A mixing study will remain uncorrected in a patient who has which condition?

A mixing study will remain uncorrected in a patient who has which condition?

• A. hemophilia A
• B. heparin
• C. HIT
• D. hemophilia B

Answer: (B)

Mixing studies distinguish a deficiency from an inhibitor or from an exogenous anticoagulant. When normal plasma is added to patient plasma, a true factor deficiency is corrected because the missing factor from the normal plasma restores hemostasis. But if an inhibitor is present—or if anticoagulant factors like heparin are in the plasma—the clotting time remains prolonged because the interfering agent continues to block coagulation despite the added factors. In this scenario, the mixing study stays uncorrected because active heparin in the patient’s plasma inhibits clotting and isn’t neutralized by simply mixing with normal plasma. Hemophilia A or B would typically correct because the normal plasma supplies the missing factor. While HIT involves heparin exposure, the fundamental reason the study remains prolonged is the presence of heparin itself.

Mixing studies distinguish a deficiency from an inhibitor or from an exogenous anticoagulant. When normal plasma is added to patient plasma, a true factor deficiency is corrected because the missing factor from the normal plasma restores hemostasis. But if an inhibitor is present—or if anticoagulant factors like heparin are in the plasma—the clotting time remains prolonged because the interfering agent continues to block coagulation despite the added factors.

In this scenario, the mixing study stays uncorrected because active heparin in the patient’s plasma inhibits clotting and isn’t neutralized by simply mixing with normal plasma. Hemophilia A or B would typically correct because the normal plasma supplies the missing factor. While HIT involves heparin exposure, the fundamental reason the study remains prolonged is the presence of heparin itself.