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Test Code LAB320 Protime (PT), Blood

Important Note

Please see the Coagulation Limitations under resources for effect of Anticoagulant drugs in this test.

Reporting Title

Protime

Methodology

Diagnostica Stago Inc. STA®-Neoplastine CL Plus

Used as a screening test for coagulation abnormalities including extrinsic coagulation factors, and for monitoring oral anticoagulant therapy.

Performing Laboratory

OhioHealth Laboratory Services-RMH, GMC, DNH, DMH, MGH, GMH, HMH, GCMH, DHC, WECC, PMH, MH, SH, BH and OBH Core Laboratories.

Specimen Requirements

Whole blood unspun specimen must arrive within 48 hours of draw.

Draw a full, light blue-top (citrate) tube; and send citrated whole blood. Invert several times to mix blood. Do not refrigerate.

Note:  Gross hemolysis, icterus, and lipemia may also affect results.

 

Outpatients/Outreach Clients (when testing is not able to be performed on whole blood within 48 hours, send frozen plasma)

Plasma-Frozen

Draw a full, light blue-top (citrate) tube. Spin down, remove plasma, spin plasma again, and place 1 mL of citrated platelet-poor plasma into a plastic vial. (Glass vial is not acceptable.) Pour-off vial should be no more than 2/3 full. Send specimen frozen.

 

Specimen Stability Information

Specimen Type Temperature Time
Unspun whole blood Room Temperature 48 hours
Spun, capped whole blood Room temperature 8 hours
     
     
Frozen plasma stable  

 

Specimen Transport Temperature

Ambient OK

Refrigerate NO

Frozen OK

Reference Values

PT

11.8-14.3  seconds

INTERNATIONAL NORMALIZED RATIO (INR)

0.8-1.1

During the induction phase of oral anticoagulation, the INR may not reflect the anticoagulation status of the patient.

THERAPEUTIC RANGES FOR INR

Most clinical situations:  2.0-3.0

Mechanical prosthetic valve:  2.5-3.5

Critical value: >5.0

Alerting category: Always called within 1 hour

Note:  PT results may be affected by a number of commonly administered drugs. These should be considered when unusual or unexpected results are obtained. Unexpected abnormal results should be followed by further coagulation studies to determine the source of the abnormality.

Day(s) Test Set Up

Monday through Sunday; Continuously

Test Classification and CPT Coding

85610