No single screening test can detect all LA-positive patients. Several tests are available, and at least two should be employed to verify the presence of LA. Before any LA screening test is done, a thrombin time (TT) should be performed to rule out therapeutic heparin or the presence of a thrombin (factor II) inhibitor.
These are some of the LA screening procedures that can then be used:
- Dilute Russell's Viper Venom Time (DRVVT): This test utilizes a reagent containing venom from the viper Vipera russelli (which activates factor X), low levels of phospholipids, and calcium ions in a clotting time test. The DRVVT test principle is based on the idea that the reagents can help to identify the antibody's dependence on phospholipids.
- Platelet neutralization procedure: This assay will show the dependence on phospholipids for the lupus anticoagulant to take effect. This can be performed using the aPTT-based technique with the DRVVT test or using Taipan snake venom time tests.
- Kaolin clotting time or silica clotting time
- Hexagonal Phospholipid test (HPP): This is a similar assay to the platelet neutralization procedure but thought to be more sensitive.
