Which laboratory test is critical for monitoring during heparin infusion?

The critical laboratory test for monitoring during heparin infusion is the Activated Partial Thromboplastin Time (APTT). Heparin is an anticoagulant that works primarily by inhibiting thrombin and factor Xa in the coagulation cascade. The APTT specifically assesses the intrinsic and common pathways of coagulation, which are influenced by heparin's action.

Monitoring APTT during heparin therapy allows healthcare providers to determine the effectiveness of the anticoagulation and to adjust the heparin dose accordingly to maintain the desired therapeutic range. Typically, the therapeutic goal for APTT during heparin infusion is to achieve levels that are 1.5 to 2.5 times the normal baseline value.

While PT, INR, and CBC are important tests in various contexts, they do not accurately reflect the anticoagulant effect of heparin. PT and INR are primarily used for warfarin therapy monitoring, which affects the extrinsic pathway of coagulation. A CBC may be useful for monitoring platelet counts to watch for potential heparin-induced thrombocytopenia, but it does not provide direct information about the anticoagulant effect of heparin. Therefore, APTT is the key test for