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Test Code LAB320 Prothrombin Time

Department

HEMATOLOGY

Collection Requirements

For patients NOT on any anticoagulant medication. Order Therapeutic Prothrombin Time (TPT) if patient is on anticoagulant medication.

Must be a full draw.

Mix thoroughly immediately after collection.

Primary Collection Container

Blue 2.7 mL (Citrate)

Transport

Ambient: 24 hours

Refrigerated: unacceptable

Frozen: 1 week, platelet-poor plasma

Preferred Transport Temperature

Ambient

Processing

Mix tube thoroughly before centrifugation. If freezing, prepare using the following method: Centrifuge specimen. Use a plastic pipette to transfer top three-quarters of plasma into labeled plastic tube. When removing the plasma layer, be careful not to disturb the cell layers. Plasma separated from cells goes back into the centrifuge for a second spin. After the second spin, use a pipette again to transfer plasma to a new set of labeled aliquot tubes, then freeze. Preparation of Platelet-Poor Plasma

Stability

Ambient: 24 hours

Refrigerated: Unacceptable

Frozen: Unacceptable

Processed:

Ambient: 24 hours

Refrigerated: Unacceptable

Frozen: 1 week

Minimum Testing Volume

2.7 mL

Reference Range

0-6 months:
PT - 8.0-16.6 seconds
PT Critical Values: >25.0
INR - 0.7-1.4
INR Critcal Value: >1.4

6 months - 120 years:
PT:10.1-14.4 seconds
PT Critical Value: >/=120.0
INR - 0.9-1.2
INR Critical Value: >/=1.8

Methodology

Turbidimetric Clot Detection

ACL Top

Performed

Sunday – Saturday

Reported

As completed

CPT Codes

85610

Unacceptable Conditions

Hemolyzed, clotted, short draw, refrigerated and serum specimens. Frozen whole blood.