Thromb Haemost 1993; 70(06): 0925-0931
DOI: 10.1055/s-0038-1649701
Original Article
Clinical Studies
Schattauer GmbH Stuttgart

The Textarin/Ecarin Ratio: A Confirmatory Test for Lupus Anticoagulants

Douglas A Triplett
The Department of Research, Ball Memorial Hospital, Muncie, Indiana, USA, and Pentapharm AG, Basel, Switzerland
,
Kurt F Stocker
The Department of Research, Ball Memorial Hospital, Muncie, Indiana, USA, and Pentapharm AG, Basel, Switzerland
,
Gail A Unger
The Department of Research, Ball Memorial Hospital, Muncie, Indiana, USA, and Pentapharm AG, Basel, Switzerland
,
Linda K Barna
The Department of Research, Ball Memorial Hospital, Muncie, Indiana, USA, and Pentapharm AG, Basel, Switzerland
› Author Affiliations
Further Information

Publication History

Received 14 May 1993

Accepted after revision 11 August 1993

Publication Date:
06 July 2018 (online)

Summary

Lupus anticoagulants (LA) are immunoglobulins (IgG, IgM, IgA or a mixture) which interfere with in vitro phospholipid (PL) dependent tests of coagulation (e.g. APTT, KCT, dilute Russell Viper Venom Time). LA are heterogeneous; consequently, the laboratory diagnosis is difficult and relies on multiple tests. We have developed a sensitive and relatively specific confirmatory test system based on fractions of two snake venoms. Textarin®, a protein fraction of Pseudonaja textilis venom (Australian Eastern brown snake), activates prothrombin in the presence of PL, factor V and calcium ions. Ecarin, a protein fraction of Echis carinatus venom, will activate prothrombin in the absence of any cofactors. The activation of prothrombin by Textarin yields thrombin while Ecarin yields meizothrombin. In the presence of LA, the Textarin time is prolonged and the Ecarin time is unaffected. The test results are reported as a ratio of Textarin/Ecarin times (abnormal greater than 1.3). We have evaluated this test system in the following patient populations: LA positive, therapeutically heparinized, stable oral anticoagulated, liver disease, routine preoperative, anticardiolipin antibody positive LA negative, hemophilia A, various other hereditary factor deficiencies or dysfunctional proteins, and specific inhibitors of factor V and factor VTII. The LA positive patients represented a mixed population of autoimmune disease, drug-induced and post-infectious states. Our findings indicate the sensitivity of the Textarin/Ecarin system in the confirmation of LA. In order to use the test system most effectively, it is recommended to incorporate poly-brene with Textarin when evaluating heparinized samples. Factor V deficiency and specific inhibitors of factor V yielded, in some instances, false positive results.