Which assay is used to titrate factor VIII inhibitors?

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Multiple Choice

Which assay is used to titrate factor VIII inhibitors?

The process of quantifying how strong an antibody to factor VIII is relies on the Bethesda Inhibitor Assay. In this test, patient plasma is mixed with normal plasma and incubated, then the residual factor VIII activity is measured. The amount of inhibitor is reported in Bethesda units, with 1 Bethesda unit defined as the amount of inhibitor that neutralizes 50% of FVIII under standard conditions. This titration tells you how strong the inhibitor is and helps guide therapy and monitoring over time. The mixing study is mainly for detecting the presence of an inhibitor and distinguishing it from a FVIII deficiency, not for measuring the inhibitor's strength. A chromogenic FVIII assay measures FVIII activity itself rather than the inhibitor titer, and PT/INR assesses the extrinsic coagulation pathway, not FVIII inhibitors.

The process of quantifying how strong an antibody to factor VIII is relies on the Bethesda Inhibitor Assay. In this test, patient plasma is mixed with normal plasma and incubated, then the residual factor VIII activity is measured. The amount of inhibitor is reported in Bethesda units, with 1 Bethesda unit defined as the amount of inhibitor that neutralizes 50% of FVIII under standard conditions. This titration tells you how strong the inhibitor is and helps guide therapy and monitoring over time.

The mixing study is mainly for detecting the presence of an inhibitor and distinguishing it from a FVIII deficiency, not for measuring the inhibitor's strength. A chromogenic FVIII assay measures FVIII activity itself rather than the inhibitor titer, and PT/INR assesses the extrinsic coagulation pathway, not FVIII inhibitors.

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