When monitoring a client on warfarin therapy, what laboratory test is vital?

Monitoring a client on warfarin therapy primarily involves measuring the PT (prothrombin time) and the INR (International Normalized Ratio). Warfarin is an anticoagulant medication that works by inhibiting the synthesis of vitamin K-dependent clotting factors, which can lead to an increased risk of bleeding. Therefore, it's crucial to regularly check the PT/INR to ensure that the blood coagulation levels are within the therapeutic range.

The INR standardizes the PT measurement, allowing for consistency across different laboratories. Clinicians use the INR to manage and adjust warfarin dosages to maintain an effective anticoagulation level while minimizing the risk of excessive bleeding or thrombosis.

While other tests such as a complete blood count, liver enzymes, and platelet count may provide supportive information related to the overall health of the patient or potential effects of therapy, they are not specifically targeted for monitoring the anticoagulant effects of warfarin. Therefore, the PT/INR is the vital laboratory test for anyone undergoing warfarin therapy.