Clinical Manifestations of DVT
Clinical Manifestations of DVT ( 5 Questions)
A nurse is reviewing the laboratory results of a client who is receiving unfractionated heparin for DVT.
Which of the following values indicates a therapeutic effect of heparin?
Platelet count of 150,000/mm3 is within the normal range of 150,000 to 450,000/mm3. Heparin does not affect platelet count directly, but it can cause heparin-induced thrombocytopenia, a serious complication that reduces platelet count and increases the risk of thrombosis.
Activated partial thromboplastin time (aPTT) of 60 seconds. This value indicates a therapeutic effect of heparin because it is about two times the normal value of 25 to 35 seconds. Heparin produces its major anticoagulant effect by inactivating thrombin and factor Xa through an antithrombin-dependent mechanism. The APTT measures the intrinsic and common pathways of coagulation, which are affected by heparin.
Prothrombin time (PT) of 12 seconds is within the normal range of 11 to 13.5 seconds. Heparin does not affect PT significantly because PT measures the extrinsic and common pathways of coagulation, which are not affected by heparin.
International normalized ratio (INR) of 1.0 is within the normal range of 0.8 to 1.2. Heparin does not affect INR significantly because INR is a standardized measure of PT that reflects the activity of vitamin K-dependent factors, which are not affected by heparin.
The correct answer is choice B. Activated partial thromboplastin time (aPTT) of 60 seconds. This value indicates a therapeutic effect of heparin because it is about two times the normal value of 25 to 35 seconds. Heparin produces its major anticoagulant effect by inactivating thrombin and factor Xa through an antithrombin-dependent mechanism. The APTT measures the intrinsic and common pathways of coagulation, which are affected by heparin.
Choice A is wrong because platelet count of 150,000/mm3 is within the normal range of 150,000 to 450,000/mm3. Heparin does not affect platelet count directly, but it can cause heparin-induced thrombocytopenia, a serious complication that reduces platelet count and increases the risk of thrombosis.
Choice C is wrong because prothrombin time (PT) of 12 seconds is within the normal range of 11 to 13.5 seconds. Heparin does not affect PT significantly because PT measures the extrinsic and common pathways of coagulation, which are not affected by heparin.
Choice D is wrong because international normalized ratio (INR) of 1.0 is within the normal range of 0.8 to 1.2. Heparin does not affect INR significantly because INR is a standardized measure of PT that reflects the activity of vitamin K-dependent factors, which are not affected by heparin.