investigations
Last reviewed 01/2018
The following results occur in Haemophilia A and Haemophilia B:
- activated partial thromboplastin time (APTT); prolongation depends on the severity of the factor deficiency. Prolonged APTT plus prolonged bleeding suggests von Willebrand's disease
- factor VIII clotting assay - low levels in Haemophilia A
- factor IX clotting assay - low levels in Haemophilia B
- note that in severe cases of Haemophilia B whole blood coagulation time is increased (1)
Other investigations:
- normal tests in Haemophilia A and Haemophilia B include:
- prothrombin time (PT)
- bleeding time
- normal von Willebrand factor
- Other
investigations include:
- DNA probes - genes for Factor VIII and Factor IX have been cloned and characterised.
- pedigree analysis - may diagnose female carriers with certainty in some situations - for example all daughters of a known haemophiliac male are obligate carriers
Reference:
- Hoffbrand AV, Pettitt JE (1999). Essential Haematology. Blackwell Scientific Publications, Oxford.
activated partial thromboplastin time
von Willebrand's disease (comparison with the features of Haemophilia A and Haemophilia B)