aPTT 1:1 Mix (incubated)

Profile or Test Panel
Abnormal PT or aPTT Reflexive Evaluation Profile
Additional assays will be performed as indicated.
Intrinsic Factor Evaluation Profile
Extrinsic Factor (abnormal PT) Evaluation Profile
Bleeding Diathesis with a Normal aPTT/PT Profile
DIC Panel
Factor VIII Inhibitor Profile
Factor Inhibitor non-Factor VIII Profile
Fibrinolysis Evaluation Profile
Lupus Anticoagulant Profile
Abnormal result reflexes to the following tests as indicated.
von Willebrand Profile
If the aPTT is prolonged and the factor VIII is normal, this panel reflexes to an aPTT Reflexive Evaluation Profile.
Also Known as (Alias) PTT
Indications Patient with prolonged aPTT and suspected acquired factor inhibitor, particularly acquired FVIII inhibitor.
Method Clottable
Test Information Reflexive test if the aPTT 1:1 mix test is abnormal and etiology unknown.
Additional Test Information If a specific inhibitor is suspected, then  a 1:1 mix (patient plasma : normal plasma) is incubated at 37°C for 60 minutes.  Then an aPTT is repeated.  Normal ranges are included on testing report and can be made available upon request.
Sample Requirements Whole Blood:  3.2% sodium citrated (blue top)  OR
frozen plasma.
Requested Volume Two 5 ml 3.2% sodium citrated (blue top) tubes as whole blood  OR frozen plasma in 4 X 1mL aliquots in plastic tubes.
Minimum Volume or Pediatric Volume Frozen Plasma:  at least 0.5ml in 2 plastic tubes.
Sample Information Whole blood is preferred for testing, but if it is not possible to send whole blood tubes TO ARRIVE HERE WITHIN 2 HOURS of collection, then send frozen plasma:  Centrifuge blue top tubes at 1500g for 15 minutes and remove the plasma and centrifuge a second time at 1500g for an additional 15 minutes.  Aliquot approximately 1 ml of plasma into 4 plastic tubes, and freeze.
Shipping Information Whole Blood:  Send at ambient temperature (18-25°C) and must be received within the lab in less than or equal to 2 hours after collection.

Frozen Plasma:  Send on dry ice

Send samples to:
Bloodworks Northwest
Attn: Hemostasis Laboratory
921 Terry Ave
Seattle, WA 98104

For additional information, please see Ordering Information

Requisition Form RFT- Hemostasis Reference Laboratory
Transaction Code 3200-10
CPT Codes 85732
Test Schedule Monday – Friday
Turn around Time (analytic time) 3 Business Day
Report/Results Fax number required to receive report

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