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Updated: Aug 2, 2026
Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Familial discrepancy between the one-stage and two-stage factor VIII methods in a subgroup of patients with
E M Duncan1, B M Duncan, L J Tunbridge
1Haemostasis Section, Institute of Medical and Veterinary Science, Adelaide, South Australia.
A higher result for plasma factor VIII:C measured by the one-stage as compared with the two-stage method has been described in some patients with haemophilia A or with von Willebrand's disorder. We used both methods to measure FVIII:C in 95 patients with haemophilia A. The results were equivalent in all 21 patients with severe haemophilia (16 families) and in 45 of the patients with mild or moderate haemophilia (18 families). However, the results were discrepant (FVIII:C by one-stage assay 2-7-fold higher than by two-stage assay) in the other 29 patients with mild or moderate haemophilia (12 other families). For each patient with discrepant FVIII:C results the classification was the same for all other affected members of his family. In some families with haemophilia A the gene defect leads to a discrepancy between the one-stage and two-stage FVIII:C results and may be more widespread than previously recognized.
A higher result for plasma factor VIII:C measured by the one-stage as compared with the two-stage method has been described in some patients with haemophilia A or with von Willebrand's disorder. We used both methods to measure FVIII:C in 95 patients with haemophilia A. The results were equivalent in all 21 patients with severe haemophilia (16 families) and in 45 of the patients with mild or moderate haemophilia (18 families). However, the results were discrepant (FVIII:C by one-stage assay 2-7-fold higher than by two-stage assay) in the other 29 patients with mild or moderate haemophilia (12 other families). For each patient with discrepant FVIII:C results the classification was the same for all other affected members of his family. In some families with haemophilia A the gene defect leads to a discrepancy between the one-stage and two-stage FVIII:C results and may be more widespread than previously recognized.
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