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Problems in the standardization of Factor VIII assays
Scandinavian Journal of Haematology. Supplementum
|January 1, 1980
Summary
Standardizing factor VIII clotting activity (VIII:C) assays is challenging due to reagent differences and assay methods. Current systems show significant discrepancies, impacting reliable measurement of this crucial blood clotting factor.
Area of Science:
- Hematology
- Clinical Chemistry
- Biotechnology
Background:
- An international system for measuring factor VIII clotting activity (VIII:C) exists, based on WHO standards.
- Recent years have seen systematic discrepancies in VIII:C assay results across different laboratories.
Purpose of the Study:
- To identify and analyze the major problems contributing to VIII:C standardization discrepancies.
- To evaluate the impact of assay methods and reagents on VIII:C measurement variability.
Main Methods:
- Analysis of inter-laboratory assay results using the World Health Organization International Standard.
- Comparison of results between one-stage and two-stage VIII:C potency assays.
- Investigation of the role of aluminium hydroxide adsorption in assay discrepancies.
Main Results:
- Significant discrepancies occur between laboratories even with identical assay methods, primarily due to reagent variations.
- A ~20% average discrepancy exists between one-stage and two-stage potency estimates when assaying plasmas against concentrates.
- At least half of the one-stage vs. two-stage discrepancy is linked to aluminium hydroxide adsorption used in the two-stage assay.
Conclusions:
- The current international system for VIII:C standardization has limitations.
- Assay results for factor VIII clotting activity are dependent on both the specific assay method and the reagents employed.
- Reagent variability and differences in assay methodologies (e.g., aluminium hydroxide adsorption) are key factors undermining consistent VIII:C standardization.