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INR, Prothrombin Time (PT)

Mnemonic:    [PT]
Name:    INR, Prothrombin Time (PT)
Specimen:    2 mL plasma from a FULL sodium citrate Blue top tube. Allow tube to fill to proper capacity. Mix immediately by gentle inversion 4 times. Sample is stable for 24 hours at room temperature if cap is not removed.

Most coagulation tests (blue top tubes) must be centrifuged within one hour of collection. The prothrombin time/INR is the exception. If there are any other coagulation tests, the room temperature sample must be at the CMMC hematology lab within one hour of collection. If the unspun sample cannot be delivered to the lab in that time period, the patient should be sent to the CMMC Outpatient Phlebotomy area for specimen collection.

Once the tube has been uncapped the sample is only stable for 4 hours.
Reference Range:    w/o Warfarin 0.86 - 1.13INR
Critical Range:    = 5.0 INR
  Method:    Mechanical Clot Detection
Note:    Results reported as an INR (International Normalized Ratio).
Processing Info:    The sample must be kept at room temperature prior to centrifugation. Any samples received separated must have been processed in a CAP approved calibrated and documented centrifuge to provide platelet poor plasma.