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:

  1. Hoffbrand AV, Pettitt JE (1999). Essential Haematology. Blackwell Scientific Publications, Oxford.