Technoclot® LA (Lupus Anticoagulant) Screen is a simplified (one-stage) dilute Russell’s Viper Venom (dRVV) test. It is comprised of a simplified, complete system for the detection of Lupus Anticoagulant.
Technoclot® LA Screen and Technoclot® LA Confirm contain Russell’s viper venom, phospholipids anti heparin agents, calcium, buffers, stabilizers, sodium azide and dyes.
Russell’s viper venom present in LA Screen initiate plasma clotting by directly activating factor X. LA antibodies prolong the LA Screen clotting time.
Technoclot® LA Confirm is similar to Technoclot® LA Screen but contains a high phospholipid concentration. The extra phospholipid counteracts the LA antibody and largely corrects the clot time.
DRVV tests “bypass” factor VII of the extrinsic pathway and the contact and antihemophilic factors of the intrinsic pathway. Therefore Technoclot® LA Screen is more specific for LA than aPTTs as they are not affected by contact factor abnormalities or by factor FVIII deficiencies or antibodies. They have been a number of tests developed based on phospholipid correction however none have been as convenient to use as LA Confirm subsequent to LA Screen.
Mixing tests may be useful to exclude factor II, V and X deficiencies, which may prolong LA Screen and LA Confirm results. Mixing normal plasma with test plasma replenishes any factors deficient in the test plasma. If the mixing test is still prolonged, it indicates that an inhibitor (such as LA) is present in the test plasma.