0.12 for cystatin C, compared to SCr (3.72, 0.32). There was homogeneity among these studies using PENIA testing for cystatin C (χ2=2.61, P=0.4560, I2=0.0%.

CONCLUSIONS

There were significant correlations among cystatin C , creatinine and glomerular filtration rate (GFR). Cystatin C had more sensitivity but less specificity than creatinine for evaluation of GFR. Cystatin C had strong ability in diagnosing renal function after renal transplant and ruling out diagnostic efficacy.