From Don Wahl, Sanford Health: What are the recommended tests to include in a lupus anticoagulant/antiphospholipid antibody (LA/APL) panel? Is there an antiphospholipid group that gives recommendations? Thank you, Don.
Hello, Don, and thank you for your question. The group you need is provided in the title of this reference, and the reference provides the assays that are currently recommended. :Pengo V, Tripodi A, Reber G, et al: Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibody of the Scientific and Standardisation Committee of the International Society on Thrombosis and haemostasis. Update of the guidelines for lupus anticoagulant detection. J Thromb Haemost 2009;7:1737-1740.
For LA, Pengo’s recommendations are:
Choose two assays based on different laboratory principles…
- Low-PL dilute Russell viper venom time (DRVVT) is the first test considered
- LA-sensitive low-phospholipid PTT with silica activator is the second test considered
- Presume LA is present if either of the two tests is prolonged beyond the upper limit of the reference interval
When the screen is prolonged, confirmatory tests are performed using bilayer or hex-phase high-PL reagents…
- Locally compute the mean percent corrections
- Establish the 99th percentile reference limit by testing LA-negative plasmas using low- and high-PL (screen/confirm) reagents
- Locally compute the individual percent corrections by using [(screen–confirm)/screen x 100]
If patient plasma % correction is ≥ 99th percentile correction, LA is confirmed.
To continue, in addition to LA, the enzyme immunoassays you should employ are the anti-cardiolipin antibody and the anti-beta-2-glycoprotein 1. Many use the assays specific for the IgG isotype in both cases.
For an overview of LA/APL testing, see our audio PowerPoint modules, Lupus Anticoagulant 1 and Lupus Anticoagulant 2. Also, with apologies for self-promotion, please watch for our article, McGlasson DL, Fritsma GA, Comparison of six dilute Russell viper venom time lupus anticoagulant screen/confirm assay kits. Semin Thromb Hemost2013, currently in preparation.