Discrepancies among several assays results can be observed within the laboratory monitoring of FVIII and FIX replacement therapy, this is especially true for the extended half‐life products. This guideline has evaluated available published data and advices on the assays of choice for laboratory measurement of replacement therapy in Haemophilia A and B without inhibitors. Each haemophilia centre should be able to provide appropriate laboratory assays for FVIII and FIX products locally available.. Assay discrepancies are often observed for the extended half‐life FVIII and FIX products, thus assays of these products may need to be verified with the specific clotting factor concentrates being used.
Reference:
Haemophilia. 2019 Dec 17