New ISTH guidelines for lupus anticoagulant detection

AntiPhospholipid Syndrome (APS) is an autoimmune condition with clinical manifestations that include

• arterial and venous thrombosis,
• one or several unexplained foetal deaths,
• neurological problems,
• thrombocytopenia.

The diagnosis of APS is difficult and relies on the association of clinical symptoms with the laboratory detection of antiphospholipid antibodies (APA) and Lupus Anticoagulants (LA).

According to the international consensus, laboratory testing for LA should be limited to patients previously identified as having a significant probability of APS and must be in accordance with the following recommendations.

Two clot-based screening assays with different principles have to be used for LA screening:

• The dilute Russell’s viper venom time (dRVVT) is the first test considered for LA detection.
• The second test is an APTT reagent containing low phospholipids contentration and silica as activator.

On the other hand, the tests such as kaolin clotting time, dilute thromboplastin time (dTT) assay and the tests based on ecarin or textarin use are not recommended.

If the previous assays suspect a presence of LA, confirm tests should be carried out with reagents containing high phospholipid concentration.

Inhibitors and factor deficiencies have to be ruled out in mixing studies.

If the initial testing is positive, it is imperative to repeat it at least 12 weeks after.

Stago offers a large range of reagents for LA detection, and in accordance with the international guidelines.