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Prothrombin Time (PT/INR)

Justification

The Prothrombin Time (PT) is a general coagulation screening test for congenital and acquired deficiencies of the extrinsic coagulation pathway factors (X, VII, V, II, and I). It is also useful in monitoring coumadin anticoagulation. An International Normalized Ratio (INR) is calculated that allows for monitoring of warfarin anticoagulation, accounting for differences in PT reagents and allowing results across different laboratories to be compared.

STAT: < 24 hours (7 days a week)

Clot-based

Draw Tube: Blue Top

Sample Type: Citrated Plasma

Specimen Requirements

Sample Type Volume Required Minimum Volume Stability
PREFERRED Citrated Plasma 1mL 0.5mL Frozen (-20C): 2 weeks
Frozen (-80C): 6 months
ALTERNATIVE - - - -
REJECTION CRITERIA Thawed in transit, refrozen or clotted sample
SPECIAL INSTRUCTIONS -

General Information

METHODOLOGY Clot-based
STAT TAT < 24 hours (7 days a week)
STAT TAT Performance > 90% of results released in 24 hours 7 days a week
ROUTINE TAT < 24 hours (M-F)
ALTERNATIVE NAMES PT, International Normalized Ratio, INR
DESCRIPTION Coagulation screening assay using a high sensitivity thromboplastin reagent based on recombinant human tissue factor.
LIMITATIONS -
NORMAL RANGE 10.2-13.4 seconds
ASSOCIATED TESTING -
REFERENCES -
SAMPLE REPORT Upon request
NEW YORK STATE APPROVED -

Test Codes

ORDER CODE P3106
CPT CODE 85610
LOINC CODE 5902-2, 6301-6