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| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Partial Thromboplastin Time, Activated
Test Code763
CPT Codes
85730
Preferred Specimen
1 mL platelet-poor plasma collected in a 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.3 mL plasma • 3 mL whole blood
Other Acceptable Specimens
5 mL whole blood collected in: 3.2% sodium citrate (light blue-top) tube, proper blood to anticoagulant ratio is required
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.
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 Temperature
Plasma: Frozen
Whole blood: Room temperature
Whole blood: Room temperature
Specimen Stability
Plasma
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 14 days
Whole blood
Room temperature: 24 hours
Refrigerated: Unacceptable
Frozen: Unacceptable
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 14 days
Whole blood
Room temperature: 24 hours
Refrigerated: Unacceptable
Frozen: Unacceptable
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Gross lipemia • Improper blood to citrate ratio • Clotted • High hematocrits • Thawed plasma received room temperature or refrigerated
Methodology
Photo-Optical Clot Detection
Setup Schedule
Set up: Mon-Fri; Report available: 2-4 days
Limitations
Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: prolonged; Heparin (UFH or LMWH): prolonged; Dabigatran or Argatroban (Thrombin Inhibitors): prolonged; Rivaroxaban or Apixaban (Factor Xa Inhibitors): prolonged.
Reference Range
| ≤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.
Clinical Significance
The aPTT is a screening test that will detect deficiencies or inhibitors to the intrinsic (Factors VIII, IX, XI and XII) and common (Factors II, V, X and fibrinogen) pathway coagulation factors.
