Co-existent Acquired Haemophilia and Lupus Anticoagulant. A Thorny Issue.

Abstract

We read with interest the case of a 69 year old lady who presented clinically with bleeding and ecchimoses [1]. Investigations revealed a prolonged activated partial thromboplastin time (aPTT) at 110.2 s that corrected by 54 % with normal plasma though we are not told to what extent a dilute Russel viper venom time (DRVVT) was prolonged and corrected with hexagonal phospholipids. A factor VIII level was at 04 % (do the authors mean 0.4 or 4.0 %?) and anti-factor VIII level (Bethesda assay) of 08 % (do the authors mean 0.8 or 8.0 %?) with Table 1 showing a complex inhibitor behaviour. The authors have not quoted the thromboplastin used for their aPTT: (1) a lupus insensitive reagent would have been helpful; (2) factor sensitivity to different thromboplastins modulates the correction of the mixing study. In the presence of auto anti-factor VIII antibodies the Bethesda assay may present with a type II inhibitor pattern but LA may interfere with this assay [2]. In the scenario given by the authors a chromogenic FVIII should have been done as well as a FVIII inhibitor measured by immune assay though LA could still interfere with the latter. Likewise, the measurement of anticardiolipin or antibeta-2-glycoprotein-1 antibodies may have better supported the presence of a LA the evidence for which relies on an undisclosed DRVVT [2]. However, a FVIII concentration below 0.15 IU/mL may influence the DRVVT result according to the sensitivity of reagents. While the good clinical response to recombinant factor VII and immune suppression are in keeping with and acquired factor VIII inhibitor, the laboratory diagnosis of factor VIII is poorly supported and that of LA largely inadequate. LA tests based on direct prothrombin activation such as the Textarin/Ecarin [3] or the Taipan/Ecarin ratios [4] are more useful in the presence of factor VIII inhibitor, though not officially incorporated in the LA guidelines [5].