What is the FVIII:C inhibitor?

Get ready for the CAMLPR Hematology Test. Use our quizzes, flashcards, and detailed explanations to enhance your understanding. Prepare confidently for your exam!

Multiple Choice

What is the FVIII:C inhibitor?

FVIII:C inhibitor is an autoantibody that neutralizes factor VIII activity, causing acquired hemophilia A. The key clue is a prolonged aPTT that does not correct with a mixing study (patient plasma mixed with normal plasma) and that often becomes even longer after incubation, reflecting time‑dependent inhibition of FVIII. This pattern distinguishes it from inherited FVIII deficiency, where mixing usually corrects because there’s no inhibitor present. It also sets it apart from von Willebrand disease, which is a defect or deficiency of von Willebrand factor rather than antibodies against FVIII, and from primary platelet defects, which affect bleeding in a different way and don’t produce the same inhibitor‑related mixing study results. A Bethesda assay can quantify the inhibitor titer.

FVIII:C inhibitor is an autoantibody that neutralizes factor VIII activity, causing acquired hemophilia A. The key clue is a prolonged aPTT that does not correct with a mixing study (patient plasma mixed with normal plasma) and that often becomes even longer after incubation, reflecting time‑dependent inhibition of FVIII. This pattern distinguishes it from inherited FVIII deficiency, where mixing usually corrects because there’s no inhibitor present. It also sets it apart from von Willebrand disease, which is a defect or deficiency of von Willebrand factor rather than antibodies against FVIII, and from primary platelet defects, which affect bleeding in a different way and don’t produce the same inhibitor‑related mixing study results. A Bethesda assay can quantify the inhibitor titer.

More practice questions