Conceptions and misconceptions in testing for lupus anticoagulants.

The aim of the following presentation is to review certain technical issues complicating clotting tests for lupus anticoagulants (LA). This is a field riddled with incorrect and misleading studies which often make progress difficult and which are difficult to retract. Inconsistent test sensitivity comparisons are sometimes due to incorrect methods being used but are more often due to contamination with platelets and instrument effects. Time dependence of LA is often due to pH drift during incubation and probably all LA are immediate acting (at least in our hands). The use of platelets in confirmatory tests is dangerous and can lead to false-positive results in patients with anti-factor V and heparin-like inhibitors.