Lupus anticoagulant assays: questions answered and to be answered.

CONTEXT

Lupus anticoagulants are antibodies with heterogenous specificities to phospholipids. They have been associated with clinical syndromes consisting of thrombosis and recurrent fetal loss.

OBJECTIVE

To address questions about the laboratory assay aspects of lupus anticoagulants. This review is intended for clinicians managing lupus anticoagulant testing in clinical laboratories.

DATA SOURCES

Published literature on lupus anticoagulants, with emphasis on laboratory assay methods.

CONCLUSIONS

Although there are published criteria for confirming the presence of a lupus anticoagulant, there is no consensus on assay methods for lupus anticoagulant testing. The mixing study is a useful screening test for lupus anticoagulants, but it may have limited utility. Clinical context may necessitate the performance of factor assays in addition to lupus anticoagulant testing to rule out factor deficiency or factor-specific inhibitor. Additionally, the presence of different anticoagulants may affect the reliability of lupus anticoagulant assays. Lupus anticoagulants are an independent risk factor for thrombosis. It may be useful to use different assays when there is clinical suspicion for a lupus anticoagulant. When testing for lupus anticoagulants, clinicians must carefully consider the clinical context because factor assays may also be indicated.