Question

an older client is taking warfarin sodium po 2.5 mg twice a day. which laboratory value should the nurse identify as a therapeutic response of the medication?
a aptt of 3 times normal.
b ptt of 20 seconds.
c pt of 4 seconds.
d inr of 2 to 3.

Explanation:

Warfarin is an anticoagulant, and the therapeutic monitoring for warfarin is the International Normalized Ratio (INR). The therapeutic range for INR in patients on warfarin (for most conditions like atrial fibrillation, deep vein thrombosis prophylaxis) is typically 2 to 3.

• Option A: aPTT (activated Partial Thromboplastin Time) is used to monitor heparin therapy, not warfarin, so this is incorrect.
• Option B: PTT (Partial Thromboplastin Time) is also related to heparin monitoring, not warfarin, and 20 seconds is a normal PTT value, so this is incorrect.
• Option C: PT (Prothrombin Time) alone is not sufficient; INR is the standardized measure. A PT of 4 seconds is abnormal but not the therapeutic marker for warfarin, so this is incorrect.
• Option D: INR of 2 to 3 is the therapeutic range for warfarin, so this is correct.

Answer:

D. INR of 2 to 3.