LA

a.k.a. Lupus anticoagulant is an immunoglobulin that binds to phospholipids and interferes with the coagulation process in vitro leading to a prolonged PTT. Although the PTT is elevated in LA, the name is a misnomer because it is not an anticoagulant but rather causing thrombosis in vivo. Also most patients with LA do not have Lupus (SLE) . When presented with a prolonged PTT, a mixing study is performed. If the PTT is corrected, then LA is excluded. However, if the clotting time is still prolonged, then the presence of an inhibitor is confirmed, which includes LA. Confirmation of LA is then confirmed through a phospholipid sensitive test such as Dilute Russell’s Viper Venom Time (see dRVVT).