HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (14) Citing Articles via Google Scholar Google Scholar Articles by Stowe, H. Articles by Lamb, E. J. Search for Related Content PubMed PubMed Citation Articles by Stowe, H. Articles by Lamb, E. J. Related Collections Proteomics and Protein Markers Automation and Analytical Techniques

Analytical Performance of a Particle-enhanced Nephelometric Immunoassay for Serum Cystatin C Using Rate Analysis

¹ Department of Clinical Biochemistry, East Kent Hospitals NHS Trust, Kent and Canterbury Hospital, Ethelbert Road, Canterbury CT1 3NG, Kent, United Kingdom

² The South West Thames Institute for Renal Research, St. Helier’s Hospital, Carshalton SM5 1AA, Surrey, United Kingdom

^aauthor for correspondence: fax 44-1227-783077, e-mail edmund.lamb@kch-tr.sthames.nhs.uk

The serum cystatin C concentration reflects glomerular filtration and, as a marker of renal disease, demonstrates improved accuracy and sensitivity compared with serum creatinine (1)(2)(3). Several assays (4) have been described for cystatin C, including latex particle-enhanced nephelometric immunoassays (PENIAs) (5) and turbidimetric immunoassays (PETIAs) (2)(3). The PETIA marketed by Dako Ltd (cat. no. K 0071; Ely, United Kingdom) has been adapted to a variety of automated analyzers that use fixed-interval turbidimetric measurement (6)(7). However, the analytical performance initially described for this method (2) has not always been replicated. Compared with the PENIA developed for the Dade Behring (Milton Keynes, United Kingdom) nephelometers [e.g., the Behring Nephelometer II (BNII)], the PETIA demonstrates high imprecision at the upper limit of the reference interval (6)(8)(9) and susceptibility to spectral interferences (4). On a Cobas Mira S Plus analyzer, these reagents were subject to interference from bilirubin (>270 µmol/L), hemoglobin (>4 g/L), and triglycerides (>5.7 mmol/L), and between-day imprecision (CV) exceeded 8% at 1.10 and 4.10 mg/L (10).

We describe the measurement of cystatin C using an adaptation of these reagents in a nephelometric immunoassay using kinetic rate analysis. All analyses were performed with a single batch of reagent on an automated rate nephelometer (Immage^TM analyzer; Beckman-Coulter Ltd., High Wycombe, United Kingdom). Recombinant human cystatin C calibrators supplied by the manufacturer were used, and an additional calibrator was prepared by diluting (1:1) the calibrator with the lowest cystatin C concentration (0.39 mg/L) in phosphate buffer, pH 7.0 (cat. no. 447640; Beckman-Coulter Ltd.). The calibrator with the highest concentration (12.3 mg/L) was not used. Analyses were performed in user-defined mode, using provisional settings provided . . . [Full Text of this Article]

Acknowledgments

References

The following articles in journals at HighWire Press have cited this article:

				E. J. Lamb, H. J. Stowe, D. E. Simpson, A. J. Coakley, D. J. Newman, and M. Leahy Diagnostic Accuracy of Cystatin C as a Marker of Kidney Disease in Patients with Multiple Myeloma: Calculated Glomerular Filtration Rate Formulas Are Equally Useful Clin. Chem., October 1, 2004; 50(10): 1848 - 1851. [Full Text] [PDF]