Prothrombin Time (PT/INR)
Protime, INR
Testing Information
Sample Type
Plasma
Test Codes
650720
CPT Code
85610
Testing Area
Core Lab - Coagulation
Test Methodology
Sysmex CA-Series - Photo-Optical Clot Detection
Reference Range
11.0-13.5 secondsCritical Value: >45 seconds
Expected Turnaround Time
Results Available 24 hours from Receipt
Specimen Collection Criteria
Collect one light blue top tube (3.2% sodium citrate). Tube must be filled to line etched on tube or within 10% of the line. Invert tube by gentle inversion six times to ensure liquid anticoagulant is mixed with blood. If using a butterfly collection system to draw the specimen, draw a discard tube in advance of drawing the light blue top.
Rejection Criteria
Clotted specimens, grossly hemolyzed specimens, quantity not sufficient, grossly lipemic specimens, improperly labeled, glass tubes, 3.8% sodium citrate tubes, thawed or partially thawed specimens.
Specimen Validity and Retention
Light Blue Sodium Citrates:Room Temperature (20-25°C): 24 hoursRefrigerated (2-8°C): UnacceptableFrozen (-20°C or greater): UnacceptableSerum Aliquots:Room Temperature (20-25°C): 24 hoursRefrigerated (2-8°C): UnacceptableFrozen (-20°C or greater): 7 daysSpecimens retained for 7 days after testing
Courier Transportation
Transport whole blood specimen at room temperature (20-26°C). Do not refrigerate.Transport plasma aliqots on dry ice, frozen (-20°C or below).
Clinical Utility
The PT/INR test is used to detect factor deficiencies and coagulopathies. It is also used to monitor oral anticoagulant therapy such as warfarin.
