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Partial Thromboplastin Time, Activated
Test Code10149
CPT Codes
85730<br>Limited Access Code
Preferred Specimen
1 mL platelet-poor plasma collected in 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-Sat; Report available: Next day
Reference Range
> 6 months: 23-32 seconds
Pediatric < or = 6 months: Not established
Pediatric < or = 6 months: Not established
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.
