Partial Thromboplastin Time, Activated
Test code
CPT code(s)*
Test resources
Details
Methodology
Photo-Optical Clot Detection
Alternative name(s)
APTT,PTT
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 | 0.3 mL |
| Collection instructions | Unopened light blue-top tube: Correct ratio of blood to citrate is critical. Do not overfill or underfill collection tube. Mix by inversion 4 times. For non-heparinized patients, maintain specimen at room temperature. Do not uncap. Stable 24 hours at room temperature. Platelet-poor plasma: Centrifuge light blue-top tube 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcl). Freeze immediately and ship on dry ice. Whole blood: The tubes should be at 100% +/- 10% fill volume in order to obtain the correct ratio. |
| Transport container | Select a service area to view this section. |
| Transport temperature | Select a service area to view this section. |
| Specimen stability | Unopened light blue-top tube Room temperature: 24 hours Refrigerated: Unacceptable Frozen: Unacceptable Separated platelet-poor plasma Room temperature: Unacceptable Refrigerated: Unacceptable Frozen: 14 days |
| Reject criteria | Gross hemolysis • Grossly lipemic • Improper blood to citrate ratio • Clotted • High hematocrits • Thawed plasma received room temperature or refrigerated |
Reference Range(s)
| ≤6 months | Not established |
| >6 months | 23-32 sec |
Flagging not provided. Pediatric reference intervals have not been established. Based on published literature, the adult reference interval (23-32 seconds) is generally applicable down to approximately 6 months of age with younger patients having a slightly higher upper limit by several seconds.
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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