A prolonged aPTT is corrected with factor VIII-deficient plasma but not with factor IX-deficient plasma.What factor is deficient?

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Quizplus · Accepted Answer

The fact that the prolonged aPTT is corrected with factor VIII-deficient plasma indicates that factor VIII is deficient, as this correction suggests that the patient's plasma lacks the ability to activate factor X via the intrinsic pathway. The lack of correction with factor IX-deficient plasma rules out a deficiency in factor IX, and the lack of correction with factor V or XIII-deficient plasma suggests that these factors are not involved in the coagulation abnormality being observed. The lack of correction with factor X-deficient plasma is also expected, as this factor is downstream in the clotting cascade, and its activation is dependent on the prior activation of factors VIII and IX.

A Prolonged APTT Is Corrected with Factor VIII-Deficient Plasma but Not