Laboratory Identification of Lupus Anticoagulant (LA) Using Different Activated Partial Thromboplastin Time (APTT) Assays.

Introduction: The International Society of Thrombosis and Hemostasis (ISTH) guidelines suggest a three-step evaluation for the detection of lupus anticoagulant (LA), including screening, mixing, and confirmation. According to the guidelines, the LA assay based on activated partial thromboplastin time (APTT) should include an initial screening step followed by a confirmatory step that uses a higher concentration of phospholipids in either bilayer or hexagonal form. For the activator, the guidelines recommend using silica, though ellagic acid is also an option.