LUPUS INHIBITOR - plasma

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Specimen: 4.5 mL blood added to 0.5 mL citrate. Conventional coagulation specimen may not be suitable, since the sample has to be first depleted of platelets before testing. Indicate this test clearly on the request form so that it can be processed differently by the laboratory.

Method: Kaolin clotting time, PT using dilute thromboplastin, dilute Russell viper venom time, platelet neutralisation procedure.

Application: Investigation of prolonged APTT not corrected by normal plasma; SLE; unexplained recurrent fetal loss, vascular thrombosis.

Interpretation: Lupus inhibitor reported in 5-10% of patients with SLE, also in others without clinical or serological evidence of SLE. Associated with a tendency to vascular thrombosis, tendency to recurrent abortion. Bleeding does not occur, unless there is associated thrombocytopenia, or specific coagulation factor inhibitor. See also CARDIOLIPIN ANTIBODIES .

Reference: Exner T et al. Br J Haematol 1987; 17: 143-151. Triplett DA and Brandt J. Br J Haematol 1989; 73: 139-142. Harris EN. Br J Haematol 1990; 74: 1-10.

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