Sign in →

Test Code KPT PROTHROMBIN TIME INR

Important Note

Citrate Tube Guide

Methodology

Fibrin Formation Using Mechanical Clot Detection

Useful for monitoring intensity of oral anticoagulant therapy (Coumadin or warfarin) when combined with international normalized ratio (INR) reporting. It is also useful for screening for hemostatic disorders of the extrinsic pathway (factors II, V, VII, X, and fibrinogen), hepatic disease, or vitamin K deficiency.

Specimen Requirements

Specimen must arrive, be centrifuged, and tested within 24 hours of draw.

 

Specimen Type: Plasma

Container/Tube: Light-blue top (3.2% buffered sodium citrate, with yellow-striped label)

Specimen Volume: Full tube

Collection Instructions:

1. Tube must be filled to capacity.

2. Ratio of blood to anticoagulant is critical for valid coagulation results (9:1).

3. Send whole blood in original tube.

Additional Information: Hemolyzed specimen is not acceptable.

 

Citrate Tube Guide

Day(s) Test Set Up

Monday through Sunday

Reference Values

PT

    12.0 -14.9 seconds

INR

     2.0-3.5

Critical value (automatic call-back):

 

       ≤ 18 Years            Protime   > 30.0 seconds

                                      INR          > 4.0

       > 18 Years             INR          ≥ 5.0

 

 

Note: The INR was developed to standardize reporting of the PT assay test results for patients on oral anticoagulant therapy. This was necessary because variability in responsiveness of the different instrument and thromboplastin reagent combinations available resulted in dosing differences.

Performing Laboratory

Logan Health Medical Center Laboratory

Test Classification and CPT Coding

85610

Specimen Transport Temperature

Ambient 24 hours-Whole blood