Serum Cystatin C Measured by Automated Immunoassay: A More Sensitive Marker of Changes in GFR Than Serum Creatinine

Kidney Int. 1995 Jan;47(1):312-8. doi: 10.1038/ki.1995.40.

Abstract

Serum cystatin C has been suggested as a new marker of GFR. For the introduction of this marker into clinical use a rapid and automated method is required. We have developed and validated an assay for serum cystatin C using latex particle-enhanced immunoturbidimetry. Intra- and inter-assay precision were < 3% and < 5% across the assay range. Analytical recovery was 93 +/- 3.8% and no lack of parallelism was demonstrated. Regression analysis of a method comparison with an enzyme-enhanced radial-immunodiffusion method, gave PETIA = 0.074 + 0.93 x SRID, r = 0.98, N = 100. Inter-assay precision profiles showed cystatin C was measured with two-fold better precision than creatinine on the same analyzer. Cystatin C measurement was neither interfered with by icterus nor by hemolysis. 1/cystatin C versus 1/creatinine concentrations gave r = 0.67, N = 469. Comparison of Cr EDTA GFR with 1/cystatin C and 1/creatinine gave r = 0.81 and 0.50, respectively, N = 206. Calculating diagnostic sensitivity for abnormal GFR showed cystatin C to be significantly (P < 0.05) more sensitive than creatinine (71.4 vs. 52.4%). Cystatin C measurement using PETIA technology can be automated on the same instruments used routinely for the measurement of creatinine and offers better analytical performance and probably improved clinical sensitivity as a screening test for early renal damage.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers
  • Creatinine / blood*
  • Cystatin C
  • Cystatins / blood*
  • Cysteine Proteinase Inhibitors / blood*
  • Glomerular Filtration Rate*
  • Humans
  • Immunoassay / methods*
  • Kidney Diseases / blood*
  • Latex
  • Microspheres
  • Nephelometry and Turbidimetry / methods
  • Reproducibility of Results
  • Sensitivity and Specificity

Substances

  • Biomarkers
  • CST3 protein, human
  • Cystatin C
  • Cystatins
  • Cysteine Proteinase Inhibitors
  • Latex
  • Creatinine