Prothrombin Time (PT and INR)
Test Code
PT2
Description
Screening test for abnormalities of coagulation factors that are involved in the extrinsic pathway. Also used to monitor effects of Warfarin therapy and to study patients with hereditary and acquired clotting disorders.
Collect
Blue top tube.
Pediatric Collection
Minimum volume: 0.5 mL
Unacceptable Conditions
Sample will be rejected if Blue top tube under-filled.
Clotted and hemolyzed specimens will also be rejected.
Storage Transport Temp
Offsite: Frozen. Send plasma Priority Overnight via FedEx and in a well insulated container on dry ice.
Stability
Stability after cell separation:
24 hours at RT (15-25°C ),
refrigerated unacceptable,
2 weeks frozen at ≤ -20°C
1 year frozen at ≤ - 70°C
Notes
Make sure Blue top tube is filled properly to assure proper ratio of anticoagulant to whole blood.
Performed
Mon-Fri
Methodology
Chromogenic
Turnaround Time
4 hour routine, 1 hour STAT
Department
Core Lab
Synonyms
Protime; INR; Prothrombin Time; PT
Study Offerings
Not offered
Reference Interval
| Unit = Seconds | Range | Age Group |
|
Protime [PT] |
9.5-12.1 |
All |
| INR | 0.8-1.2 | Normal patient 0.9-1.1 |
| INR | 2.0-3.0 | Treatment/venous thrombosis |
| INR | 2.0-3.0 | Pulmonary embolis |
| INR | 2.0-3.0 | Prophylaxis/venous thrombosis |
| INR | 2.0-3.0 | Systemic embolization |
| INR | 2.5-3.5 | High risk patients with heart valves |
CPT Code
85610
New York Approved
FDA Approved or Cleared
FDA
Approved or Cleared