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Prothrombin Time and Activated Thromboplastin Time Panel
Test CodePT(LOW ISI) AND PTT
Alias/See Also
Prothrombin Time
Activated Partial Thromboplastin Time
Hematology
Activated Partial Thromboplastin Time
Hematology
Includes
Prothrombin Time
INR
Activated Thromboplastin Time
INR
Activated Thromboplastin Time
Preferred Specimen
Light Blue Top Tube – 3.2% sodium citrate
Transport Temperature
Room temp. Do not place directly on ice.
Specimen Stability
Whole blood, unopened tube, centrifuged or uncentrifuged
Non-heparinized patients
Room temperature: 4 hours
Patients for VWF or VIII analysis
Room temperature: 4 hours. Do not refrigerate or freeze.
Patients on unfractionated heparin
Centrifuge within 1hr of collection
Room temperature: 4 hours
Plasma aliquot
Room temperature: 4 hours
Frozen (-20°C): 2 weeks
Frozen (-70°C): 12 months
Stability times listed are based on combined requirements for each test within the panel. Refrigeration not recommended so as to avoid cold activation of Factor VII for PT
Non-heparinized patients
Room temperature: 4 hours
Patients for VWF or VIII analysis
Room temperature: 4 hours. Do not refrigerate or freeze.
Patients on unfractionated heparin
Centrifuge within 1hr of collection
Room temperature: 4 hours
Plasma aliquot
Room temperature: 4 hours
Frozen (-20°C): 2 weeks
Frozen (-70°C): 12 months
Stability times listed are based on combined requirements for each test within the panel. Refrigeration not recommended so as to avoid cold activation of Factor VII for PT
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Under drawn or overdrawn, clotted and hemolyzed specimens are not acceptable for testing. Patient's receiving anticoagulant therapy may give spurious results.
Methodology
Photo-optical endpoint
Setup Schedule
Daily
Report Available
TAT 1 day
Limitations
Monitor warfarin patients based on the INR value only!
INR therapeutic range for patients on oral anticoagulant therapy is 2.0-3.5.
For patients who are not receiving anticoagulant therapy, the INR of 1.1 or lower is considered normal.
INR therapeutic range for patients on oral anticoagulant therapy is 2.0-3.5.
For patients who are not receiving anticoagulant therapy, the INR of 1.1 or lower is considered normal.
Reference Range
| Test | Reference range | Units |
| PT | 9.8 - 13.3 | Sec |
| INR | ≤1.1 | |
| PTT | 27.9 - 37.0 | Sec |
| Heparinized PTT | 55 - 94 (Therapeutic) | Sec |
Comments:
- For normal patient who are not on anticoagulation, the INR of 1.1 or lower is considered normal.
- Therapeutic range for patients on anticoagulant should be between 2.0-3.5
Performing Laboratory
Test performed in BACL Hematology Labs
Contact West Roxbury: Nolan Raymond 857-203-5980
Alternate contact Joseph A. Manzone JP 857-364-5092
Alternate contact Diane Robert Brockton 774-826-2294
Alternate contact Bhumikaben Patel Bedford 781-687-2976
Last Updated: May 19, 2025
