Prothrombin Time
Order Code: PT
Order Form: Laboratory Requisition
Specimen:
Plasma
Collection Medium:
Light Blue top tube 1.8 mL (Na Citrate)
Minimum:
Full draw; 1.8 mL light blue top (mix well). Tube must be at least 90% full.
Turn Around Time:
2 hours (upon receipt in laboratory)
Reference Range:
9-12 seconds INR Critical Reference Value: greater than 3.9
Comments:
The INR corresponding to the PT is reported to assist in the monitoring of oral anticoagulants. Must be drawn swiftly with a clean venipuncture (no hematoma). Time drawn must be indicated on requisition. Obtain special tube from lab if hematocrit is over 55%. Sample should be kept at room temperature, unopened to be delivered to lab within 24 hours. Prothrombin Time may be performed on the same collection tube as Activated Partial Thromboplastin time (aPTT) and Fibrinogen. Please print, complete and submit the Advance Beneficiary Notice (ABN) along with the Laboratory Requisition before shipping the specimen.
Methodology:
Optical clot detection.
Sample Processing:
Centrifuge within two hours of draw time.
Aliquot serum/plasma into plastic container and cap (glass is not acceptable).
Centrifuge a second time at 3500 RPM for 10 minutes and aliquot into a new, labeled plastic tube.
Sample Storage:
Freeze specimen immediately.
Transport Instructions:
Place specimen into zip-lock type bag, seal bag.
Place requisition into outside pocket of bag.
Place dry ice on top of specimen in styrofoam container.
CPT Code:
85610
 
See also:
Activated Partial Thromboplastin Time (aPTT), Plasma
 
See Additional Information:
Hematology Critical Lab Values
International Normalized Ratio (INR)
Phlebotomy Tubes and Order of Draw