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PT/INR (PROTHROMBIN TIME/INTERNATIONAL NORMALIZED RATIO)
MessageThe Reference range for PT was adjusted on 2/4/2020 when a new lot of PT/INR reagents was placed into use.
Test Code
LAB320
CPT Codes
85610
Preferred Specimen
One 3 mL blue top tube
Pediatric: One 1.8 mL pediatric blue top tube
Pediatric: One 1.8 mL pediatric blue top tube
Minimum Volume
I mL Plasma
Instructions
PT/INR only: Whole blood, unopened sampels are stable at room temperature for 24 hours.
Samples with additional testing ordered must be centrifuged at 3000 rpm for 10 minutes or using a high-speed centrifuge. Platelet poor plasma should be separated into 1 ml aliquots. Samples should be frozen within one hour (best practice), however samples stable for 4 hours. Samples must remain frozen during transport. Any samples that are received thawed are not suitable for testing.
Tube must be filled to etched line to perform testing.
Samples with additional testing ordered must be centrifuged at 3000 rpm for 10 minutes or using a high-speed centrifuge. Platelet poor plasma should be separated into 1 ml aliquots. Samples should be frozen within one hour (best practice), however samples stable for 4 hours. Samples must remain frozen during transport. Any samples that are received thawed are not suitable for testing.
Tube must be filled to etched line to perform testing.
Transport Temperature
Ambient: 24 hours- PT/INR- Whole Blood
Frozen (-70C)- Plasma
Frozen (-70C)- Plasma
Specimen Stability
Ambient: 24 hours if cap has not been removed or punctured for PT/INR only
Frozen: 6 months (-70C)
Frozen: 6 months (-70C)
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Clotted specimen, underfilled tube, or gross hemolysis
Methodology
Optical density on ACL TOP using HemosIL RecombiPlasTin 2G reagent
Setup Schedule
Sunday-Saturday
Reference Range
| Age | PT | INR |
| < 30 days old | 9.4-14.3 sec | 0.80-1.30 |
| Adult ( > 1 month old) | 9.8-14.4 sec | 0.80-1.20 |
| Targets | PT | INR |
| Conventional Anticoagulation | NA | 2.00-3.00 |
| Intensive Therapy | NA | 2.50-3.50 |
Automatically Called Results
INR >5.0
PT: Not applicable
No Result: No result was obtained because clotting was not detected during testing. Please re-order the test and draw a new specimen if clinically indicated.
Clinical Significance
Coumadin therapy INR range for Conventional Anticoagulation is 2.0 to 3.0 and for Intensive Anticoagulation 2.5 to 3.5.
Performing Laboratory
West Virginia University Hospital, Inc.
Berkeley Medical Center
Braxton County Memorial Hospital
Camden Clark Medical Center
Fairmont Medical Center
Jackson General Hospital
Jefferson Medical Center
Potomac Valley Hospital
Reynolds Memorial Hospital
Summersville Regional Medical Center
St Joseph's Hospital
United Hospital Center
Wetzel County Hospital
