In the setting of heparin resistance due to antithrombin III deficiency, which agent can be used to restore heparin effectiveness?

In the setting of heparin resistance due to antithrombin III deficiency, which agent can be used to restore heparin effectiveness?

• A. Fresh frozen plasma
• B. Vitamin K
• C. Cryoprecipitate
• D. Platelets

Answer: (A)

The key idea is that heparin works by boosting the activity of antithrombin III to inhibit thrombin and factor Xa. When antithrombin III is deficient, heparin can’t exert its anticoagulant effect effectively, causing heparin resistance. Replacing antithrombin III restores heparin’s ability to inhibit those coagulation factors. Fresh frozen plasma provides antithrombin III along with other plasma proteins, so it can reverse this resistance by replenishing ATIII levels. Vitamin K would not help because it changes the synthesis of vitamin K–dependent factors, not ATIII. Cryoprecipitate mainly supplies fibrinogen, factor VIII, and von Willebrand factor, not ATIII. Platelets don’t increase ATIII levels. So, fresh frozen plasma is the appropriate choice to restore heparin effectiveness in ATIII deficiency.

The key idea is that heparin works by boosting the activity of antithrombin III to inhibit thrombin and factor Xa. When antithrombin III is deficient, heparin can’t exert its anticoagulant effect effectively, causing heparin resistance. Replacing antithrombin III restores heparin’s ability to inhibit those coagulation factors. Fresh frozen plasma provides antithrombin III along with other plasma proteins, so it can reverse this resistance by replenishing ATIII levels. Vitamin K would not help because it changes the synthesis of vitamin K–dependent factors, not ATIII. Cryoprecipitate mainly supplies fibrinogen, factor VIII, and von Willebrand factor, not ATIII. Platelets don’t increase ATIII levels. So, fresh frozen plasma is the appropriate choice to restore heparin effectiveness in ATIII deficiency.