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HelpTest Code PTIM Protime-INR, LAB320
Performing Laboratory
St. Luke's Hospital Cedar Rapids
Specimen Requirements
Container/Tube:
Preferred: Full Blue-top (sodium citrate)
tube (1.8mL)-Hemolyzed or short draw specimen is not
acceptable.
Specimen Volume: 0.5 mL sodium citrate
plasma
Stability: Uncentrifuged or centrifuged in an unopened tube kept at 18-24°C must be tested within 24 hours from the time of specimen collection. If testing is not completed within 24 hours, plasma should be removed from the cells and frozen at -20°C for up to two weeks.
NOTE: Patients with a hematocrit of >55% must be recollected using an altered amount of sodium citrate.
Reference Values
|
|
Protime (seconds) |
INR |
|||
|
Age |
Low |
High |
Low |
High |
Critical |
|
0-1 day |
10.0 |
15.2 |
0.8 |
1.3 |
≥1.6 |
|
2-5 days |
9.4 | 14.6 |
0.8 |
1.2 |
≥1.6 |
|
6-29 days |
9.3 | 13.6 |
0.8 |
1.1 |
≥1.6 |
|
1-3 months |
9.5 | 13.5 |
0.8 |
1.1 |
≥1.6 |
|
4-11 months |
10.6 | 13.2 |
0.9 |
1.1 |
≥1.6 |
|
1 – 5 years |
10.3 |
10.8 | 0.8 | 0.9 |
≥1.6 |
|
6 – 10 years |
9.9 | 11.5 | 0.8 | 1.0 |
≥1.6 |
|
11 – 16 years |
10.0 | 11.4 |
0.8 |
1.0 |
≥1.6 |
|
>16 year |
10.7 | 13.3 |
0.9 |
1.1 |
≥5.0 |
Day(s) Test Set Up
Monday through Sunday
Useful For
The prothrombin time (PT) and calculated international normalized ratio (INR) is a useful screening procedure for deficiencies in factors II, V, VII, and X. This test may be used to follow the course of anticoagulant therapy in patients receiving Coumadin drugs.
Methodology
Clot Based Assay
Test Classification and CPT Coding
85610
Report Available
STAT within 1 hour upon receipt
Routine within 2 hours upon receipt