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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 # |
Lupus Anticoagulant
Test CodeLUPUS
Alias/See Also
Lupus Screen/ LA
CPT Codes
85613 85730
Preferred Specimen
(2) 4.5 ml of whole blood preferred (tube must be filled to the line)
Minimum Volume
2.7 ml of whole blood preferred (tube must be filled to the line)
Instructions
Collect full sodium citrate tube(s) (blue top). Send to lab immediately. If the specimen needs to be transported, centrifuge the specimen, aliquot the specimen into a separate container, centrifuge again, aliquot the specimen into 3 containers and freeze. If the Lupus is positive, sample will be referred for cardiolipin & antiphospholipid ab testing. APTT and TT included in panel.
Transport Container
Sodium Citrate (blue top)
Transport Temperature
Frozen
Specimen Stability
Specimen must be centrifuged within one hour of collection.
Room Temperature: Not acceptable
Refrigerated: 4 hours (centrifuged)
Frozen: 30 days
Room Temperature: Not acceptable
Refrigerated: 4 hours (centrifuged)
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Specimens which are not properly filled do not contain the proper anti-coagulant to blood ratio and are therefore rejected. Hemolyzed and clotted specimens are also unacceptable for testing.
Methodology
Clotting dRVVT
Setup Schedule
Testing performed on Monday and Thursday
Report Available
1-4 days
Reference Range
dRVVT screen to confirm ratio: <1.49 = No evidence of Lupus Anticoagulant.
1.49-1.60 = Equivocal.
>1.60 = Positive for Lupus Anticoagulant.
1.49-1.60 = Equivocal.
>1.60 = Positive for Lupus Anticoagulant.
Clinical Significance
Lupus anticoagulants (LAs) are autoantibodies directed against phospholipid-bound proteins such as beta-2glycoprotein 1, prothrombin, and thrombomodulin. LAs (along with cardiolipin antibodies) are antiphospholipid antibodies, a group of autoantibodies associated with unexplained thrombosis, recurrent fetal loss, and thrombocytopenia. Although LAs can occur in patients with SLE, they are more frequently detected in individuals with no evidence of an underlying immune disorder.
Because it is an antiphospholipid antibody, the LA causes prolongation of phospholipid-dependent clotting assays, such as the aPTT. The Lupus Anticoagulant test uses dilute Russell’s Viper Venom screening (LA1) and confirmatory (LA2) reagents. LA1 reagent initiates clotting by directly activating factor X. LA1 is highly sensitive to LAs; if present, they will prolong the LA1 screening clotting time. LA2 reagent contains a high phospholipid concentration; the excess phospholipid neutralizes the LA and “corrects” the clotting time.
The two test results are compared by calculating a ratio between them:
Screen clotting time
Ratio = Confirm clotting time
Because it is an antiphospholipid antibody, the LA causes prolongation of phospholipid-dependent clotting assays, such as the aPTT. The Lupus Anticoagulant test uses dilute Russell’s Viper Venom screening (LA1) and confirmatory (LA2) reagents. LA1 reagent initiates clotting by directly activating factor X. LA1 is highly sensitive to LAs; if present, they will prolong the LA1 screening clotting time. LA2 reagent contains a high phospholipid concentration; the excess phospholipid neutralizes the LA and “corrects” the clotting time.
The two test results are compared by calculating a ratio between them:
Screen clotting time
Ratio = Confirm clotting time
