Mixing Studies (PT/APTT)

For Specimen Integrity during Extreme Weather see the “Lockbox Usage in Extreme Weather” document at the top of this page.

If unable to process and properly store specimens within 4 hours of collection then call CompuNet transportation for a STAT pick-up at (937) 297-8262 option 1.

This test needs a completed Anticoagulant Drug List submitted with the specimen. For a copy of the 2 page form click here

Samples must be received in the Special Coagulation department at the Sandridge location by 3:00pm for same day results.

MIXSTY

70360;
Correction Studies

PT
APTT
Thrombin Clotting Time (TCT)
Reflexes:
PT 1:1 mix (reflexes to this if PT is prolonged)
APTT 1:1 mix (reflexes to this if APTT is prolonged)
APTT 1:4 mix (reflexes to this if APTT is prolonged)

2 plastic (2.7mL) completely filled 3.2% Sodium Citrate (light blue top) tubes

2 Frozen Capped aliquots of Sodium Citrate plasma (Polypropylene tubes recommended)

Use standard venipuncture and disposal techniques.
Collect the required quantity of Sodium Citrate (light blue top) tubes.
If unable to process specimens within 4 hours of collection then call CompuNet transportation for a STAT pick-up at (937) 297-8262 option 1.

Sodium Citrate (light blue top) tube(s): Process immediately (stable only 4 hours), following instructions below:
Note: We recommend aliquot tubes to be made of polypropylene plastic as this material is safe to freeze at <-70 degrees C.
1. Centrifuge capped Sodium Citrate (light blue top) tubes at 3000 rpm for 10 minutes, or at speed and time required to consistently produce Platelet Poor Plasma (<5/kmm3).
2. Carefully remove the plasma from all Sodium Citrate (light blue top) tubes; avoid disturbing the WBC/buffy coat, and combine all plasma into a plastic conical centrifuge tube.
Note: If the plasma shows any hemolysis, it must be recollected.
3. Centrifuge the plasma in the plastic conical centrifuge tube for a second time as in step 1.
4. In one smooth motion, carefully and quickly pour the centrifuged plasma into a second plastic conical centrifuge tube. A small amount of plasma along with a red cell button should remain on the bottom of the original conical tube if the pour was executed correctly.
Note: This quick-pour method prevents platelet transfer and contamination.
5. Aliquot at least 1mL of plasma into each aliquot tubes labeled “plasma.” Refer to the Minimum Volume section above for the number of aliquots required per test.
6. Finally, place all aliquots into a <-20°C freezer within 4 hours.
Note: Aliquots must remain frozen until they are picked up by the CompuNet courier. Call CompuNet transportation department if frozen specimen boxes are needed.

Whole blood Sodium Citrate (light blue top) tubes
    OR
Frozen -Capped aliquots of Sodium Citrate plasma (Polypropylene tubes recommended)

Room Temperature: Whole blood Sodium Citrate (light blue top) tubes
Refrigerated: Unacceptable for Sodium Citrate (light blue top) tubes whole blood or capped plasma aliquots
Frozen: Capped aliquots of Sodium Citrate plasma (

Room Temperature: Whole blood Sodium Citrate (light blue top) tubes < 4 hours
Refrigerated: Unacceptable for Sodium Citrate (light blue top) tubes whole blood or capped plasma aliquots
Frozen: Capped aliquots of Sodium Citrate plasma (polypropylene tubes recommended) at <-20oC for < 15days
                                                                                                                                              at <-70oC for <6 months

Rejected for hemolysis, clotted, improper fill, incorrect specimen type, thawed frozen aliquots, refrigerated plasma or blood, expired test tubes, >4 hours old if not processed into separated frozen plasma vials.

Monday - Friday
SCOAG

Same day if received by 3:00pm
One day when received after 3:00pm

Anti-Coagulant medications

The Mixing Studies test is one step in the investigation of prolonged PT’s and APTT’s. Based on these results, more specific tests can be run, such as factor-specific inhibitor titers (Bethesda assays) and non-specific inhibitors (Lupus Anticoagulant assays).