Quantitative automated particle-enhanced immunonephelometric assay for the routinary measurement of human cystatin C

Clin Chem Lab Med. 1998 Nov;36(11):859-65. doi: 10.1515/CCLM.1998.151.


Human cystatin C is a low molecular mass protein of 13359 Dalton recently proposed as a new very sensitive marker of changes in glomerular filtration rate. Serum cystatin C concentration correlates negatively with glomerular filtration rate as well as or better than creatinine. We evaluated a recently introduced automated nephelometric immunoassay for cystatin C in serum or EDTA-plasma samples on the Behring Nephelometer System. The assay consists of incubating the 100-fold diluted sample for 6 minutes with latex particles covalently coated with anti-human cystatin C antibodies, and then quantifying the change of light-scatter produced. Method reproducibility is satisfactory, the intra- and inter-assay coefficients of variation ranging from 1.58% to 3.77% and from 5.6% to 11.47% respectively. Rheumatoid factor (< or = 1116 IU/ml), bilirubin (< or = 418 micrommol/l), triglycerides (10.47 mmol/), and haemoglobin (12 g/l) do not significantly interfere in the assay. No significant difference was found in cystatin C concentration between serum and EDTA-plasma samples. Cystatin C is stable in serum samples stored under different conditions up to one month. This method correlates well (mean difference=-0.536+/-0.307 mg/l) with another commercially available particle-enhanced turbidimetric immunoassay. Cystatin C offers better clinical sensitivity than creatinine for discriminating patients with normal renal function and those with mild-to-moderate reduction in renal function. This method is suitable for routine cystatin C measurement, including emergencies.

MeSH terms

  • Adult
  • Aged
  • Artifacts
  • Creatinine / urine
  • Cystatin C
  • Cystatins / blood*
  • Female
  • Glomerular Filtration Rate
  • Humans
  • Male
  • Middle Aged
  • Nephelometry and Turbidimetry / methods*
  • Reference Values
  • Reproducibility of Results
  • Sensitivity and Specificity


  • CST3 protein, human
  • Cystatin C
  • Cystatins
  • Creatinine