Factor VIII (synonym: antihemophilic globulin A) is one of the coagulation factors.
Defects affecting factor VIII are usually inherited in an X-linked recessive manner. Men are affected with a probability of 1:6,000 and are then referred to as hemophilia A (hemophilia). There is a reduced synthesis of the clotting factor or abnormal proteins are produced.
An increase in factor VIII occurs with increasing age, and levels are also higher in women than in men. Elevations of > 150% carry a multiple increased risk of thrombosis. Among other factors, a genetic influence is thought to be involved.
The procedure
Material needed
- At least one complete tube of citrated blood (for multiple factors, 200 µl of plasma per factor).
Preparation of the patient
- Not necessary
Disruptive factors
- The analysis should be done within a few hours (otherwise freeze).
Normal value
| Normal value in % | 70-200 |
Indications
- Suspicion of hemophilia A
- Suspicion of thrombophilia (increased tendency to clot).
Interpretation
Interpretation of increased values
- Thrombophilia (elevation of > 150%).
Interpretation of decreased values
- Hemophilia A
Further notes
- As a rule, the standard clotting parameters Quick (normal), PTT (pathological), PTZ (normal) are determined first when a deficiency of clotting factors is suspected
- After thrombosis, factor VIII should be determined two months after diagnosis and one month after stopping anticoagulation!