| Ordering Code | 514 |
|---|---|
| Test Name | Prothrombin Time (PT) |
| Alias | Protime PT INR |
| Preferred Specimen | Whole Blood |
| Preferred Container | Citrate, 3.2% (Lt Blue) |
| Other Specimen/Container | Plasma in Citrate, 3.2% (Lt Blue) |
| Optimum Volume | Whole Blood: Entire tube Plasma: 1.0 mL |
| Collection Instructions | Draw full tube Mix tube well. |
| Handling Instructions | Do NOT chill whole blood - results may be affected. If sending plasma: double centrifuge to produce platelet-poor plasma, avoid the WBC/platelet buffy layer, separate and freeze at -20 deg C immediately. Do NOT thaw once specimen is frozen. |
| Transport Requirements | On Oahu: Ambient if Whole Blood and testing is done within 24 hours Airline: Frozen (Plasma) Note: Send Frozen Plasma if testing will be done >24 hours from collection |
| Specimen Stability | Ambient: 24 Hours Refrigerated: Not Stable Frozen: 2 Weeks Plasma |
| Rejection Criteria | Clotted, Contaminated, Hemolyzed, Overfilled tube, Specimen older than stability limits, Underfilled tube, Collected in the wrong anticoagulant, Mislabeled |
| Avail. Stat | YES |
| Analytic Time | 1 Day |
| Methodology | Clot Detection |
Reference range(s)
The reference ranges listed below are valid on this date of May 18, 2025.
| Component | Age | Male Norm | Male Critical Low | Male Critical High | Female Norm | Female Critical High | Female Critical Low | Units | Add'l info |
|---|---|---|---|---|---|---|---|---|---|
| Prothrombin Time (PT) | ALL | 10.2-12.9 | 10.2-12.9 | secs | |||||
| INR | ALL | >= 4.5 | >= 4.5 | Moderate-intensity... Note1 |
Note1:
Moderate-intensity Warfarin therapy 2.0-3.0Higher-intensity Warfarin therapy 2.5-3.5
.