Improved Immunoturbidimetric Assay for Cystatin C

Ann Clin Biochem. 2001 Mar;38(Pt 2):111-4. doi: 10.1258/0004563011900399.

Abstract

An immunoturbidimetric assay for cystatin C was optimized with respect to assay imprecision. After investigating the optimum pH, polyethylene glycol concentration and specimen volume, two modifications were introduced: an increase in specimen volume to 25 microL; and an extension of the pre-incubation period to 240 s. These modifications produced an assay with between-batch imprecision (coefficient of variation, n = 10 or 11) ranging from 3-9% at 0.72 mg/L to 1.3% at 5.29 mg/L. The assay was susceptible to interference from lipaemia and haemolysis but not bilirubinaemia in both the original and modified protocol. Extending the pre-incubation to 240 s improved tolerance to common interferences and retained assay applicability in the routine clinical setting.

Publication types

  • Evaluation Study

MeSH terms

  • Acid-Base Equilibrium / immunology*
  • Bilirubin / analysis
  • Bilirubin / blood
  • Creatinine / analysis
  • Creatinine / blood
  • Cystatin C
  • Cystatins / analysis*
  • Cystatins / blood
  • Cystatins / chemistry
  • Humans
  • Hydrogen-Ion Concentration
  • Immunoassay / methods
  • Immunoglobulin A / analysis
  • Immunoglobulin A / blood
  • Immunoglobulin A / immunology
  • In Vitro Techniques
  • Kinetics
  • Nephelometry and Turbidimetry / methods*
  • Polyethylene Glycols / chemistry
  • Reagent Kits, Diagnostic
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Temperature
  • Time Factors
  • Triglycerides / analysis
  • Triglycerides / blood
  • Waldenstrom Macroglobulinemia / blood
  • Waldenstrom Macroglobulinemia / immunology

Substances

  • CST3 protein, human
  • Cystatin C
  • Cystatins
  • Immunoglobulin A
  • Reagent Kits, Diagnostic
  • Triglycerides
  • Polyethylene Glycols
  • Creatinine
  • Bilirubin