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Partial Thromboplastin Time, Activated
Test Code763
CPT Codes
85730
Preferred Specimen
1 mL frozen platelet-poor plasma collected in a 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.3 mL
Other Acceptable Specimens
Whole blood collected in: 3.2% sodium citrate (light blue-top) tube
Proper blood to anticoagulant ratio is required
Proper blood to anticoagulant ratio is required
Instructions
Platelet Poor Plasma: Centrifuge light blue-top tube 15 minutes at approx. 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.
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.
Transport Temperature
Frozen
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
Room temperature: 24 hours
Refrigerated: Unacceptable
Frozen: Unacceptable
Separated platelet-poor plasma
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 14 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Grossly lipemic • 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: 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.
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.
