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Published on: March 17, 2010
Performance evaluation of a particle-enhanced turbidimetric cystatin C assay on the Hitachi 917 analyzer
M Rabie Al-Turkmani1, Terence Law, Mark D Kellogg
1Department of Laboratory Medicine, Children's Hospital Boston and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, United States.
Background:
Human cystatin C is a low molecular weight protein that has been proposed as a new endogenous marker of glomerular filtration rate. We investigated the performance of the Genzyme cystatin C assay on the Hitachi 917 analyzer.
Methods:
Imprecision, linearity, recovery, and interference studies were performed on the Hitachi 917 analyzer. For method comparison, split sample aliquots were assayed using the described method and 2 other commercially available cystatin C assays.
Results:
The assay was linear from 0.24 to 6.36 mg/l. Within-run coefficient of variation (CV) was 4.2 and 0.8% at cystatin C concentrations of 0.50 and 2.00 mg/l, respectively. Between-run CV was 4.3 and 2.7% at the same concentrations. The average analytical recovery was 99%. Bilirubin (< or =30 mg/dl), triglycerides (< or =1000 mg/dl), intralipid (L index < or =1000), and rheumatoid factor (< or =1000 IU/ml) did not interfere with the assay. A >10% change in cystatin C level was observed when hemoglobin concentration was >800 mg/dl. The assay compared well with the Dade Behring immunonephelometric assay and the Dako immunoturbidimetric assay.
Conclusion:
The Genzyme cystatin C immunoassay is an acceptable method for the determination of cystatin C on the Hitachi 917 analyzer.
