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The reappraisal of dilute tissue thromboplastin inhibition test in the diagnosis of lupus anticoagulant
Author(s) -
Liu H. W.,
Wong K. L.,
Lin C. K.,
Wong W. S.,
Tse P. W. T.,
Chan G. T. C.
Publication year - 1989
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1989.tb07687.x
Subject(s) - thromboplastin , tissue factor , lupus anticoagulant , partial thromboplastin time , clotting time , medicine , factor x , clotting factor , immunology , coagulation , platelet , thrombin , thrombosis
Summary. The dilute tissue thromboplastin inhibition (DTTI) test (Schleider et al. 1976) is a sensitive but non‐specific test for lupus anticoagulant (LA). False positive results are seen in patients with clotting factor deficiency involving the extrinsic pathway and also in some patients with specific factor inhibitors (Triplett et al. 1983; Rosove et al. 1986). Since the effect of LA is phospholipid dependent but those of factor deficiency and specific inhibitors are not, we analyse the test results by comparing the degree of inhibition using different dilutions of tissue thromboplastin and express it as the DTTI index. This is defined as the clotting time ratio with 0·2% tissue thromboplastin divided by the clotting time ratio with 2% tissue thromboplastin. We also perform a dilute tissue thromboplastin time with platelet substitution to see if this could neutralize the inhibition caused by LA. Both of these modifications can reliably distinguish LA from other conditions associated with prolonged APTT better than the original DTTI test.