EVALUATION OF A CHROMOGENIC FACTOR VIII ASSAY ON THE SYSMEX CS 2100I INSTRUMENT

Abstract

Background: The one-stage factor VIII (FVIII) assay is the most widely used assay for the quantification of FVIII. Several disadvantages of the one-stage assay have been described. The two-stage- and chromogenic FVIII assays purportedly overcame these disadvantages. The chromogenic method is easier to automate and the reagents are readily available. In this evaluation we evaluated the chromogenic FVIII assay on the Sysmex CS 2100i instrument. Methods: We compared the FVIII levels of healthy individuals and haemophilia A patients, as determined by the one-stage and chromogenic FVIII assays, respectively. Results: FVIII levels differed significantly between assays. The lower FVIII detection limit of both assays did not allow the quantification of FVIII for the haemophilia A patients. The addition of heparin led to a decrease in FVIII levels detected by the one-stage FVIII assay, but did not affect the chromogenic assay results. Conclusion: The chromogenic FVIII assay can be introduced into the diagnostic laboratory as part of haemophilia A diagnosis and monitoring. However, the one-stage FVIII assay is still recommended as the first-line screening test as it had a lower FVIII detection limit and was more cost effective.