Home
HelpTest Code PTINR Prothrombin Time
Additional Codes
| Epic Ordering Code | LAB320 |
| NBS code | LBC00843 |
| Service code | 12403 |
Specimen Requirements
Submit the following:
| Preferred: |
| Light Blue Top |
|
|
Processing Requirements
Submit only one of the following specimens:
Specimen Type: Whole Blood
Container/Tube: Light Blue Top (3.2% Sodium Citrate)
Volume: 2.7 mL Whole Blood (Tube must be full)
Collection Instructions: Send whole blood specimen to laboratory immediately.
Specimen Type: Platelet Poor Plasma
Container/Tube: Light Blue Top (3.2% Sodium Citrate)
Submission Container/Tube: Plastic Vial
Minimum Volume: 1.0 mL Plasma
Collection Instructions:
1. Light Blue top tube must be properly filled with whole blood.
2. Whole blood specimen should be double centrifuged and plasma separated from cells within 4 hrs of collection
3. Freeze the plasma in well-closed plastic tube immediately.
Specimen Stability
| Specimen Type | Whole Blood | Plasma |
|---|---|---|
| Ambient | 24 hours | 24 hours |
| Refrigerate | Unacceptable | Unacceptable |
| Frozen | Not available | 14 days |
Specimen Condition
| Gross Haemolysis | Reject |
|---|---|
| Icterus | OK |
| Lipaemia | OK |
| Others: Clotted or insufficient specimen | Reject |
Methodology
Photo-optical Clot Detection
Days and Times Performed
24 hrs, TAT 1 day
Reference Interval
| Adults | 9.4 – 11.2 seconds |
|---|---|
| Venous Thromboembolism | 2.0 – 3.0 INR |
| Mechanical Heart Valves | 2.5 – 3.5 INR |
Critical values: Refer to Critical Values Table
Testing Laboratory
National University Hospital
Haematology, 67725320
Useful For
Monitoring of anticoagulation therapy, e.g. Warfarin.
Screening test for clotting factor deficiency, e.g. Factor VII.
PTINR will be prolonged in disseminated intravascular coagulation, liver disease and vitamin K deficiency.
Update
Last updated 22/06/2026
Alias
INR
Protime
PT
LOINC Code Information
| PT | 5902-2 |
|---|---|
| INR | 6301-6 |