Related Experiment Videos
Cystatin C: an improved estimator of glomerular filtration rate?
Omar F Laterza1, Christopher P Price, Mitchell G Scott
1Washington University School of Medicine, Department of Pathology and Immunology, Division of Laboratory Medicine, Box 8118, 660 S. Euclid Ave., St. Louis, MO 63110, USA.
Insights
Serum creatinine (SCr) is a common marker for kidney function, but cystatin C (CysC) may offer advantages. This review suggests CysC performs at least as well as SCr and may be superior in specific patient groups for assessing glomerular filtration rate (GFR).
Area of Science:
- Nephrology
- Clinical Chemistry
- Biomarker Analysis
Background:
- Glomerular filtration rate (GFR) is crucial for assessing kidney function.
- Current endogenous markers like serum creatinine (SCr) have limitations in certain clinical scenarios.
- Cystatin C (CysC) is an alternative endogenous marker for GFR estimation.
Purpose of the Study:
- To critically review the utility of cystatin C (CysC) for GFR assessment.
- To evaluate CysC's performance, particularly in patient populations where it may outperform SCr.
- To examine the evolution of CysC immunoassays, reference intervals, and diagnostic accuracy.
Main Methods:
- Narrative review of primarily recent publications (last 5 years).
- Medline search (June 2000-September 2001) for studies on CysC and GFR.
- Inclusion criteria: >75 individuals (excluding renal transplant studies) and accepted GFR gold standards.
Main Results:
- CysC levels in blood are independent of age and sex.
- Of 24 studies on clinical utility, 15 found CysC superior to SCr, and 9 found it equivalent.
- Summary ROC analysis of 20 studies indicates CysC is likely superior to SCr for detecting impaired GFR.
Conclusions:
- Cystatin C (CysC) demonstrates at least equivalent performance to serum creatinine (SCr) in the general population.
- CysC is likely superior to SCr for GFR assessment in specific patient subpopulations.
- Further investigation into CysC's role in diverse clinical settings is warranted.
Background:
Glomerular filtration rate (GFR) is routinely assessed by measuring the concentrations of endogenous serum markers such as blood urea nitrogen and serum creatinine (SCr). Although widely used, these endogenous markers are not ideal and do not perform optimally in certain clinical settings. The purpose of this review is to critically review the potential utility of cystatin C (CysC), especially in patient populations in which CysC may have an advantage over routinely used endogenous markers of GFR.
Approach:
In a narrative approach, we extensively review publications, primarily from the last 5 years, that address the development of methods to measure CysC, reference intervals, and the diagnostic accuracy of CysC to assess GFR. Between June 2000 and September 2001 Medline was searched using "cystatin c" as a textword, and articles that examined >75 individuals (except for renal transplant studies) and/or used accepted "gold standards" for assessing GFR were selected for inclusion. A total of 17 studies are reviewed that provide reference interval data for several populations. A total of 24 studies make conclusions about the utility of CysC vs SCr and/or creatinine clearance, with 20 providing data on the sensitivity and specificity of CysC for detecting impaired GFR. These publications are organized into subgroups that deal with specific patient populations or clinical situations.
Content:
This review focuses on two areas: (a) the evolution of immunoassays used to determine the concentration of CysC in serum, their analytic sensitivity, and reference intervals; and (b) the diagnostic performance of CysC against other renal markers in the general population and in specific subpopulations of patients.
Summary:
Studies of reference intervals for CysC overwhelmingly demonstrated that CysC values in blood are independent of age and sex. Of the 24 studies that examined clinical utility, 15 concluded that CysC is superior to SCr, whereas 9 concluded that CysC is equivalent but provides no advantage. Summary ROC plot analysis of 20 studies that provide sensitivity and specificity data strongly suggests that CysC will be superior to SCr for detecting impaired GFR. Taken together, it is clear that CysC performs at least as well as SCr in the population at large and that it is likely to be superior to SCr in specific patient populations.