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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
Partial Thromboplastin Time - Lupus Anticoagulant (PTTLA)
Test Code: PTTLA
Synonyms/Keywords
PTT-LA, Lupus Anticoagulant PTT,  APTT-LA, StaClot LA​
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
*Platelet Poor Plasma 3.2% Citrated Blue Top Tube (BTT)​ 0.75 mL ​ 0.75 mL ​ 0.5 mL​
Collection Processing Instructions
One 0.75 mL citrated Blue Top Tube (BTT) plasma aliquot.
If more than one coagulation test is ordered, a separate aliquot is needed for each test.  
-Collect in Citrated Blue Top Tube (BTT)
-Citrate anticoagulant must be adjusted for HCT >55%
-Tube must be at least 90% full
-Invert completely 3-4 times (without shaking) to mix
*See Instructions for: Preparation of Platelet Poor Plasma ​
Specimen Stability Information
Specimen Type Temperature Time
​Plasma ​Frozen ​6 months
Rejection Criteria
Clotted or Hemolyzed
​Contamination with IV or Hickman Line fluids
​Specimens that thaw during storage or transport
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Marshfield ​Monday, Wednesday, Friday ​Less than 2 hours ​Optical clot detection/Siemens BCSXP
Test Information
​To increase the sensitivity and specificity of the laboratory diagnosis of lupus anticoagulants (LA), both the DRVVT and the PTT-LA should be ordered. These two tests have been combined as a Lupus Anticoagulant Panel (LAPAN) test order.
 
Lupus anticoagulant testing (DRVVT and PTT-LA) should not be performed on patients receiving rivaroxaban, apixaban, dabigatran, edoxaban, or warfarin.  For patients on these medications, one may consider anticardiolipin antibody and/or anti-beta-2 glycoprotein 1 antibody testing.
Reference Range Information
Performing Location Reference Range
​Marshfield

PTTLA: 41.4 - 60.0 seconds

PTTLA < 60.0 seconds Negative for LA.

If PTTLA is greater than 60.0 seconds, a PTTHP is also performed and the difference of PTTLA-PTTHP is reported.

Difference: -1.4-10.8 seconds

Difference <=10.8: Negative for LA

Difference >10.8: Positive for LA​

Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​85732 Optical Clot Detection  ​
Synonyms/Keywords
PTT-LA, Lupus Anticoagulant PTT,  APTT-LA, StaClot LA​
Ordering Applications
Ordering Application Description
​Centricity ​PTT-LA
​Cerner ​Lupus Anticoagulant (PTT-LA)
​COM ​PTT-Lupus Anticoagulant
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
*Platelet Poor Plasma 3.2% Citrated Blue Top Tube (BTT)​ 0.75 mL ​ 0.75 mL ​ 0.5 mL​
Collection Processing Instructions
One 0.75 mL citrated Blue Top Tube (BTT) plasma aliquot.
If more than one coagulation test is ordered, a separate aliquot is needed for each test.  
-Collect in Citrated Blue Top Tube (BTT)
-Citrate anticoagulant must be adjusted for HCT >55%
-Tube must be at least 90% full
-Invert completely 3-4 times (without shaking) to mix
*See Instructions for: Preparation of Platelet Poor Plasma ​
Specimen Stability Information
Specimen Type Temperature Time
​Plasma ​Frozen ​6 months
Rejection Criteria
Clotted or Hemolyzed
​Contamination with IV or Hickman Line fluids
​Specimens that thaw during storage or transport
Test Information
​To increase the sensitivity and specificity of the laboratory diagnosis of lupus anticoagulants (LA), both the DRVVT and the PTT-LA should be ordered. These two tests have been combined as a Lupus Anticoagulant Panel (LAPAN) test order.
 
Lupus anticoagulant testing (DRVVT and PTT-LA) should not be performed on patients receiving rivaroxaban, apixaban, dabigatran, edoxaban, or warfarin.  For patients on these medications, one may consider anticardiolipin antibody and/or anti-beta-2 glycoprotein 1 antibody testing.
Reference Range Information
Performing Location Reference Range
​Marshfield

PTTLA: 41.4 - 60.0 seconds

PTTLA < 60.0 seconds Negative for LA.

If PTTLA is greater than 60.0 seconds, a PTTHP is also performed and the difference of PTTLA-PTTHP is reported.

Difference: -1.4-10.8 seconds

Difference <=10.8: Negative for LA

Difference >10.8: Positive for LA​

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Marshfield ​Monday, Wednesday, Friday ​Less than 2 hours ​Optical clot detection/Siemens BCSXP
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​85732 Optical Clot Detection  ​
For most current information refer to the Marshfield Laboratory online reference manual.