Mixing Studies, APTT

Mixing Studies, APTT

Alternate Test Name

PTT Mixing Studies

Epic Mnemonic
Sunquest Mnemonic

LAB326
APTTMX

Category

Sendouts

Methodology

Activated partial thromboplastin clot based assay

Test Performance Schedule

Monday - Friday

Result Availability

1 – 4 days

Container

3 Light blue top (3.2% buffered sodium citrate) tubes

Volume

Pref. Vol.: 8.1 mL (4 - 6 aliquots, minimum of 0.5 ml each)
Min. Vol.: 5.4 mL (4 - 6 aliquots, minimum of 0.5 ml each)

Collection Instructions

• Routine venipuncture
• Immediately after collection, gently invert tube 5 -10 times
• Specimen must be processed within 1 hour of collection
• Platelet-poor plasma: Centrifuge light-blue top for 15 minutes at approximately 1500 g within 1 hour 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).
• Separate plasma into 4-6 aliquots, minimum of 0.5 mL each
• Freeze immediately

Transportation Instructions

Frozen

Stability

• Room Temperature: Unacceptable
• Refrigerated: Unacceptable
• Frozen: 2 months (Platelet poor plasma, aliquoted and frozen within 1 hour of collection)

Causes for Rejection

• Citrate tube underfilled
• Clotted or hemolyzed specimens
• Platelet-poor plasma not frozen with 1 hour of collection

CPT Codes

85732

Effective/Revised

4/16/21