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# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Prothrombin Time - INR
Test Code: PT
Synonyms/Keywords
Protime, PT, INR​, i-Stat PT/INR, CSPT, CS PT, Code Stroke PT, Code Stroke Protime
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
No​ ​ Whole Blood, Plasma​ 3.2% Citrated Blue Top Tube (BTT)​ 1.0 mL Plasma​ 0.6 mL Plasma​
​i-Stat only = Whole Blood Fingerstick ​Sterile (no additive) non-anticoagulated clear top tube ​45 uL ​45 uL
Collection Processing Instructions
-Citrated Blue Top Tube (BTT) must be drawn to the fill line.
-Completely invert tube three or four times to mix. Do Not Shake.
-Centrifuge tube at 3000 rpm for 10 minutes or Stat Spin for 3 minutes at 8500 rpm with the brake OFF as soon as possible after collection.
-Perform testing within 24 hours of specimen collection or transfer plasma to polypropylene tube with plastic pipette for storage within two hours of collection.
 
If sending to another testing location: When APTT and Protime-INR are ordered together send only one frozen, plasma aliquot (1mL) for both tests, labeled with the APTT and Protime-INR specimen labels.  Separate Citrated Blue Top Tube (BTT) or room temperature plasma is not needed
 
i-Stat:  Samples must be tested immediately after collection.
Specimen Stability Information
Specimen Type Temperature Time
Whole Blood​ or Plasma Ambient​ 24 Hours​
Plasma​ Frozen (-18°C)​ 2 Weeks​
Frozen (-70°C)​ 6 Months​
Frozen thawed​ 19 Hours​
​i-Stat Whole Blood Fingerstick ​Ambient ​Must be tested immediately
Rejection Criteria
Specimens filled below the fill line
Clotted​
Frozen whole blood​
Known IV fluid or Hickman line fluid contamination ​
Specimens with abnormal results that have a Hct >55% that have not had the citrate anticoagulant adjusted​
​Specimens stored on ice or refrigerated (2-8 deg Celsius)
​i-Stat testing:  serum or plasma
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
*Bloomer​ ​Monday through Friday ​​Less than 2 hours ​Amperometrically/i-Stat*
*​Cadott​ ​Monday through Friday ​​Less than 2 hours ​Amperometrically/i-Stat*
*​Chetek​ ​​Monday through Friday ​Less than 2 hours​ ​Amperometrically/i-Stat*
Chippewa Falls Monday through Friday Less than 2 hours​ Optical Clot Detection/Sysmex CA-620
Colby/Abbotsford​ ​​Monday through Friday ​Less than 2 hours​ ​​​​Optical Clot Detection/Sysmex CA-620
​*Cornell ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​*Cumberland ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Diagnostic Treatment Center
​Monday through Sunday​ ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CS-2500​
*Eagle River​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​Eau Claire ​Monday through Sunday​ ​Less than 2 hours​ Optical Clot Detection/Sysmex CS-2500​
Flambeau Hospital
​Monday through Sunday​ ​Less than 2 hours​ Optical Clot Detection/Sysmex CS-2500​
*Hayward​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​Ladysmith ​Monday through Friday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-620
*Lake Hallie​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Lakeview Medical Center ​Monday through Sunday​ ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CS-2500​
*Lakewoods​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Marshfield​ ​Monday through Sunday​ ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CS-2500​
*​Menomonie​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
*​Mercer​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​Merrill ​Monday through Saturday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-660
​Minocqua ​Monday through Sunday​ ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CS-2500​
Mosinee​ ​Monday through Friday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-620

*Oakwood​

​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​Phillips ​Monday through Friday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-620
​Rhinelander ​Monday through Friday ​Less than 2 hours ​Optical Clot Detection/Sysmex CA-620
*​Stettin​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Stevens Point​ ​Monday through Friday ​Less than 2 hours​ Optical Clot Detection/Sysmex CA-660
​Wausau ​Monday through Sunday​ ​Less than 2 hours​ Optical Clot Detection/Sysmex CS-2500​
​Wisconsin Rapids ​Monday through Friday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-660
*​Wittenberg​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Test Information

​*I-stat testing is FDA approved for patients receiving Warfarin therapy only.  Patients not receiving anti-coagulation therapy or therapies that include other anti-coagulants require testing at another location; analytic time may be up to 1 day.

Hemolysis does not interfere with sample analysis, however it may be an indicator of clotting factor activation prior to testing.  Clinical correlation with results recommended.

Reference Range Information
Performing Location Reference Range
All Performing Sites 0.9-1.1 (INR)​
See Critical value List for list of current critical values
Interpretation

​Recommended therapeutic ranges for oral anticoagulant therapy:
Prophylaxis; venous thromboemb./high risk surgery: INR = 2.0-3.0.
Prophylaxis; venous thromboemb. hip surgery: INR = 2.0-3.0.
Treatment of deep vein thrombosis or pulmonary embolism: INR = 2.0-3.0.
To prevent systemic emboli with atrial fib., valvular heart disease, tissue heart valves or AMI: INR = 2.0-3.0. 
For mechanical prosthetic heart valves, recurrent systemic embolism: INR = 2.0-3.5.
Refer to Care Management-Anticoagulation Services.

Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
85610​
Synonyms/Keywords
Protime, PT, INR​, i-Stat PT/INR, CSPT, CS PT, Code Stroke PT, Code Stroke Protime
Ordering Applications
Ordering Application Description
​Centricity ​Prothrombin Time INR (PT)
​Cerner ​PT
​COM ​Prothrombin Time-INR
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
No​ ​ Whole Blood, Plasma​ 3.2% Citrated Blue Top Tube (BTT)​ 1.0 mL Plasma​ 0.6 mL Plasma​
​i-Stat only = Whole Blood Fingerstick ​Sterile (no additive) non-anticoagulated clear top tube ​45 uL ​45 uL
Collection Processing Instructions
-Citrated Blue Top Tube (BTT) must be drawn to the fill line.
-Completely invert tube three or four times to mix. Do Not Shake.
-Centrifuge tube at 3000 rpm for 10 minutes or Stat Spin for 3 minutes at 8500 rpm with the brake OFF as soon as possible after collection.
-Perform testing within 24 hours of specimen collection or transfer plasma to polypropylene tube with plastic pipette for storage within two hours of collection.
 
If sending to another testing location: When APTT and Protime-INR are ordered together send only one frozen, plasma aliquot (1mL) for both tests, labeled with the APTT and Protime-INR specimen labels.  Separate Citrated Blue Top Tube (BTT) or room temperature plasma is not needed
 
i-Stat:  Samples must be tested immediately after collection.
Specimen Stability Information
Specimen Type Temperature Time
Whole Blood​ or Plasma Ambient​ 24 Hours​
Plasma​ Frozen (-18°C)​ 2 Weeks​
Frozen (-70°C)​ 6 Months​
Frozen thawed​ 19 Hours​
​i-Stat Whole Blood Fingerstick ​Ambient ​Must be tested immediately
Rejection Criteria
Specimens filled below the fill line
Clotted​
Frozen whole blood​
Known IV fluid or Hickman line fluid contamination ​
Specimens with abnormal results that have a Hct >55% that have not had the citrate anticoagulant adjusted​
​Specimens stored on ice or refrigerated (2-8 deg Celsius)
​i-Stat testing:  serum or plasma
Test Information

​*I-stat testing is FDA approved for patients receiving Warfarin therapy only.  Patients not receiving anti-coagulation therapy or therapies that include other anti-coagulants require testing at another location; analytic time may be up to 1 day.

Hemolysis does not interfere with sample analysis, however it may be an indicator of clotting factor activation prior to testing.  Clinical correlation with results recommended.

Reference Range Information
Performing Location Reference Range
All Performing Sites 0.9-1.1 (INR)​
See Critical value List for list of current critical values
Interpretation

​Recommended therapeutic ranges for oral anticoagulant therapy:
Prophylaxis; venous thromboemb./high risk surgery: INR = 2.0-3.0.
Prophylaxis; venous thromboemb. hip surgery: INR = 2.0-3.0.
Treatment of deep vein thrombosis or pulmonary embolism: INR = 2.0-3.0.
To prevent systemic emboli with atrial fib., valvular heart disease, tissue heart valves or AMI: INR = 2.0-3.0. 
For mechanical prosthetic heart valves, recurrent systemic embolism: INR = 2.0-3.5.
Refer to Care Management-Anticoagulation Services.

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
*Bloomer​ ​Monday through Friday ​​Less than 2 hours ​Amperometrically/i-Stat*
*​Cadott​ ​Monday through Friday ​​Less than 2 hours ​Amperometrically/i-Stat*
*​Chetek​ ​​Monday through Friday ​Less than 2 hours​ ​Amperometrically/i-Stat*
Chippewa Falls Monday through Friday Less than 2 hours​ Optical Clot Detection/Sysmex CA-620
Colby/Abbotsford​ ​​Monday through Friday ​Less than 2 hours​ ​​​​Optical Clot Detection/Sysmex CA-620
​*Cornell ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​*Cumberland ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Diagnostic Treatment Center
​Monday through Sunday​ ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CS-2500​
*Eagle River​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​Eau Claire ​Monday through Sunday​ ​Less than 2 hours​ Optical Clot Detection/Sysmex CS-2500​
Flambeau Hospital
​Monday through Sunday​ ​Less than 2 hours​ Optical Clot Detection/Sysmex CS-2500​
*Hayward​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​Ladysmith ​Monday through Friday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-620
*Lake Hallie​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Lakeview Medical Center ​Monday through Sunday​ ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CS-2500​
*Lakewoods​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Marshfield​ ​Monday through Sunday​ ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CS-2500​
*​Menomonie​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
*​Mercer​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​Merrill ​Monday through Saturday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-660
​Minocqua ​Monday through Sunday​ ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CS-2500​
Mosinee​ ​Monday through Friday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-620

*Oakwood​

​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
​Phillips ​Monday through Friday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-620
​Rhinelander ​Monday through Friday ​Less than 2 hours ​Optical Clot Detection/Sysmex CA-620
*​Stettin​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
Stevens Point​ ​Monday through Friday ​Less than 2 hours​ Optical Clot Detection/Sysmex CA-660
​Wausau ​Monday through Sunday​ ​Less than 2 hours​ Optical Clot Detection/Sysmex CS-2500​
​Wisconsin Rapids ​Monday through Friday ​Less than 2 hours​ ​Optical Clot Detection/Sysmex CA-660
*​Wittenberg​ ​​Monday through Friday ​Less than 2 hours​ ​​Amperometrically/i-Stat*
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
85610​
For most current information refer to the Marshfield Laboratory online reference manual.