Prothrombin Time with INR
Test code
CPT code(s)*
Test resources
Test FAQ
Details
Methodology
Photo-Optical Clot Detection
Alternative name(s)
PT
Specimen requirements | |
|---|---|
| Patient preparation | None Specified |
| Preferred specimen(s) | Select a service area to view this section. |
| Alternative specimen(s) | Select a service area to view this section. |
| Minimum volume | Select a service area to view this section. |
| Collection instructions | A completely filled tube is necessary because the correct ratio of blood to citrate is critical (9:1). Mix by gentle inversion 3-4 times. Do not uncap. |
| Transport container | Select a service area to view this section. |
| Transport temperature | Select a service area to view this section. |
| Specimen stability | Select a service area to view this section. |
| Reject criteria | Gross hemolysis • Grossly lipemic • Improper blood to citrate ratio • High hematocrit • Improper blood collection |
Reference Range(s)
INR
| ≤3 months | Not established |
| >3 months | |
| Reference range | 0.9-1.1 |
| Moderate-intensity Warfarin therapy | 2.0-3.0 |
| Higher-intensity Warfarin therapy | 3.0-4.0 |
PT
| ≤3 months | Not established |
| >3 months | 9.0-11.5 sec |
Flagging not provided. Pediatric reference intervals have not been established. Based on published literature, the adult reference interval (9.0-11.5 seconds) is generally applicable down to approximately 3 months of age with younger patients having a slightly higher upper limit by several seconds. Warfarin Therapeutic INR Range: 2.0 - 3.0
Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.
*The CPT codes provided are based on AMA guidance and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.
This material contains content from LOINC® (http://loinc.org). The LOINC Table, LOINC Table Core are copyright © 1995-2019, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license.
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