Biomaterial Database

Problems in the standardization of Factor VIII assays. 1980

T B Kirkwood

An international system of unitage, based on the World Health Organization International Standard, exists for the measurement of factor VIII clotting activity (VIII: C). In recent years, systematic discrepancies between assay results in different laboratories have brought to light two major problems in VIII: C standardization. Firstly, large discrepancies can arise between laboratories even when the same assay method is used. These are due mainly to differences in reagents. Secondly, when assaying plasmas against concentrates, there is, on average, a 20% discrepancy between one-stage and two-stage potency estimates. At least half this discrepancy appears to be attributable to the step of aluminium hydroxide adsorption, which is routine in the two-stage assay, but not used in the one-stage assay. The combined implication of these discrepancies, namely that the result of an VIII: C assay depends both on assay method and on reagents, reveals certain limitations in the present system of standardization.

UI	MeSH Term	Description	Entries
D007202	Indicators and Reagents	Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499)	Indicator,Reagent,Reagents,Indicators,Reagents and Indicators
D010949	Plasma	The residual portion of BLOOD that is left after removal of BLOOD CELLS by CENTRIFUGATION without prior BLOOD COAGULATION.	Blood Plasma,Fresh Frozen Plasma,Blood Plasmas,Fresh Frozen Plasmas,Frozen Plasma, Fresh,Frozen Plasmas, Fresh,Plasma, Blood,Plasma, Fresh Frozen,Plasmas,Plasmas, Blood,Plasmas, Fresh Frozen
D012015	Reference Standards	A basis of value established for the measure of quantity, weight, extent or quality, e.g. weight standards, standard solutions, methods, techniques, and procedures used in diagnosis and therapy.	Standard Preparations,Standards, Reference,Preparations, Standard,Standardization,Standards,Preparation, Standard,Reference Standard,Standard Preparation,Standard, Reference
D001780	Blood Coagulation Tests	Laboratory tests for evaluating the individual's clotting mechanism.	Coagulation Tests, Blood,Tests, Blood Coagulation,Blood Coagulation Test,Coagulation Test, Blood,Test, Blood Coagulation
D005169	Factor VIII	Factor VIII of blood coagulation. Antihemophilic factor that is part of the factor VIII/von Willebrand factor complex. Factor VIII is produced in the liver and acts in the intrinsic pathway of blood coagulation. It serves as a cofactor in factor X activation and this action is markedly enhanced by small amounts of thrombin.	Coagulation Factor VIII,Factor VIII Clotting Antigen,Factor VIII Coagulant Antigen,Factor VIII Procoagulant Activity,Thromboplastinogen,Blood Coagulation Factor VIII,F VIII-C,Factor 8,Factor 8 C,Factor Eight,Factor VIIIC,Hyate-C,Hyatt-C,F VIII C,Hyate C,HyateC,Hyatt C,HyattC
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man