Diagnostic performance of serum cystatin C and serum creatinine in the prediction of chronic kidney disease in renal transplant recipients

Serum Cystatin C in Chronic Kidney Disease: A Case-Control Study

Background: Chronic kidney disease (CKD) is a major public health concern in recent years mainly due to its adverse clinical outcomes. It is most commonly attributed to diabetes mellitus (DM) and hypertension (HTN). Among the several novel biomarkers discovered to detect impaired renal function, serum cystatin C (SCysC) has gained importance. Objectives: The aim of the study was to compare SCysC and serum creatinine (SCr) in CKD subjects and apparently healthy controls. Methods: This case-control study comprising of 120 diagnosed cases of CKD and 40 controls was conducted at a tertiary care hospital. SCr and SCysC levels were estimated using modified Jaffe’s method and particle enhanced immunoturbidimetric method, respectively. Estimated glomerular filtration rate (eGFR) was calculated using CKD EPI formula. Comparison of SCr and SCysC between cases and controls was done using Mann Whitney U test. Pearson’s correlation test was used to study the correlation between variables. Statistical significance was considered at P<0.05. Results: Both SCr and SCysC levels were higher in cases compared to controls (P<0.001). In the group comprising of Stage 1 and Stage 2 CKD subjects, all the subjects showed normal SCr levels, while 96.8% of the subjects showed elevated SCysC levels. SCysC (r=-0.800) showed better correlation than SCr (r=-0.724) with eGFR (P<0.001). A strong correlation was found between SCysC and SCr levels (r=-0.887, P<0.001). Conclusion: SCysC is a good indicator of renal dysfunction and may be used to screen patients with long duration of DM or HTN for CKD.

Association Between Serum Cystatin C and Creatinine in Chronic Kidney Disease Subjects Attending a Tertiary Health Care Centre

INTRODUCTION

Chronic Kidney Disease (CKD) is an emerging health problem due to the increasing prevalence of conditions like diabetes mellitus and hypertension. Most patients are diagnosed during the later stages of CKD when the clinical symptoms become apparent. There is a need for early diagnosis to prevent disease progression and associated morbidities. Serum Creatinine (SCr) is commonly used among clinicians to determine renal function. However, SCr is affected by several factors and cannot be entirely relied upon. In pursuit of an alternative indicator of renal function, several biomarkers have been discovered and their utility in prompt diagnosis has been evaluated. Among such biomarkers, serum cystatin C (SCysC) has been extensively studied.

AIM

To determine and compare the levels of SCr and SCysC in CKD subjects across various severity groups based on estimated Glomerular Filtration Rate (eGFR).

MATERIALS AND METHODS

The study comprised of 120 CKD subjects. SCr was estimated by modified Jaffe's method and SCysC was estimated by particle enhanced immunoturbidimetric method. Estimated GFR (eGFR) was determined using Chronic Kidney Disease Epidemiology collaboration (CKD EPI) 2009 creatinine based formula. Based on eGFR, CKD subjects were further categorized into four groups. Statistical analysis was done using SPSS. Data were represented as median and interquartile range. Kruskal Wallis test was used for comparison between more than two groups. Correlation was done using Pearson's test. Statistical significance was considered as p <0.05.

RESULTS

Both SCr and SCysC levels increased significantly across CKD groups (p<0.001). In CKD subjects with eGFR ≥ 60 ml/min/1.732 m², the median value of SCr (1.01 mg/dl) was well within the normal range while median value of SCysC (1.34 mg/l) was found to be more than the upper reference limit. A positive correlation was present between SCysC and SCr (r=0.875, p<0.001). Both SCysC (r=-0.736) and SCr (r=-0.719) had a negative correlation with eGFR (p<0.001).

CONCLUSION

SCysC is useful in detecting individuals with CKD having mild decrease in GFR compared to SCr. Both SCr and SCysC levels increase with decrease in eGFR. SCysC may be used to screen patients with poorly controlled diabetes mellitus or hypertension when SCr level is inconclusive.