Evaluation of Gentian cystatin C reagent on Abbott Ci8200 and calculation of glomerular filtration rate expressed in mL/min/1.73 m(2) from the cystatin C values in mg/L

Scand J Clin Lab Invest. 2007;67(5):560-7. doi: 10.1080/00365510601187773.

Abstract

Objective: Estimation of the glomerular filtration rate (GFR) is essential when evaluating patients with kidney disease and treating patients with drugs eliminated from the circulation by the kidneys. Cystatin C has been shown in several studies to be superior to creatinine in the estimation of GFR. At our hospitals, there is an increasing demand for cystatin C and at present we perform approximately 1500 cystatin C analyses a month. We thus need the assay available 24 h/day and to have it on our routine chemistry instrument to minimize handling time per test and time to reported test results.

Material and methods: We have evaluated a new cystatin C immunoassay from Gentian (Gentian, Moss, Norway) on Architect ci8200 (Abbott Laboratories, Abbott Park, Ill., USA). A prerequisite at our hospital is that cystatin C results are reported as a calculated GFR in mL/min/1.73 m(2), so we also made a comparison with iohexol clearance.

Results: The Gentian cystatin C assay showed good agreement with the corresponding assay from Dade Behring (Deerfield, Ill., USA) and good inter-laboratory concordance. The assay has very low total imprecision, good linearity and strong correlation with iohexol clearance (R (2) = 0.956). The equation for the correlation curve is: y = 79.901x(-1.4389).

Conclusions: There was low inter-laboratory variation between the three laboratories involved in the cystatin C evaluation, and thus all three laboratories can use the same equation for calculating the estimated GFR.

Publication types

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

MeSH terms

  • Clinical Laboratory Techniques
  • Cystatin C
  • Cystatins / blood*
  • Glomerular Filtration Rate*
  • Humans
  • Iohexol
  • Kidney / physiology*
  • Kidney Diseases / blood
  • Kidney Diseases / diagnosis
  • Nephelometry and Turbidimetry / instrumentation*
  • Nephelometry and Turbidimetry / methods*
  • Reproducibility of Results

Substances

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