Sign in →

Test Code PTI Prothrombin Time

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Light Blue Top Tube, 3.2% Sodium Citrate

Other Acceptable specimens: N/A

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

NOTE: Once each blue top tube is completely filled, gently invert the sample tube at least five times to ensure complete mixing of the contents.

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Collect specimen per standard collection procedure.
  • Once each blue top tube is completely filled, gently invert the sample tube at least five times to ensure complete mixing of the contents.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Carefully remove plasma from cells using a plastic transfer pipette avoiding buffy coat.
  • Aliquot removed plasma into 2 plastic tubes containing a minimum of 0.5 mL of specimen in each tube.
  • Plasma samples must then be frozen at -20oC.
  • Once solidly frozen, they must be shipped on dry ice. Samples that have thawed in transit will be rejected.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that have wrong ratio of blood to anticoagulant (fill volume), clotted or grossly hemolyzed.

Reference Values

 

Test

Age

Sex

Reference Range

PT

All

All

12.6 - 15.0 seconds

INR

All

All

0.9 - 1.1

Critical Values

Analyte

Unit

Low

High

Age

INR

N/A

N/A

>3.9

All

CPT Codes

85610 

LOINC Codes

5902-2, 6301-6

Volume

Preferred Volume: 1.0 mL

 

Minimum Volume: 0.5 mL

Specimen Stability

Storage Temperature

Stability

Room temperature

24 hours

Refrigerated

not acceptable

Frozen

30 days

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

NOTE: Once each blue top tube is completely filled, gently invert the sample tube at least five times to ensure complete mixing of the contents.

 

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

STAT Turnaround Time: 40 minutes

 

Routine Turnaround Time: 4 hours

 

Testing Schedule: 24/7

Clinical Indications

Screening to identify a deficiency of one or more clotting factors of the extrinsic and common coagulation pathways.

 

Monitoring patients on oral anticoagulant therapy

Test Components

Prothrombin Time (PT)
International Normalized Ratio (INR)

 

Methodology

Clotting

Synonyms/Keyword Search

INR; PT; Prothrombin Time

Additional Information

3.2% sodium citrate light blue top tubes must have 9 to 1 ratio of blood to anticoagulant

Last Review Date

02/28/2024