Comparison of factor deficient plasmas for measuring Factor VIII and IX

Introduction Factor dosages are part of the diagnostic work up in patients with bleeding tendency (factor (F) VIII and FIX) or in thrombophilia screening (FVIII). The correct diagnosis of FVIII and FIX deficiency and the assessment of severity of the disease are essential for a patient-tailored treatment strategy. Persistently high levels of FVIII are regarded as a thrombophilia risk marker. FVIII can be measured using the one-stage clotting assay, two-stage clotting assay and the chromogenic (amidolytic) assay. The one-stage method suffers from diversity in the reagents and assay conditions used: difference in activated partial thromboplastin time (aPTT) reagents, deficient plasmas, reference plasmas, and instruments.