A patient has been diagnosed with a coagulopathy and has been given Coumadin as a mode of treatment. What screening test(s) should be performed to monitor this treatment, and what effect will this therapy have on the coagulation pathway?

a. APTT; initial decrease in the vitamin K-dependent factors of the intrinsic pathway
b. PT-INR; initial decrease in the vitamin K-dependent factors of the extrinsic pathway
c. PT-INR and APTT; initial decrease in the vitamin K-dependent factors of all pathways
d. PT-INR; initial decrease in all vitamin K-dependent serine proteases

Correct Answer: D