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Test Code WARF PT Warfarin Prothrombin Time + INR

Clinical System Name

Warfarin Prothrombin Time + INR
 

Synonyms

INR
Protime
PT
PT INR

Description

The Warfarin PT test is used to monitor patients receiving Warfarin therapy.

Sample Requirements

 

Specimen: Whole Blood

Container(s): Lt Blue/Citrate

Preferred Vol: 1.8 mL

Minimum Vol: N

 

Note:  Preferred method of collection is venipuncture with vacuum fill.  Test results are affected by incorrect blood volume.  Use of a Vascular Access Device for the  collection of coag testing is not recommended.

If this method is used it requires a 5 cc clearing volume; 3 cc for size 2 French catheter or smaller. Blood must be trasferred to the  Lt Blue/Citrate tube by use of a  blood transfer device to ensure proper fill. 

Specimen should be centrifuged within 1 hour of collection.

 

Processing Instructions

Reject due to: Clotted, Hemolyzed, Insufficient quantity, and  Improper collection.

Spin:N

Aliquot:N

Temp:RT

Storage location: Core 6 ( -70 C)  Freezer.

 

Note: Deliver blood to Core Coag bench.  Coag Technologist will process. Specimen should be centrifuged within 1 hour of collection. Spin whole blood, remove plasma. Transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label.

 

 

 

Off-site collection: Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volumel. Use of a Vascular Access Device for the collection of coag testing is not recommended. If this method is used it requires a 5 cc clearing volume; 3 cc for size 2 French catheter or smaller. Blood must be trasferred to the Lt Blue/Citrate tube by use of the blood transfer device.

Specimen should be centrifuged within 1 hour of collection. Double spin, transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label. Freeze 2 aliquots of 1.0 mL plasma in plastic tubes at -70C.

Ship frozen on dry ice.

Stability

Specimen Type Temperature Time
Citrated platelet-poor plasma Room temp N
  Refrigerated N
  Frozen   -20 C or -70 C 3 m

 

Availability

STAT Performed TAT
Y

Daily

1 h

 

Performing Laboratory

Seattle Children's Laboratory    

 

Department

Department:  Coagulation

Phone Number: 206 987-2578

 

 

 

Reference Range

Reference range determined by provider.

 

Methodology

Method:  Electromagnetic mechanical clot detection system by STA® - Compact Analyzer

Analytical Volume: 1 mL plasma

This is enough for a PT, PTT, TT, and Fibrinogen on the same sample.

 

Limitations: Method is affected by improper collection, processing and storage.

High hematocrit greater than or equal to 56% requires a citrate adjusted tube.

CPT Codes

85610

Critical Values

 

Critical INR
Less than or equal to 1.5 or greater than or equal to 4.0