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Test Code PTTP Prothrombin Time, Plasma

Reporting Name

Prothrombin Time, P

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Screening assay to detect deficiencies of one or more coagulation factors (factors I, II, V, VII, X)

 

Screening assay to detect coagulation inhibition

 

Monitoring intensity of oral anticoagulant therapy when combined with INR reporting

Method Name

Coagulometric (Turbidimetric)


Specimen Required


Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. For complete instructions see Coagulation Guidelines for Specimen Handling and Processing

2. Centrifuge, remove plasma, and centrifuge plasma again.

3. Aliquot plasma into plastic vial leaving 0.25 mL in the bottom of centrifuged vial.

Additional Information: Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.


Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen (preferred) 30 days
  Ambient  24 hours

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Reference Values

PROTHROMBIN TIME:

9.4-12.5 seconds

 

INTERNATIONAL NORMALIZED RATIO (INR):

0.9-1.1

 

Standard intensity warfarin therapeutic range: 2.0-3.0

High intensity warfarin therapeutic range: 2.5-3.5

Interpretation

Prothrombin time (PT) may be prolonged due to deficiencies of factors X, VII, V, and II of the extrinsic pathway, presence of inhibitors, or oral anticoagulation therapy.

 

INR therapeutic ranges for orally administered drugs:

-Standard-intensity warfarin therapeutic range: 2.0 to 3.0

-High-intensity warfarin therapeutic range: 2.5 to 3.5

Note: The INR should only be used for patients on stable oral anticoagulant therapy, though it is reported for all patients despite whether they are receiving oral anticoagulants.

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 day

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

85610

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PTTP Prothrombin Time, P 34528-0

 

Result ID Test Result Name Result LOINC Value
PTTTP Prothrombin Time, P 5902-2
INRTP INR 6301-6