Variations in assay protocol for the Dako cystatin C method may change patient results by 50% without changing the results for controls
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Mats Flodin
Abstract
Background: Cystatin C is increasingly used as a glomerular filtration marker, but so far only a few companies produce most of the cystatin C reagents suited for turbidimetry or nephelometry use in clinical laboratories.
Methods: We studied different protocols for measuring cystatin C on an Architect ci8200 system using cystatin C reagents from Dako (Glostrup, Denmark). The results were compared with those obtained with Dade Behring reagents (Deerfield, IL, USA) on a BN ProSpec system.
Results: Differences in assay protocol on the same instrument with the Dako reagent yielded an up to 50% difference in glomerular filtration rate calculated from the cystatin C results when analyzing patient samples, but had no effect on the results for controls. There were also significant differences regarding linearity and kinetics between samples and controls/calibrators.
Conclusions: The results indicate different reactivity of the Dako antibodies against calibrators and controls in comparison with patient samples, highlighting the importance of using controls and calibrators that do not differ from patient samples.
Clin Chem Lab Med 2006;44:1481–5.
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©2006 by Walter de Gruyter Berlin New York
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- Contents Volume 44, 2006
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- Subject Index
Artikel in diesem Heft
- Initiation and progression of atherosclerosis – enzymatic or oxidative modification of low-density lipoprotein?
- Blood transfusions in athletes. Old dogmas, new tricks
- Molecular detection of tyrosinase transcripts in peripheral blood from patients with malignant melanoma: correlation of PCR sensitivity threshold with clinical and pathologic disease characteristics
- Increase in and clearance of cell-free plasma DNA in hemodialysis quantified by real-time PCR
- Lipoprotein lipase gene polymorphism at the PvuII locus and serum lipid levels in Guangxi Hei Yi Zhuang and Han populations
- Interpretation of cardiac troponin T behaviour in size-exclusion chromatography
- Point-of-care C-reactive protein testing in febrile children in general practice
- Improvement in HPLC separation of porphyrin isomers and application to biochemical diagnosis of porphyrias
- Measurement of late-night salivary cortisol with an automated immunoassay system
- Combining markers of nephrotoxicity and hepatotoxicity for improved monitoring and detection of chronic alcohol abuse
- Stone or stricture as a cause of extrahepatic cholestasis – do liver function tests predict the diagnosis?
- Insulin resistance and enhanced protein glycation in men with prehypertension
- Prevalence-dependent decision limits for the early detection of type 2 diabetes mellitus in venous blood, venous plasma and capillary blood during glucose challenge
- Analytical performance and clinical utility of the INNOTEST® PHOSPHO-TAU(181P) assay for discrimination between Alzheimer's disease and dementia with Lewy bodies
- Variations in assay protocol for the Dako cystatin C method may change patient results by 50% without changing the results for controls
- Approved IFCC recommendation on reporting results for blood glucose: International Federation of Clinical Chemistry and Laboratory Medicine Scientific Division, Working Group on Selective Electrodes and Point-of-Care Testing (IFCC-SD-WG-SEPOCT)
- National survey on the pre-analytical variability in a representative cohort of Italian laboratories
- 10% CV concentration for the fourth generation Roche cardiac troponin T assay derived from Internal Quality Control data
- Biological variation of non-SI traceable biological quantities: example of proteins
- Effect of tibolone therapy on lipids and coagulation indices
- Acknowledgement
- Contents Volume 44, 2006
- Author Index
- Subject Index
