Why do we use PT (prothrombin test) to monitor oral anticoagulant therapy (OACT) ??????

[gawsh!]

and why not aPTT??? im *SO* lost! somebody pls help!!! i cant find it anywhere! =S

[sean]

There are several different pathways by which blood clots. If one gets blocked, the blood will still clot by another pathway.

aPTT measures one pathway, but not the path blocked by Coumadin (Warfarin) so people on OACT will often have a normal aPTT.

The PT (or more accurately the INR) measures the path blocked by Coumadin