Sign in →

Test Code PT 1:1 PT Mixing Study (PT 1:1 Mix)

Important Note

Draw 1 tube- Must be completely filled.

If transport to the lab will exceed 24 hours: Immediately centrifuge the specimen and aliquot 2 mL of plasma into a separate plastic vial.  Send specimen frozen.

Performing Laboratory

Memorial Hospital Laboratory- Automated Procedures      304-388-5953       

Specimen Requirements

Plasma- Light Blue Top, Sodium Citrate

Draw 1 full, tube by “clean” venipuncture (no excessive trauma).

Immediately after draw, invert tubes several times to mix blood with additive.

Specimen Rejection

  • Improperly labeled, collected, stored, and transported
  • Quantity not sufficient
  • Hemolyzed 
  • Lipemic
  • Clotted
  • When the mixing study is ordered, if the result of the undiluted PT is within 5 seconds of the upper limit of normal, the mixing study will be cancelled.

Storage and Stability

Unspun Room temperature 18-24oC 24 hours
Spun Room temperature 18-24oC 4 hours
Frozen < -20oC 2 weeks

Reference Values

Prothrombin time ranges may vary depending on specific lot number of reagent used in the laboratory.

 

Critical Value: INR > 4.49

 

Interpretation

Mixing studies are performed to help determine if the patient has a factor deficiency or a possible inhibitor.  Determination of the inhibitor may require incubation of the mixture at variable time intervals.

Methodology

Clot detection

Days Test Set Up and Turnaround

Monday through Sunday, Continuously

AM Collection Expected by 9AM same day
Routine Expected within 24 hrs
Stat Expected within 1 hr
Timed Expected results are test dependant

CPT Coding

85611