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Order Code LAB2652 Prothrombin Time (PT) with International Normalized Ratio (INR), Blood

Additional Codes

Test Name in EPIC

EPIC Test Code           

Mnemonic

RV PROTIME/INR

LAB2652

PT/INR

PRIOR TO 8/1/21:  PT

Useful For

PT/INR is useful for monitoring the coagulation status of patients on oral anticoagulation therapy such as coumadin/warfarin.

Specimen Requirements

Draw a full, light blue-top (sodium citrate) tube. For pediatric (minimum ) volume use the 1.8 mL tube.  Allow tube to fill completely. Invert gently several times to mix blood. Do not uncap tube.  If collected at a non-performing location, frozen platelet-poor plasma is preferred.        

 

Special Note: If PT/aPTT testing is to be performed on the same specimen, please adhere to aPTT platelet-poor plasma instructions, which require initial centrifugation within 4 hours of collection.        

Specimen Stability

Specimen Type Temperature Stability                    
Whole Blood Ambient 24 hours
Platelet Poor Plasma (See below) Frozen 2 weeks

Platelet Poor Plasma Instructions:

  1. Centrifuge the primary tube within 24 hours of draw
  2. Transfer plasma to an aliquot tube
  3. Centrifuge the aliquot tube
  4. Transfer plasma to a second aliquot tube
  5. Freeze the second aliquot tube

Rejection Criteria

  1. Specimens that are clotted
  2. Visible hemolysis
  3. Tube volume below minimum fill line (<90% expected fill) or above maximum fill line

Reference Values

Note:  These recommended values serve as guidelines.

  • PT:  9.4-12.5
  • INR:    0.9 - 1.1
  • PT/INR:  2.0 - 3.0 (prevention and treatment of deep vein thrombosis, chronic atrial fibrillation, prevention of systemic embolism in myocardial infarction, prosthetic tissue heart valves)
  • PT/INR:  2.5 - 3.5 (prosthetic mechanical heart valves)
  • Critical value (automatic call-back):  INR > 5.0

Day(s) Test Set Up

Monday through Sunday

Performing Laboratory

Ridgeview Medical Center Laboratory

Two Twelve Medical Center Laboratory

Ridgeview Sibley Medical Center Laboratory

Ridgeview Le Sueur Medical Center Laboratory

Methodology

Photo-Optical Clot Detection

Test Classification and CPT Coding

85610