Prothrombin Time with International Normalized Ratio (INR)
- Pro Time
- Protime, PT/INR
- PT/International normalized ratio
UFHPL Epic order code: LAB320
UFHPL - Core Laboratory Recommendations for Anticoagulant Therapy
Although the prothrombin time (PT) and activated thromboplastin time (aPTT) are both affected by vitamin K antagonists (Coumadin) and by heparin, the PT/INR is the recommended first-line assessment of Coumadin therapy.
As an alternative to aPTT measurements for unfractionated heparin, a direct heparin assay can be performed. Heparin is measured as anti-Xa units. Indeed, this is the recommended modality of assessing low molecular weight heparin therapy, since the aPTT is a poor indicator of the response to LMW heparin.
There is increasing use of direct thrombin inhibitors, such as Argatroban. We recommend monitoring the latter with the aPTT using a prolongation of approximately 1.5 to 2.5 times the baseline.
Container/Tube: Light blue (3.2 percent sodium citrate)
Sample Volume: 2 mL of platelet-poor plasma (0.5 mL minimum)
- Ambient: 24 hours
- Frozen: 1 month
- Clotted or hemolyzed samples
- EDTA plasma
Electromagnetic endpoint detection
Within 24 hours
Monday - Friday