List All Test Names Beginning With:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Microbiology Sources | Microbiology Tests | Anatomic Pathology | Cytopathology

Prothrombin Time/INR

Source Blood
Mnemonic PT
Specimen Requirements

Adult:
1 x 2.7 mL blue top sodium citrate plastic tube is preferred. 4.5 mL blue top sodium citrate glass tube is also acceptable.

Pediatric:
1 x 2.7 or 1.8 mL short-draw blue top sodium citrate tube

Whole blood. VENOUS COLLECTION ONLY. Skin puncture (capillary) collection is not acceptable.

It is important to fill tube to maximum draw.
Mix well by inverting. Indicate collection time on tube.

When using a winged blood collection set (butterfly needle) a discard tube must be used to remove the air in the tubing,if only a citrate tube is drawn or is the first tube drawn.

Specimen Handling DO NOT centrifuge. Keep at room temperature.
MUST be tested within 24 hours of collection.
Additional Information Prothrombin Time is reported in INR (International Normalized Ratio)
Testing Location Hematology-All Sites
Rural: CRHL
Testing Frequency Daily
Alternate Name(s) PT, INR
Reference Interval

INR: 0.9 - 1.1                  Click here for critical values.

INR Therapeutic Ranges:

 Condition  INR
 Prevention of Deep Vein Thrombosis  2.0 - 3.0 
 Prevention Recurrent Thrombosis  2.0 - 3.0 
 Cardiac Valve Replacement:
        Tissue Valve
         Mechanical Valve 		  
 2.0 - 3.0
 2.5 - 3.5
 Recurrent Systemic Embolism  2.5-3.5