Lupus Anticoagulant Testing: Activated Partial Thromboplastin Time (APTT) and Silica Clotting Time (SCT).

Actvated partial thromboplastin time and its congener test Silica clotting time are used for the laboratory detection of lupus anticoagulants. Their performance consists of mixing test plasma with activators of the contact coagulation factors, phospholipids and calcium chloride, and recording the clotting time. Here we describe the principle, performance and extensive practical details of the two methods, the problems that may be encountered and how they can be identified and overcome.