Kaolin Clotting Time

The kaolin clotting time (KCT) is a sensitive test used in the laboratory detection of lupus anticoagulants (LA) (Derksen and de Groot, Thromb Res 114:521–526, 2004). It is essentially an activated partial thromboplastin time (APTT) test with no added phospholipid. Kaolin acts as the activator in the KCT. In the absence of additional phospholipid reagent, the quality of the test sample is extremely important since the generation of thrombin completely depends on the presence of residual cell membranes and plasma lipids (Derksen and de Groot, Thromb Res 114:521–526, 2004). Since the test contains no exogenous phospholipid, a confirmatory test using excess phospholipid is required to confirm the presence of lupus anticoagulant in the sample (Court, Br J Biomed Sci 54:287–298, 1997).