The positive rate of lupus anticoagulant according to the each understanding disease in our hospital

We investigated positive rate of lupus anticoagulant (LA) according to the each understanding disease in our hospital. 596 cases (F/M 477/149, 7-87 y.o.) were examined from 2003 to 2004 years. LA tests were performed using 2 methods such as kaolin clotting time (KCT) mixing test and dilute Russell's viper venom time (dRVVT). The LA tests were most frequently ordered in dermatology, and the most common purpose of LA test was the check of existence of antiphospholipid (aPL) in patients with collagen diseases. The LA positive rate was the highest in patients with SLE among the collagen diseases, and in patients with cerebral infarction among the thrombotic diseases. The LA positive rate exceeded 40% in ITP and livedo reticularis. Moreover, LA positive rate was 16% in preoperative tests of the orthopedic patients without any physical diseases. Thus, it was suggested that there were considerable numbers of the asymptomatic LA positive persons. The LA positive cases based on KCT only accounted for about 60% of all the LA positive cases. Among the thrombotic patients, there were not the DVT/PE patients with only KCT positive. On the other hands, the KCT positive rate was higher than the dRVVT positive rate in patients with cerebral infarction. There were not dRVVT single positive cases in patients with recurrent abortion and ITP, but KCT single positive case accounted for about 90%. From these results, it is suggested that there is a difference in KCT and dRVVT about detecting aPL, and that care should be taken to interpret the LA test.