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Test Code PT Prothrombin Time with International Normalized Ratio (INR), Plasma

Specimen Requirements

Specimen must arrive within 4 hours of draw.

 

Draw a full, light blue-top (sodium citrate) tube. When drawing specimen, allow tube to fill completely. Invert gently several times to mix blood. Do not uncap tube once specimen has been drawn. Forward promptly at ambient temperature only.

Note:  Specimen will be rejected if clots are present in specimen tube.

Performing Laboratory

Conway Regional Clinical Laboratory Services

Reference Values

PROTHROMBIN

9.0-11.0 seconds - patient not on anticoagulant

INR

Suggested therapeutic INR ranges: 

2.0-3.0 - routine oral anticoagulant therapy

2.5-3.5 - oral anticoagulant therapy for patients receiving standard doses of Coumadin® for thromboembolic events and patients with mechanical heart valves

Critical value (automatic call-back):  >5.0

Methodology

Photo-Optical Detection

Day(s) Test Set Up

Monday through Sunday

Available STAT

Test Classification and CPT Coding

85610