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COMPARISONS OF ONE‐STAGE AND TWO‐STAGE ASSAYS OF FACTOR VIII:C
Author(s) -
Barrowcliffe Trevor W.
Publication year - 1984
Publication title -
scandinavian journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 84
eISSN - 1600-0609
pISSN - 0036-553X
DOI - 10.1111/j.1600-0609.1984.tb02766.x
Subject(s) - stage (stratigraphy) , dilution , chromatography , chemistry , reagent , potency , clotting factor , biology , biochemistry , medicine , in vitro , organic chemistry , thermodynamics , paleontology , physics
Comparisons of one‐stage and two‐stage methods are made in terms of technical aspects, precision and potency estimates. Because of the different dilution ranges and reagents, there is a higher concentration of clotting factors and total protein in the one‐stage essays, and a higher ratio of VIII R:Ag/VIII:C. The one‐stage assay is technically simpler and easier to automate, but the two‐stage method is probably more sensitive. In international collaborative studies, the two‐stage method has been generally more precise, but current differences in precision between the methods are small. Discrepancies between the methods occur in assays of concentrates against plasma standards, sometimes also against concentrate standards, and in assessment of in vivo recovery. The adsorption step used in the two‐stage method is a major cause of the discrepancy is assays of concentrates against plasma. Other possible causes of discrepancies between the methods in assays of concentrates are: pre‐dilution in buffer or haemophilic plasma; thrombin activation; the influence of VIII R:Ag on VIII:C activity; non‐specific contaminants such as lipids.