What laboratory value should be monitored for a client prescribed heparin?

A. Red blood cells: While red blood cell counts provide information about oxygen-carrying capacity and anemia, they do not directly reflect the anticoagulant effect of heparin or the risk of bleeding due to its use. Monitoring RBCs is not sufficient for safe heparin therapy. B. International normalized ratio (INR): INR is primarily used to monitor warfarin therapy, not heparin. It measures the extrinsic pathway of coagulation, whereas heparin affects the intrinsic pathway, so INR is not the appropriate laboratory value for heparin monitoring. C. Partial thromboplastin time (PTT): PTT measures the effectiveness of the intrinsic and common coagulation pathways, which are directly affected by heparin. Monitoring PTT helps ensure that the client maintains a therapeutic anticoagulation range and reduces the risk of bleeding or clot formation. D. Hematocrit: Hematocrit reflects the proportion of red blood cells in the blood and can indicate blood loss over time. While important for general assessment, it does not specifically monitor heparin’s anticoagulant effect and is not the primary lab value to guide dosing.