Autoanti-VIII inhibitor
Definition:
Autoantibodies that specifically inhibit factor VIII and are time and temperature dependent (type II kinetics)
Incidence:
Seen in the following patients:
Pregnant patients
Postpartum patients
Autoimmune disorders
Lymphoproliferative disorders
Elderly patient
Detection:
aPTT that is initially prolonged and initially corrected when mixing studies are performed but becomes prolonged when the incubation time is extended to 2 hours at 37oC