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Comparison of three methods for measuring factor VIII levels in plasma
Wayne L Chandler1, Chris Ferrell, Joo Lee
1Dept of Laboratory Medicine, Box 357110, University of Washington, Seattle, WA 98195, USA.
American Journal of Clinical Pathology
|July 18, 2003
Summary
The chromogenic assay is the best method for measuring elevated factor VIII levels in plasma. It offers superior precision and correlation, unaffected by common interfering substances.
Area of Science:
- Hematology
- Clinical Chemistry
- Coagulation Diagnostics
Background:
- Accurate measurement of factor VIII (FVIII) is crucial for diagnosing and managing bleeding disorders.
- Elevated FVIII levels are associated with thrombotic risk, necessitating reliable quantification methods.
Purpose of the Study:
- To compare the performance of 1-stage clot-based, chromogenic, and immunoassay methods for measuring plasma factor VIII.
- To identify the optimal assay for quantifying elevated factor VIII levels and assess interference effects.
Main Methods:
- Comparative analysis of three distinct factor VIII measurement techniques: 1-stage clot-based, chromogenic, and immunoassay.
- Evaluation of interassay imprecision, correlation coefficients (r²), and interference from common anticoagulants and inhibitors.
Main Results:
- The chromogenic assay demonstrated the best interassay precision for factor VIII levels around 150 IU/dL.
- Highest correlation was observed between 1-stage clot-based and chromogenic assays (r² = 0.934).
- The 1-stage clot-based assay showed significant interference from heparin, low-molecular-weight heparin, lepirudin, and lupus inhibitors, unlike the chromogenic and antigenic assays.
Conclusions:
- The chromogenic factor VIII activity assay is the optimal method for measuring elevated factor VIII levels.
- It provides superior precision, strong correlation with other methods, and is robust against common interfering substances.