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HelpTest Code PT Protime
Aliases
PT/INR
Prothrombin Time
Useful For
The prothrombin time (PT) is a basic coagulation screening test for the assessment of congenital and acquired deficiencies of the extrinsic and common pathways (factors I,II,V,VII, X). The PT is also used to monitor warfarin therapy, Vitamin K deficiency disorders, liver failure, fibrinolysis and DIC. Because of the variations in the PT results with different thromboplastins and instruments, it is recommended that the PT results be converted to an INR.
Patient Preparation
No special patient preparation required
Special Collection Instructions
Properly filled 9:1 ratio (blood to anticoagulant); 3.2% NaCitrate tube
Collection Method
Venous Draw; properly filled 9:1 ratio (blood to anticoagulant)
Minimum Volume
0.5 ml of plasma from a properly filled 1.8 mL or 2.7 mL NaCitrate (light blue) tube
Container
Light Blue Sodium Citrate
Preferred Specimen
2.7mL Lt. Blue (3.2% NaCitrate)
Acceptable Specimens
1.8 mL Lt. Blue (3.2% NaCitrate) tube
Reference or Target Ranges
| Normal: | |
|---|---|
| UH | 9.4 - 12.5 seconds |
| WH | 12.5 – 14.2 seconds |
| Normal INR UH |
0.8 – 1.1 |
| Normal INR WCH |
0.9 – 1.1 |
Reportable Units
PT – seconds
Critical Value
| INR | >4 |
Reasons for Rejection
| Hemolysis Threshold | N/A |
| Icterus Threshold | N/A |
| Lipemia Threshold | N/A |
| Interfering Subtances/Other | Short draws, over draws, clotted, improperly labeled |
Specimen Stability
| Ambient | Plasma – 4 hours |
| Clinics only – 24 hours whole blood | |
| Refrigerated (4°C to 8°C) | N/A |
| Frozen(-70°C to -20°C) | 2 Weeks@ -20°C; 1 year @ -70°C |
Performance Information
| Days and Time Performed | 24/7 |
| Expected Turn Around Time | Routine: within 4 hours of arrival to lab Stat:within 1 hour of arrival to lab |
| Stat Availability | Yes |
| Performing Bench | Coagulation |
| Methodology/Method Description |
UH: Werfen ACL TOPS; Photo-optical clot-detection system |
CPT Codes
85610