Technochrom® Factor VIII:C is a reagent kit for the photometric determination of coagulation factor VIII activity in plasma and factor VIII concentrates by measuring factor Xa generation with a chromogenic substrate. The kit shows an excellent correlation with one and two stage Factor VIII assays and a linear calibration curve between 0 and 130%. It contains all components, is insensitive to heparin up to 10 IU/ml and is suitable for plasma and concentrates. The Technochrom® Factor VIII:C kit can be used for assaying Factor VIII deficiencies as well as studying Factor VIII substitution.

  • 2 x 2 Substrate FXa-1+ αNAPAP, 10 µmoL / vial F Xa-1, 0.012 µmoL / vial αNAPAP
  • 2 x 2 Reagent A, Phospholipid, albumin
  • 2 x 2 Reagent B, F IXaß, F X, Ca++, albumin, thrombin
  • 1 x 1 Ref. Stand. FVIII 1, ~ 130 % or 1.30 IU FVIII / ml
  • 1 x 1 Ref. Stand. FVIII 2, ~ 70 % or 0.70 IU FVIII / ml
  • 1 x 1 Ref. Stand. FVIII 3, ~ 10 % or 0.1 IU FVIII / ml
  • 1 x 1 Ref. Stand. FVIII 4, < 0.5 % or 0.005 IU FVIII / ml
  • 3 x 30 FVIII dilution buffer, 3.4 g/L Imidazole, 5.85 g/L NaCI, 0.2% Albumin, pH 7.4
  • 2 x 8 FVIII reaction buffer, 6.06 g/L Tris, 3.03 g/L Na2ETDA, 25 g/L NaCI, pH 8.3

MATERIAL REQUIRED (not supplied with the kit)

  • Pipettes – Distilled water
  • For the endpoint method: 20 % acetic acid.
  • Control Plasma Normal and Abnormal:
    Coagulation Control N, 5 x 1 ml, Catalog # 5020040
    Coagulation Control A, 5 x 1 ml, Catalog # 5021055
FVIIIsample + (FIX-PL- Ca++) FVIIIa-FIX-PL-Ca++-complex
Substrate-FXa-1 Substrate-FXa-1 + pNA
Who can benefit from using chromogenic factor VIII assays?
Clinicians or researchers interested in determining FVIII levels in patients with hemophilia A or with elevated factor VIII levels, which may be associated with thrombotic risk. Also, manufacturers interested in determining factor VIII potencies. The chromogenic FVIII activity method has been selected as the reference method by the EP for potency estimation of VIII concentrates, and it is a valuable tool for diagnosis an monitoring of hemophilia and for thrombophilia screening.
What should I do for standards and controls for Factor VIII?
DiaPharma has calibrators, normal and abnormal controls available. Clinicians can also use their own pooled normal plasma; however, it must be calibrated against an international standard to be sure what concentration the plasma has. If the normal plasma does not contain exactly 1 IU/ml ( which corresponds to 100%) factor VIII, the values of the standards must be recalculated in order to obtain a correct factor potency assignment. Reference plasma is available from the National Institute for Biological Standards and Controls (NIBSC). The calibration should be performed by running complete standard curves on two or more independent occasions. Industrial manufacturers, in contrast, use for their standard Mega-2, which is a compilation of factor VIII concentrate.
What are the latest recommendations for measuring potencies of high purity factor VIII concentrates?
  1. A concentrate standard should be used in lieu of plasma standards.
  2. Sample and standard concentrates should be pre-diluted in Factor VIII deficient plasma
  3. All assay buffers should contain 1% (10 mg/ml) of high purity albumin, either bovine or human.
  4. The chromogenic method is the reference method.
What are FVIII inhibitors, and how can I measure them?
FVIII inhibitors appear in about 25% of severe hemophilia A patients. They are most common in patients with inversions, large deletions and nonsense mutations. Inhibitor titer varies 1000-fold; high titer seriously impairs treatment efficacy. Inhibitors can be transient or persistent. and appear irrespective of which FVIII concentrate is selected. High titer patients are treated with high doses of human or porcine concentrate. View the FVIII product pages for kits and assays for FVIII Inhibitor measurements.
What is the function of von Willebrand Factor? Briefly describe von Willebrand disease.
von Willebrand factor (vWf) is a glue-like adhesive protein that is responsible for the adhesion of platelets to damaged vascular endothelium. It also carries and protects factor VIII. von Willebrand disease is a hereditary bleeding disorder caused by moderate-to-severe factor VIII deficiency and low-levels of factor VIII-related antigen (substances necessary for blood clotting). Additionally, there is insufficient von Willebrand factor which also helps blood clot. The von Willebrand factor helps platelets to stick to the blood vessel wall and to each other, which is necessary for normal blood clotting.

Visit the vWF product pages for available kits to measure vWF antigen, activity, and collagen binding.

Protein concentrations in plasma
Component Molecular
Weight kDa
Fibrinogen 330 3000 9
Prothrombin 72 150 2
Factor V 330 20 0.05
Factor VII 50 0.5 0.01
Factor VIII 330 0.1 0.0003
Factor IX 56 5 0.09
Factor X 59 8 0.13
Factor XI 160 5 0.03
Factor XII 80 30 0.4
Factor XIII 320 10 0.03
Protein C 62 4 0.06
Protein S 70 10 (free) 0.14
Protein Z 62 2 0.03
Prekallikrein 86 50 0.6
HMW kininogen 120 70 0.6
Fibronectin 450 300 0.7
Plasminogen 92 200 2
t-PA 60 0.005 0.0001
Urokinase 53 0.004 0.0001
Antithrombin 58 145 2.5
Heparin Cofactor II 66 80 1.2
Plasmin Inhibitor 63 60 1
Protein C Inhibitor 57 4 0.07
α2-Macroglobulin 725 2000 3