California Phlebotomy Certification Practice Exam

Which test results are affected by the medication warfarin?

1. Complete blood count

2. PT / INR

3. Lipid panel

4. Glucose levels

The correct answer is: PT / INR

The test results that are affected by the medication warfarin are the PT (Prothrombin Time) and INR (International Normalized Ratio). Warfarin is an anticoagulant medication commonly prescribed to prevent blood clots. It works by inhibiting the synthesis of vitamin K-dependent clotting factors, which are crucial for normal blood coagulation. Since PT measures the time it takes for blood to clot and INR is used to monitor patients on warfarin, any changes in warfarin dosage or patient response to the medication will directly influence these test results. Health care providers rely on PT/INR values to ensure that a patient is within the therapeutic range, which helps balance the risk of clotting against the risk of excessive bleeding. This makes PT and INR critical markers for monitoring patients who are receiving warfarin therapy. In contrast, other tests such as the complete blood count, lipid panel, and glucose levels are not specifically influenced by warfarin. For example, a complete blood count primarily assesses overall health and detects a variety of disorders such as anemia or infection, while a lipid panel measures levels of fats in the blood and glucose levels indicate blood sugar control. These tests remain unaffected by the anticoagulant activity of warfar