Mixing Studies, PT

Mixing Studies, PT

Alternate Test Name

PT Mixing Studies

Epic Mnemonic
Sunquest Mnemonic

LAB321
PTMX

Category

Sendouts

Methodology

Prothrombin based clot assay

Test Performance Schedule

Monday-Thursday

Result Availability

Usual TAT 1-4 days.

Container

3Light 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
• Centrifuge the capped sodium citrate tube specimen tube for 15 minutes at 1500g(rcf). When removing plasma leave a minimum ¼ inch of plasma sitting on cells. The cellular layer contains the platelets which were separated from the plasma during centrifugation. Leave this cellular layer undisturbed. Pipette plasma in aliquot transport tubes for testing.
• Freeze PPP sample immediately (-20° C).

Transportation Instructions

Ambient (up to 1 hour in whole blood state)

Frozen (plasma only >1 hour)

Stability

Ambient:Up to 1 hour in whole blood state.

Frozen:Platelet poor plasma aliquoted and frozen within 1 hour of collection.

After separation from cells:

• 1 hour (15-25°C)

• 2 months (-20°C)

• 2 months (-70°C)

Causes for Rejection

• Collection tube not filled to the minimum fill line.
• Contaminated with heparin.
• Contains clots.
• Received more than 4 hours after collection and not frozen.

CPT Codes

85611

Effective/Revised

06/23/22

Used to investigate a prolonged prothrombin time, factor deficiency or factor inhibitor.