LUPUS ANTICOAGULANT- LA
Pre-test preparation or requirements
• Sample can be drawn at any time. No fasting or special preparation required.
• Sample taken in Citrated vial should be immediately centrifuged and transfer plasma to aliquot.
LA screen/ LA confirm test ratio:
Negative: < 1.3
Weak Positive: 1.3-1.5
Moderate Positive: 1.5-1.8
High Positive: 1.8-2.4
Strong Positive: >2.4
Significance of test
Lupus anticoagulants (LA) are auto antibodies that prolong phospholipid base clotting protein based constitutients of cells and plasma. They are an integral part of the APLA syndrome and can be associated with conditions such as SLE and other connective tissue disorders, HIV and other infection and malignancies. LA could also be drug and transient.
The results of two separate and independent screening tests for LA, name dilute APTT and RVVT need to be confirmed by neutralization assays using an excess of phospholipids, positive result need to be confirmed 12 weeks later to rule out transient LA. The patient result is to be interpreted in the contest of clinical sittings. The patient should not be on oral anticoagulant theraphy or heparin at the time of testing.
Lupus Anti Coagulants (LAC) are associated with numerous clinical states: Lupus, Thrombocytopenia, recurrent spontaneous abortions idiopathic thromboembolic disease.
Other causes of false positivity.
Presence of heparin
Intrinsic pathway factor deficiency
Presence of factor inhibitors