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Test Code PTINR Prothrombin Time (INR)

Additional Codes

EPIC LAB4255

Synonyms

  • INR
  • Protime
  • PT

Purpose

Prothrombin (PT) is used for evaluation of Factors X, VII, V, and II (extrinsic pathway) and to monitor oral anticoagulant therapy.

Methodology

Chromogenic analysis

Sample Type

Preferred Sample Type
Light blue top - Na Citrate Plasma

Centrifuge: Yes

Specimen Minimum Volume

0.5 mL

 

NOTE: Na Citrate Blue top tubes require that the tube is filled adequately to maintain the 9:1 blood to anticoagulant ratio.

Specimen Stability

Temperature Time
Ambient (18-25°C) (store) 8 hours
Refrigerated (2-8°C) N/A
Frozen (-20°C) 14 days
Frozen (<-70°C) 6 months

NOTE: Separate plasma from cells within 2 hours

Reference Ranges

Normal Range
PT 9.4 - 12.5 sec
INR 0.80 - 1.10

 

Therapeutic Range
INR 2.00 - 3.00

 

Critical Value
INR >4.49

 

Technical Range
PT 8.0 - 320.0 sec
INR 0.07 - 28.30

 

Rejection Criteria

  • Clotted samples
  • Underfilled or overfilled samples

Availability

Performed STAT
24/7 Yes

 

Performing Laboratory

MultiCare Yakima Memorial Hospital Laboratory

Lab Department

Hematology

CPT Code

85610

LOINC

34528-0 PT panel Coag (PPP)