Lupus anticoagulants: pathogenesis and laboratory diagnosis

The pathogenesis of the lupus anticoagulant (LA) has been the focus of much research over the past decade, and a plethora of laboratory tests have been developed to detect it. This essay reviews the nature of LA and its pathogenesis, and a number of approaches employed in its diagnosis. These range from well established tests such as the kaolin clotting time (KCT), activated partial thromboplastin time (APTT) and tissue thromboplastin inhibition test (TTI), to the 'newer' tests such as the dilute Russell's viper venom time (DRVVT) and more recent snake venom tests such as the textarin/ecarin ratio and Taipan snake venom time (TSVT). The criteria for diagnosis are discussed, including pre-analytical variables such as sample preparation, and the effects of therapeutic anticoagulants used to treat thrombotic manifestations of the syndrome or an underlying disease process.